Antibiotic resistance genes (ARGs) have become as emerging contaminant with great concerns worldwide due to their threats to human health. It is thus urgent to develop techniques to degrade ARGs in water. In this study, MoS2@Fe3O4 (MF) particles were fabricated and used to activate peroxymonosulfate (PMS) for the degradation of four types of free DNA bases (T, A, C, and G, major components of ARGs) and ARGs. We found that MF/PMS system could effectively degrade all four DNA bases (T within 10 min, A within 30 min, C within 5 min, and G within 5 min) in very short time. During the reaction process, MF could activate PMS to form the reactive radicals such as ·OH, SO4·−, O2·−, and 1O2, contributing to the degradation of DNA bases. Due to the low adsorption energy, high charge transfer, and great capability for PMS cleavage, MF exhibited excellent PMS adsorption and activation performances. MoS2 in MF could enhance the cycle of Fe(III)/Fe(II), improving the catalytic performance. Excellent catalytic performances of MF/PMS system were achieved in complex water matrix (including different solution pH, coexisting of anions and natural organic matter) as well as in real water samples (including tap water, river water, sea water, and sewage) especially under high salinity conditions due to the generation of Cl· radicals and HClO species. MF/PMS system could also efficiently degrade ARGs (chromosomal kanR and plasmid gmrA) and DNA extracted from antibiotic resistant bacteria (ARB) in super-short time. Moreover, complete disinfection of two types of model ARB (E. coli K-12 MG 1655 and E. coli S17–1) could also be achieved in MF/PMS system. The high degradation performances of MF/PMS system achieved in the reused experiments and the 14-day continuous flow reactor experiments indicated the stability of MF particles. Due to the magnetic property, it would be convenient to separate MF particles from water after use via using magnet, facilitating their reuse of MF and avoiding potential water contamination by catalysts. Overall, this study not only provided a deep insight on Fe/Mo-triggered PMS activation process, but also provided an effective and reliable approach for the treatment of DNA bases, ARGs, DNA, and ARB in water.
Polycyclic aromatic hydrocarbons (PAHs) are frequently released in aqueous phase by oil spill or from other sources, and photochemical oxidation is one of their major weathering processes. In this study, the photochemical behavior of phenanthrene (PHE, as a representative PAH) were studied and the effects of nitrogenous compounds were evaluated. The results showed that nitrate was an effective photosensitizer for improving the photodegradation of PHE, but the promoting effect was less effective in seawater due to the presence of halogen ions; the ammonia played a negligible role on PHE degradation. The photochemical ionization was a key process for PHE degradation, it can be retarded due to the quenching of triplet excited state by dissolved oxygen, and the inhibition was most prominent in fresh water. The presence of nitrate increased the steady state concentration of •OH from 2.08 × 10−15 M to 1.04 × 10−14 M in fresh water, and from 1.5 × 10−16 M to 2.08 × 10−15 M in seawater. The secondary-order reaction rate constant between PHE and •OH (k•OH,PHE) was determined as 5.70 × 109 M−1 s−1. Similar trend was observed for 1O2. The contribution of •OH to PHE removal was more prominent in fresh water than in seawater due to the quenching effects of halogen, and the increasing of nitrate enlarged the contribution of •OH. Two possible PHE degradation pathways were proposed based on GC-MS analysis and DFT calculation. The Quantitative Structure-activity Relationship (QSAR) evaluation showed that some degradation intermediates were more toxic than PHE, but the total environmental risk was still diminished due to the low percentage of toxic intermediates. This study provided theoretical and experimental insights into the influence of nitrogenous compounds on the photodegradation of PHAs in water environment.
Abstract Aim Significant changes in species elevational ranges in mountains have been repeatedly documented, yet the direction, magnitude and drivers of these shifts remain controversial. Presently, there is still lacking evidence about the general nature of species elevational range shifts in eastern Eurasia in response to anthropogenic climate change. By using historical specimen records and recent field observations for 735 seed plant species across 29 China's mountains, we assessed changes in species' elevational centroids and their drivers. Location China. Time Period 1950–2018. Major Taxa Studied Seed plant species. Methods The elevation records of all sampled occurrences in each mountain during the two time periods were estimated, and the null models were developed to test the sampling bias. Ecological niche models (ENMs) were used to evaluate the relative importance of climate factors in constraining each species distribution. Generalized linear models (GLMs) to test the relationships between the centroid elevational range shifts of species and different divers. Results We found that 54% of the species shifting upward and 46% downhill. However, species' elevational shifts significantly differed among species and mountains. Herbaceous and lowland species moved upward faster than woody and high-elevation species. Species in temperate mountains and in mountains with taller elevational gradients moved upward, while species in subtropical mountains and in mountains with shorter elevational gradients moved downward. Precipitation changes experienced by species, species' climatic adaptations, several species' functional traits and mountain size all contributed to explain the magnitude of species' centroid elevational range shifts. Main Conclusions Our results highlight complex biodiversity redistribution of seed plants across Chinese mountains, not necessarily conforming to the trend of species upward shifts in elevation. Changes in precipitation regimes may blur the simplistic assumption of isotherm tracking. This study fills an important geographic shortfall for our understanding of biodiversity redistribution under anthropogenic climate change.
Decabromodiphenyl ethane (DBDPE) is the main alternative to decabromodiphenyl ether (deca-BDE) in commercial use. However, there is increasing evidence show that DBDPE is a potential persistent organic pollutant, and it has been found ubiquitously in environmental media across China in recent years. Monitoring studies have not been able to determine the overall levels and temporal trends of DBDPE contamination in China, and have been unable to explain how emission patterns can affect their environmental distribution. Therefore, this study estimated the temporal variance of DBDPE emissions and environmental concentrations in five regions of China from 2006 to 2026 using the PROduction-To-EXposure (PROTEX) mass balance model. The results showed that Guangdong Province was the greatest DBDPE pollution hotspot in China due to emissions from plastics manufacturing and e-waste disposal; there was also severe pollution in Shandong Province, where almost all the DBDPE in China is produced. The DBDPE concentrations in indoor and outdoor environments increased substantially in all regions during 2006–2021. Furthermore, in Guangdong Province and Shandong Province, the ratio of indoor/outdoor air concentrations was greater than or close to 1, indicative of significant outdoor emission sources of DBDPE. In contrast, the ratios for the Beijing–Tianjin–Hebei region, East China, and Southwest China were below 1 due to the indoor use of electronic equipment containing DBDPE. The temporal trends of these ratios indicated that DBDPE contamination has gradually spread from high-concentration environments with strong emission sources to low-concentration environments. The outcomes of this study have important implications for the risk assessment of DBDPE use in China and can be used to establish contamination-mitigation actions.
Identifying the policy effect of government subsidies on families is beneficial to alleviate household energy poverty. This study first builds a Propensity Score Matching–Difference-in-Differences (PSM-DID) model and empirically tests the impact of government subsidies on household energy poverty in China based on China Family Panel Studies data from 2016 to 2018. The results show that household energy poverty is considered to have obvious regional differences. Moreover, the results indicate that government subsidies can reduce the probability of household energy poverty by 38.1%. However, the effect of government subsidies in alleviating household energy poverty will vary depending on the specific household situation. It is concluded that subsidies provided by the Chinese government to households can effectively alleviate household energy poverty. Finally, some policy recommendations are proposed based on the results of the empirical analysis.
The discovery of superconductivity in layered MgB2 has renewed interest in the search for high-temperature conventional superconductors, leading to the synthesis of numerous hydrogen-dominated materials with high critical temperatures (Tc) under high pressures. However, achieving a high-Tc superconductor under ambient pressure remains a challenging goal. In this study, we propose a novel approach to realize a high-temperature superconductor under ambient pressure by introducing a hexagonal H monolayer into the hexagonal close-packed magnesium lattice, resulting in a new and stable few-hydrogen metal-bonded layered magnesium hydride (Mg4)2H1. This compound exhibits superior ductility compared to multi-hydrogen, cuprate, and iron-based superconductors due to its metallic bonding. Our unconventional strategy diverges from the conventional design principles used in hydrogen-dominated covalent high-temperature superconductors. Using anisotropic Migdal–Eliashberg equations, we demonstrate that the stable (Mg4)2H1 compound is a typical phonon-mediated superconductor, characterized by strong electron–phonon coupling and an excellent Tc of 37 K under ambient conditions, comparable to that of MgB2. Our findings not only present a new pathway for exploring high-temperature superconductors but also provide valuable insights for future experimental synthesis endeavors.
Environmental theoretical calculation aims to use computer simulation to assist in solving environmental problems. Herein, we present the guiding principles of environmental theoretical calculation for non-periodic systems. A summary is given of recent progress towards the use of environmental theoretical calculation to reveal the degradation/transformation mechanisms of contaminants in reactions.
Seismic recordings made during the InSight mission 1 suggested that Mars's liquid core would need to be approximately 27% lighter than pure liquid iron 2,3 , implying a considerable complement of light elements. Core compositions based on seismic and bulk geophysical constraints, however, require larger quantities of the volatile elements hydrogen, carbon and sulfur than those that were cosmochemically available in the likely building blocks of Mars 4 . Here we show that multiply diffracted P waves along a stratified core–mantle boundary region of Mars in combination with first-principles computations of the thermoelastic properties of liquid iron-rich alloys 3 require the presence of a fully molten silicate layer overlying a smaller, denser liquid core. Inverting differential body wave travel time data with particular sensitivity to the core–mantle boundary region suggests a decreased core radius of 1,675 ± 30 km associated with an increased density of 6.65 ± 0.1 g cm −3 , relative to previous models 2,4–8 , while the thickness and density of the molten silicate layer are 150 ± 15 km and 4.05 ± 0.05 g cm −3 , respectively. The core properties inferred here reconcile bulk geophysical and cosmochemical requirements, consistent with a core containing 85–91 wt% iron–nickel and 9–15 wt% light elements, chiefly sulfur, carbon, oxygen and hydrogen. The chemical characteristics of a molten silicate layer above the core may be revealed by products of Martian magmatism.
Abstract Aim Pollination is an essential stage of angiosperm reproduction, and the mode of pollination plays a major role in driving evolutionary and ecological responses of plants to environmental changes. However, the effects of climate, evolutionary history and floral traits (i.e. plant sexual systems) on pollination mode variation remain unclear. Here, we explored the biogeographic patterns in pollination mode frequency and tested the hypothesis that insect pollination prevails in warm humid regions with old floras due to high pollinator dependence, whereas wind pollination is more frequent in arid regions with younger floras and is more strongly associated with dioecy. Location China. Time period Since the Last Glacial Maximum. Major taxa studied Angiosperms. Methods Using data on pollination modes and geographic ranges of 29,719 angiosperm species in China, we mapped the biogeographic pattern of pollination mode frequency. Phylogenetic logistic regressions and generalized linear mixed models were employed to evaluate the relative importance of climate, evolutionary history (represented by phylogenetic conservatism and grid-level mean genus age) and sexual systems on variations in pollination modes across species and space. Results Evolutionary history was the strongest correlate of pollination mode variation across species and space. The proportion of insect-pollinated species was higher in humid regions with old floras, but lower in arid regions with young floras. Evolutionary history and temperature dominated variations in pollination mode frequency in humid areas, while precipitation dominated in arid areas. Climate influenced geographic pattern in pollination mode frequency both directly and indirectly via its effects on species richness and plant sexual systems. Main Conclusions Our results showed that geographic pattern in angiosperm pollination mode frequency is dominated by evolutionary history followed by climate, which extended previous findings of climate-driven mechanisms. Our findings demonstrate the importance to incorporate evolutionary history in understanding the mechanisms underlying the functional biogeography of plant traits.
Abstract Aim Climate has been regarded as an important explanation for large-scale species richness patterns. However, the mechanisms underlying the significant variations in species richness?climate relationships across different clades remain to be tested. We explored how niche conservatism, diversification rates and time for speciation influenced species richness?climate relationships between clades. Location The globe. Time Period Present day. Major Taxa Studied Angiosperms. Methods Based on a newly complied database of the global distributions of 288,735 angiosperm species, we used generalized linear models to assess the relationships between species richness of different angiosperm families and climatic factors. We also conducted phylogenetic comparative analysis to test whether niche conservatism, diversification rates and time for speciation affect the variations in species richness?climate relationships. Results We found that temperature seasonality dominated the global angiosperm diversity patterns. Closely related families had more similar species richness?climate relationships than distantly related ones. The discrepancy between the current and ancestral niches of different clades had much stronger effects on variations in species richness?climate relationships than diversification rates and time for speciation. With the increase in the discrepancy between current and ancestral niches, the explanatory power (i.e., R2) of contemporary temperature and precipitation in explaining species richness patterns increased. Main Conclusions Overall, our findings strongly support that niche conservatism dominates the variations in species richness?climate relationships across taxonomic groups. These findings allow better understanding on how large-scale species diversity patterns are formed.
