Study on Ecological Threshold of Groundwater in Typical Salinization Area of Qian’an County

A suitable groundwater level is an important condition to maintain the stability of the vegetation community, especially in arid and semi-arid areas. The surface of Qian’an County in Western Jilin Province is often accompanied by salinization due to the influence of natural and human factors. In order to maintain the healthy development of ecological vegetation and reduce the risk of soil salinization, the concept of an ecological threshold of groundwater level is proposed, and two methods are used to determine the reasonable ecological threshold of groundwater. (1) Based on field investigation and indoor experiment, the data layer of soil texture, land use type and groundwater mineralization degree in the research area was established by using remote sensing technology and GIS technology. According to the thickness of vegetation root layer and the height of capillary rise of different soil and water types, the influence of groundwater salinity is considered, and the sum of the two is taken as the ecological threshold of groundwater in the study area. The reasonable threshold value of suitable growth of various vegetation crops is 3.76~5.66 m. (2) According to the relationship between the normalized vegetation index (NDVI) and the groundwater buried depth and phreatic salt, the groundwater buried depth and the mineralization degree under the best vegetation cover are analyzed as follows: the buried depth of groundwater is between 4.8 m and 6.1 m, and the salinity of groundwater is between 0.37 and 1.25 g/L, which are reasonable groundwater properties in the study area of the ecological threshold. This result not only enriches and broadens the content of groundwater research, but also helps to predict the prospect of water resource development

Pd-Co₃[Co(CN)₆]₂ hybrid nanoparticles:Preparation, characterization, and challenge for the Suzuki-Miyaura coupling of aryl chlorides under mild conditions

A simple approach for the synthesis of a Pd–MOF nanocatalyst with high activity for Suzuki coupling of aryl chlorides was reported.</p

Hydrogeochemical Characteristics of Fluoride in the Groundwater of Shuangliao City, China

This study investigated the hydrogeochemical characteristics of fluoride in the groundwater of Shuangliao City. This paper analyzes the effects of different forms of hydrochemistry and the chemical speciation of fluorine in water. The results showed that an area of high fluorine was located in the northern section of Shuangliao City, and the soil salinization degree was also high in this area. The chemical composition of groundwater was mainly formed by the evaporation-concentration process; both pH (weak alkaline environment) and total dissolved solids (TDS) had a positive effect on fluorine enrichment within a certain range; Na+ and F- had significant positive correlation, HCO3- and F- had a weak positive correlation, and Ca2+ was the only ion with a negative correlation with F-

Risk Assessment of Groundwater Pollution in a Mining Area Based on Physical Processes

At present, the study of groundwater pollution risk assessment is generally based on the study of groundwater vulnerability. The impact of the pollutants themselves has not been paid more attention. The assessment of the risk of groundwater pollution should include two aspects: one is the contaminated nature of the aquifer itself and the other is spatial distribution of the pollutant. The vulnerability of the aquifer is only the natural susceptibility of the aquifer to the contaminant. Therefore, the risk assessment of groundwater pollution should also reflect the distribution and transport of pollutants in an aquifer. This study takes a tailings area as an example, and puts forward the risk assessment method of groundwater pollution based on physical processes. Before aquifer contamination occurs, the experts determine spatial distribution of each risk level according to the surrounding economic and social sensitivity conditions and hydrogeological conditions; and then use the numerical model to invert the intensity of the pollution source corresponding to each risk level. The results show that this method can express the distribution in space and time of risk level. For a single point source of contamination, this method is better than the previous based on aquifer vulnerability risk assessment method

MicroRNA-31 Function as a Suppressor Was Regulated by Epigenetic Mechanisms in Gastric Cancer

Gastric cancer is one of the most lethal malignancies worldwide. The aberrant expression of microRNA-31 (miR-31) has been reported in gastric cancer; however, its regulation mechanisms are still unclear. Here, we confirmed that miR-31 expression was significantly decreased in gastric cancer tissue and cell lines. Ectopic expression of miR-31 potentially suppresses proliferation and induced early apoptosis in gastric cancer cells. Furthermore, miR-31 expression was regulated as a result of epigenetic mechanisms. The downregulation of miR-31 was associated with promoter DNA methylation status in gastric cancer and cell lines. Moreover, we found that HDAC2 was the direct target of miR-31 by binding to 3′-UTR from the results of luciferase reporter assays, qRT-PCR, and western blotting. HDAC2 played an activation role in tumor growth, whose expression is upregulated and inversely associated with miR-31 levels. All the results suggested that miR-31 function as a crucial tumor suppressor was regulated by epigenetic mechanisms in gastric cancer. We found an epigenetic pathway loop, DNA methylation-miRNA expression-target gene-tumor progression in gastric cancer, and also provided implications for molecular diagnosis and therapeutics of gastric malignancies by detecting miR-31 as a potential target

Missing-linker-confined single-atomic Pt nanozymes for enzymatic theranostics of tumor

Conventional nanozymes often possess low active site density. Pursuing effective strategies for constructing highly active single-atomic nanosystems with maximum atom utilization efficiency is exceptionally attractive. Herein, we develop a facile "missing-linker-confined coordination" strategy to fabricate two self-assembled nanozymes, i.e., conventional nanozyme (NE) and single-atomic nanozyme (SAE), which respectively consist of Pt nanoparticles and single Pt atoms as active catalytic sites anchored in metal-organic frameworks (MOFs) with encapsulated photosensitizers for catalase-mimicking enhanced photodynamic therapy. Compared to a Pt nanoparticle-based conventional nanozyme, a Pt single-atomic nanozyme shows enhanced catalase-mimicking activity in generating oxygen for overcoming tumor hypoxia, thus exhibiting a more efficient reactive oxygen species generation and high tumor inhibition rate.National Research Foundation (NRF)Submitted/Accepted versionThe research is supported by the National Natural Science Foundation (22072140), the National Key R&D Program of China (2021YFA1600202), the Singapore National Research Foundation Investigatorship (NRF‐NRFI2018‐03), the Fundamental Research Funds for the Central Universities (YD9990002021), and Anhui Key Research and Development Program (201904a07020092)

Fishery Status and Rebuilding of Major Economic Fishes in the Largest Freshwater Lake in China Based on Limited Data

Poyang Lake, the largest freshwater lake in China, possesses abundant fishery resources, but its fish stock status is still unclear. In this work, the stock status of and fishing efforts of nine major economic fishes in the Poyang Lake were estimated from 2000 to 2019 with a catch-based maximum sustainable yield (CMSY) model based on catch and resilience data. It was further predicted whether the biomass of those fishes could be restored to support maximum sustainable yield (Bmsy) under the policy of “Ten years fishing moratorium in the Yangtze River”. The results showed that goldfish Carassius auratus, grass carp Ctenopharyngodon idella, and black carp Mylopharyngodon piceus suffered from higher fishing efforts and low biomass in the past 20 years; bighead carp Hypophthalmichthys nobilis, yellow catfish Tachysurus fulvidraco, and common carp Cyprinus carpio responded differently to their fishing efforts; silver carp Hypophthalmichthys molitrix, Amur catfish Silurus asotus, and mandarin fish Siniperca chuatsi were underexploited. Six species were overfished in 2019, and their biomass would be expected to recover for sustainable exploitation during the fishing moratorium, except for M. piceus. This study provided a case study of feasible freshwater fishery evaluation in limnetic ecosystems

Synergistic deficiency and heterojunction engineering boosted VO2 redox kinetics for aqueous zinc-ion batteries with superior comprehensive performance

© 2020 Elsevier B.V. Aqueous zinc-ion batteries (ZIBs) are promising for cost-efficient and safe energy storage but are still hindered by the limiting comprehensive performance of cathode materials. Deficiency and heterojunction engineering are both highly accredited strategies for boosting the intrinsic ion/electron kinetics and structural stability of these materials, however, neither of above-mentioned strategies could achieve a satisfied effect due to their own limitations. Obviously, the fine combination of the advantages of deficiency and heterojunction engineering should be an effective way towards further improvement. As a proof of concept, here, we take VO2 as an example to construct a spongy three-dimensional (3D) VO2 composite with enriched oxygen vacancies and graphene-modified heterointerfaces (Od-VO2-rG). The density functional theory (DFT) calculations confirm that oxygen vacancies could effectively modulate the Zn2+ adsorption energy resulting in reversible Zn2+ adsorption/desorption. Meanwhile, the graphene-modified heterointerface enables the rapid electron transfer. Impressively, Od-VO2-rG delivers superior comprehensive performance with high capacity (376 mAh g−1 at 0.1 A g−1), impressive rate capability (116 mAh g−1 at 20 A g−1) and satisfactory cycling stability (88.6% capacity retention after 5000 cycles). This rational design by combining deficiency and heterojunction engineering opens up a method towards advanced electrode materials for superior comprehensive performance