Evolution of physicochemical and leaching characteristics of municipal solid waste incineration fly ash in China under ultra-low emission standard.

The physical and chemical characteristics of fly ash has changed significantly under ultra-low emission system and the current leaching system is no longer suitable for high alkalinity fly ash. This work investigated the pH values and evolution of physical and chemical characteristics of fly ash from 24 typical municipal solid waste incineration plants in China. The pH value of the leaching solution obtained by HJ/T 300-2007 presented two different acid and alkali characteristics, where high and low alkalinity fly ash accounted for 54.17% and 45.83%, respectively. The alkali content in fly ash increased significantly after ultra-low emission standard, increasing by 18.24% compared with before the implementation of GB 18485-2014. The leaching behavior of high alkalinity fly ash showed the illusion that they could enter the landfill only by the addition of a small amount of chelating agent or even without stabilization treatment, and its long-term landfill risk is significant. The phase change of high alkalinity fly ash and pH value change of the leaching solution after carbonation were the key factors for the leaching concentration change of heavy metals. Therefore, it is recommended to improve the existing leaching system or conduct accelerated carbonization experiments to scientifically evaluate the long-term leaching characteristics of high alkalinity fly ash, and to reduce the risk of heavy metal release from high alkalinity FA after entering the landfill site.

Facile Synthesis of Porous g-C3N4 with Enhanced Visible-Light Photoactivity.

Porous graphitic carbon nitride (g-C3N4) was prepared by dicyandiamide and urea via the pyrolysis method, which possessed enhanced visible-light-driven photocatalytic performance. Its surface area was increased from 17.12 to 48.00 m2/g. The porous structure not only enhanced the light capture capacity, but also accelerated the mass transfer ability. The Di (Dicyandiamide)/Ur (Urea) composite possessed better photocatalytic activity for Rhodamine B in visible light than that of g-C3N4. Moreover, the Di/Ur-4:5 composite showed the best photoactivity, which was almost 5.8 times that of g-C3N4. The enhanced photocatalytic activity showed that holes and superoxide radical played a key role in the process of photodegradation, which was ascribed to the enhanced separation of photogenerated carriers. The efficient separation of photogenerated electron-hole pairs may be owing to the higher surface area, O dopant, and pore volumes, which can not only improve the trapping opportunities of charge carriers but also the retarded charge carrier recombination. Therefore, it is expected that the composite would be a promising candidate material for organic pollutant degradation.

Themes and ideologies in China's diplomatic discourse - a corpus-assisted discourse analysis in China's official speeches.

Diplomatic discourse is a formalized form of political communication that significantly influences a country's international perception. However, there is a research gap in the analysis of China's diplomatic discourse, particularly in relation to the speeches available on the official Chinese Foreign Ministry website. This study aims to address this gap by conducting a quantitative and qualitative analysis of China's diplomatic speeches. This study utilizes a quantitative corpus-assisted discourse analysis to explore the prevalent themes in China's official speeches. Additionally, qualitative discourse analysis is employed to examine the ideologies manifested in specific examples from the official speeches. The research combines a corpus-based approach with critical discourse analysis to investigate language use, discourse practices, and social practices. The analysis of China's diplomatic discourse reveals several key themes related to President Xi Jinping's leadership, international relations, and future community and economy. The findings provide valuable insights into China's diplomatic strategies and its international image, emphasizing its commitment to cooperation, development, and peace. This research contributes to a better understanding of China's diplomatic discourse and its role in shaping international perceptions of the country. By highlighting the prevalent themes and ideologies in China's official speeches, the study emphasizes China's commitment to fostering positive international relations. The findings offer valuable insights into China's diplomatic strategies and its efforts to shape its international image.

Spatiotemporal difference of leachate production and its impact on the development and dynamics of LCS clogging.

Due to the complexity of industrial solid waste, heavy metals and organics can be enriched in leachate. While leachate is difficult to handle, it can also cause clog of the leachate collection system (LCS), increasing the risk of leakage. Therefore, it is necessary to study the clogging process of LCS in industrial solid waste landfills (ISWLs). In this study, the prediction of the clogging process and hydraulic conductivity evolution of the LCS in ISWL were carried out through laboratory experiments and model simulations. The results show that the LCS of ISWLs in China faces severe clogging challenges. First, the rate of clogging is inversely proportional to the rate of leachate production. Then, it was found that the main influencing factor was infiltration conditions (precipitation and capping systems). Under accelerated infiltration conditions, the time for complete clogging of the leachate drainage pipes was shortened from the initial 26-735 years to 11-315 years. The time to complete LCS clogging was shortened from the initial 78-2205 years to 32-945 years. In addition, the acceleration of the clogging process was fully consistent with the increase in leachate production. In particular, when the net infiltration volume increases from 0 to 50 mm, the clogging process is significantly accelerated. After greater than 50 mm, the effect on the clogging process gradually decreases. This provides a reliable theoretical basis for accurately predicting the clogging process of LCS.

Research on leakage environmental risk assessment and risk prevention and control measures in the long-term landfill process of ultra-alkaline fly ash.

In this study, we simulated the actual landfill disposal process using accelerated carbonization experiments, based on the leaching characteristics of heavy metals from "alkaline" fly ash, and used the LandSim-HELP coupling model to assess the environmental risk of the leaching. The results showed that the leaching data of "alkaline" fly ash before carbonization showed the illusion of admission to landfill with only a small amount of chemical addition or even without curing/stabilization. The leached concentrations of Zn and Cd from "alkaline" fly ash after carbonation were significantly higher. The risk assessment of the leakage of heavy metals in the case of a single artificial composite liner system showed that the exposure concentrations of Pb, Zn, and Cd in samples exceeded Standard for groundwater quality (GB/T 14848-2017) the Class III permissible limits after carbonation; exposure risk for Cd was exceeded in all samples. However, although the use of a double-layer artificial composite liner to improve the level of impermeability effectively reduced the risk of Cd leaching, so that none of the non-carcinogenic risks exceeded the standard, the carcinogenic risk of Cd in the carbonized samples exceeded the factor of 1.1-4.5 of the acceptable hazard quotient, and the contamination characteristics of the alkaline fly ash still need to be kept in view.

LDI-MVFNet: A Multi-view fusion deep network for leachate distribution imaging.

The accurate monitoring and early warning of groundwater pollution caused by the concealed leakage of landfills is a major challenge globally in the field of solid waste management and groundwater protection. Electrical resistivity tomography (ERT) represents a potential solution with advantages, owing to its fast and nondestructive characteristics. However, traditional ERT based on a single array cannot reveal the distribution and dynamics of pollution in complex underground media owing to the limited information it carries. We designed a novel deep network for multi-view fusion to invert the real resistivity distribution of the medium caused by leachate (named LDI-MVFNet) so as to infer the distribution of leachate. To support model establishment and validation, ERT instances collected from synthetic models and a salt tracer experiment were inverted. We compared the inversion results of the LDI-MVFNet with those of single arrays and found that the LDI-MVFNet performed the best overall. The average root mean square error (RMSE) of synthetic models reached 0.98, performing better than Dipole-Dipole (3.86), Wenner-Schlumberger (3.37), and Pole-Pole (6.61), which were inverted separately. The resultant inverted subsurface true resistivity data were presented in the form of two-dimensional (2D) cross sections. The imaging results of 2D cross sections showed that LDI-MVFNet was superior to others in data noise suppression and inversion accuracy. The results of this study indicate that the data fusion of multiple views can more accurately reflect the real resistivity than the inversion of a single array can.

Dynamic evolution and response strategy of demand in buffer zone between scattered groundwater sources and hazardous waste landfill.

Groundwater contamination by landfill leachate is a major concern. Ignoring the long-term increase in leakage caused by the aging of engineered materials may lead to underestimation of the buffer distance (BFD) demand of landfills. In this study, a long-term BFD prediction model was developed by coupling an engineering material aging and defect evolution module with leachate leakage and migration transformation model, and was applicated and validated. The results showed that under landfill performance degradation, the required BFD was 2400 m, i.e., 6 times higher than under undegraded conditions. With the degradation of the performance, the BFD required to attenuate the heavy metal concentrations of groundwater increases more than the BFD required to attenuate organic pollutants. For example, the BFD required for zinc (Zn) was 5 times higher than that required for undegraded conditions, while for 2,4-dichlorophenol (2,4-D), the BFD was 1 times higher. Considering the uncertainties of the model parameters and structure, the BFD should be greater than 3000 m to ensure long-term safe water use under unfavorable conditions such as large leachate production and leakage, weak degradation and fast diffusion of pollutants. If the actual BFD does not meet the demand due to landfill performance degradation, the landfill owner can reduce the reliance on the BFD by reducing the waste leaching behavior. For example, the landfill in our case study would require a BFD of 2400 m, but by reducing the leaching concentration of zinc in the waste from 120 to 55 mg/L, this requirement could be reduced to 900 m.

The molecular mechanism of baicalein repressing progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway.

BACKGROUND: Baicalein (BAI) has a significant anti-cancerous function in the treatment of gastric cancer (GC). Focal adhesion kinase (FAK) is a key regulatory molecule in integrin and growth factor receptor mediated signaling. MicroRNA-7 (miR-7), has been considered as a potential tumor suppressor in a variety of cancers. However, the possible mechanisms by which BAI inhibiting progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway remain unclear. PURPOSE: To investigate the molecular mechanism and effects of BAI inhibiting progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway. METHODS: Gastric cancer cell lines with FAK knockdown and overexpression were constructed by lentivirus transfection. After BAI treatment, the effects of FAK protein on proliferation, metastasis and angiogenesis of gastric cancer cells were detected by MTT, EdU, colony formation, wound healing, transwell and Matrigel tube formation assays. In vivo experiment was performed by xenograft model. Immunofluorescence and western blot assay were used to detect the effects of FAK protein on the expression levels of EMT markers and PI3K/AKT signaling pathway related proteins. qRT-PCR and luciferase reporter assay were used to clarify the targeting relationship between miR-7 and FAK. RESULTS: BAI can regulate FAK to affect proliferation, metastasis and angiogenesis of gastric cancer cells through PI3K/AKT signaling pathway. qRT-PCR showed BAI can upregulated the expression of miR-7 and luciferase reporter assay showed the targeting relationship between miR-7 and FAK. Additionally, miR-7 mediates cell proliferation, metastasis and angiogenesis by directly targeting FAK 3'UTR to inhibit FAK expression. CONCLUSION: BAI repressing progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway.

High Removal Efficiency of Diatomite-Based X Zeolite for Cu2+ and Zn2.

Diatomite-based X zeolite was obtained and its crystallinity, morphology, and interface properties were investigated by XRD, BET, SEM, EDS, and XRF. The obtained X zeolite possessed a unique meso-microporous structure and showed good ion exchange properties for Cu2+ and Zn2+. The pseudo-second-order model and Langmuir isotherm model can best describe the adsorption kinetics and isotherms of Cu2+ and Zn2+, respectively. The maximal adsorption capacities of X zeolite for Cu2+ and Zn2+ were 146 and 195 mg/g at 323 K, respectively. Meanwhile, the adsorption process for Cu2+ and Zn2+ were chemical adsorption and ion exchange, respectively. Furthermore, the adsorption data turned out to be an endothermic and spontaneous process. Compared with other reported materials, the adsorption capacity of X zeolite synthesized from diatomite was among the highest. Therefore, it could be a promising adsorbent for the disposal of wastewater that contains metal ions.

A general framework and practical procedure for improving pxrf measurement accuracy with integrating moisture content and organic matter content parameters.

Rapid, accurate detection of heavy-metal content is extremely important for precise risk control and targeted remediation. Herein, a general modeling method and process based on the relationship between Pxrf measured values and site parameters are explored to construct a Pxrf correction model suitable to improve each site's measurement accuracy. Results show a significant correlation between Pb, Mn, and Zn Pxrf measured values and actual concentrations, with correlation coefficients between 0.8 and 0.93. Through the correlation analysis, the correlation coefficient between the water content and the measured value of pxrf is in the range of 0.2-0.5. Pxrf measurement of all heavy metals was weakly affected by soil organic matter content, with correlation coefficients all lower than 0.5. Model transformation effectively improved the correlation between measured Pxrf value and actual concentration, and transformation increased the correlations of Sr, Mn, and Cu by around 0.11. Model verification results showed that the Pb, Zn, Fe, and Mn models can be used to improve Pxrf method detection accuracy.

Antimicrobial activity of X zeolite exchanged with Cu2+ and Zn2+ on Escherichia coli and Staphylococcus aureus.

The biocidal cations of Cu2+ and Zn2+ were hosted on the surfaces and in the cavities of X zeolite via ion exchange. The microstructure and interface properties of the exchanged zeolite X samples were analyzed by XRD, SEM, XPS, and XRF. The as-prepared samples showed excellent antimicrobial activity towards gram-negative bacteria of Escherichia coli and gram-positive bacteria of Staphylococcus aureus. Furthermore, the batch antimicrobial experiments showed that the bacterial disinfection process fitted well with the first order model. The Cu2+-zeolite showed excellent and better antibacterial performance on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1 h with the initial Cu2+-zeolite concentrations of 1000 ppm and 100 ppm, respectively. However, the Zn2+-zeolites were found to be less effective on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1 h with the initial Zn2+-zeolite concentrations of 500 ppm and 1000 ppm, respectively. In addition, the relationships between the apparent rate constant (k) and reagent concentration (C) were also systematically investigated. The present results suggest that the as-prepared samples could be promising antibacterial materials for the efficient disinfection of contaminated water with bacteria.

One-Step Hydrothermal Synthesis of Zeolite X Powder from Natural Low-Grade Diatomite.

Zeolite X powder was synthesized using natural low-grade diatomite as the main source of Si but only as a partial source of Al via a simple and green hydrothermal method. The microstructure and surface properties of the obtained samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), wavelength dispersive X-ray fluorescence (XRF), calcium ion exchange capacity (CEC), thermogravimetric-differential thermal (TG-DTA) analysis, and N2 adsorption-desorption technique. The influence of various synthesis factors, including aging time and temperature, crystallization time and temperature, Na2O/SiO2 and H2O/Na2O ratio on the CEC of zeolite, were systematically investigated. The as-synthesized zeolite X with binary meso-microporous structure possessed remarkable thermal stability, high calcium ion exchange capacity of 248 mg/g and large surface area of 453 m²/g. In addition, the calcium ion exchange capacity of zeolite X was found to be mainly determined by the crystallization degree. In conclusion, the synthesized zeolite X using diatomite as a cost-effective raw material in this study has great potential for industrial application such as catalyst support and adsorbent.