•SOM rather than soil particle size controls soil water retention in alpine soils.•Two mechanisms of SOM functioning against soil water retention were differentiated.•Pedogenic A horizon is critical ...in maintaining the alpine ecosystem.•Soil hydrological functions were discussed from multi-perspectives.
Soil water retention influences many soil properties and soil hydrological processes. The alpine meadows and steppes of the Qilian Mountains on the northeast border of the Qinghai-Tibetan Plateau form the source area of the Heihe River, the second largest inland river in China. The soils of this area therefore have a large effect on water movement and storage of the entire watershed. In order to understand the controlling factors of soil water retention and how they affect regional eco-hydrological processes in an alpine grassland, thirty-five pedogenic horizons in fourteen soil profiles along two facing hillslopes in typical watersheds of this area were selected for study. Results show that the extensively-accumulated soil organic matter plays a dominant role in controlling soil water retention in this alpine environment. We distinguished two mechanisms of this control. First, at high matric potentials soil organic matter affected soil water retention mainly through altering soil structural parameters and thereby soil bulk density. Second, at low matric potentials the water adsorbing capacity of soil organic matter directly affected water retention. To investigate the hydrological functions of soils at larger scales, soil water retention was compared by three generalized pedogenic horizons. Among these soil horizons, the mattic A horizon, a diagnostic surface horizon of Chinese Soil Taxonomy defined specially for alpine meadow soils, had the greatest soil water retention over the entire range of measured matric potentials. Hillslopes with soils having these horizons are expected to have low surface runoff. This study promotes the understanding of the critical role of alpine soils, especially the vegetated surface soils in controlling the eco-hydrological processes in source regions of the Heihe River watershed.
Due to the increased frequency of extreme weather events and the implementation of the China's dual-carbon target, thermal power companies have been under pressure to construct green infrastructure ...and to actively pursue low-carbon transformation in response to stricter environmental regulations. This research thus selects 30 listed thermal power enterprises in China as study objects and assesses their green investment efficiency in the low-carbon transition process using three-stage DEA evaluation model with environmental regulation as an exogenous variable. Based on this, a benchmark regression model is used to corroborate the relationship between environmental regulation and green investment. Simultaneously, we carry out analysis to compare the correlation between thermal power firms' green investment efficiency and their focus on green investments. The results show in terms of total efficiency that environmental regulation significantly improves the total efficiency of 80% of thermal power enterprises compared to the absence of this exogenous variable. With the addition of environmental regulation, firms' total efficiency declines gradually in general from 2018 to 2022, with the mean value of efficiency falling by 0.068. In terms of stage-specific efficiency, the efficiency of the green investment stage of the majority of firms is between 0.3 and 0.6, which is much lower than that of the operational stage and the market performance stage. In terms of sub-indicator efficiency, both green investment efficiency and social donation efficiency among thermal power enterprises show obvious polarization, with 30% of them having an efficiency of 1 and 30% less than 0.1. In terms of green investment focus, thermal power unit renovation has a more obvious role in boosting the green investment efficiency of thermal power enterprises than do wind power and photovoltaic projects. Therefore, both governmental departments and thermal power enterprises need to take active measures in order to achieve green transformation from the perspective of green investment efficiency. Through the segmentation of important projects of green investment, this paper provides a reasonable investment direction reference for the sustainable transformation of China's thermal power industry. It also provides a rich and novel theoretical basis for the Chinese government to further improve the relevant environmental protection laws and regulations of thermal power industry.
Microcystis, the dominant species among cyanobacterial blooms, normally forms colonies under natural conditions but exists as single cells or paired cells in axenic laboratory cultures after ...long-term cultivation. Here, a bloom-forming Microcystis aeruginosa strain CHAOHU 1326 was studied because it presents a colonial morphology and grows on the water surface during axenic laboratory culturing. We first examined the morphological features of strain CHAOHU 1326 and three other unicellular M. aeruginosa strains FACHB-925, FACHB-940, and FACHB-975 cultured under the same conditions by scanning and transmission electron microscopy. Then, we compared the extracellular polysaccharide (EPS)-producing ability of colonial strain CHAOHU 1326 to that of the three unicellular M. aeruginosa strains, and found that strain CHAOHU 1326 produced a higher amount of EPS than the other strains during growth. Moreover, based on genome sequencing, multiple gene clusters implicated in EPS biosynthesis and a cluster of 12 genes predicted to be involved in gas vesicle synthesis in strain CHAOHU 1326 were detected. These predicted genes were all functional and expressed in M. aeruginosa CHAOHU 1326 as determined by reverse transcription PCR. These findings provide a physiological and genetic basis to better understand colony formation and buoyancy control during M. aeruginosa blooming.
Nuclear fission produces 400 GWe which represents 11% of the global electricity output. Uranium is the essential element as both fission fuel and radioactive waste. Therefore, the recovery of uranium ...is of great importance. Here, an in situ electrolytic deposition method to extract uranium from aqueous solution is reported. A functionalized reduced graphene oxide foam (3D‐FrGOF) is used as the working electrode, which acts as both a hydrogen evolution reaction catalyst and a uranium deposition substrate. The specific electrolytic deposition capacity for U(VI) ions with the 3D‐FrGOF is 4560 mg g−1 without reaching saturation, and the Coulombic efficiency can reach 54%. Moreover, reduction of the uranium concentration in spiked seawater from 3 ppm to 19.9 ppb is achieved, which is lower than the US Environmental Protection Agency uranium limits for drinking water (30 ppb). Furthermore, the collection electrode can be efficiently regenerated and recycled at least nine times without much efficiency fading, by ejecting into 2000 ppm concentrated uranium solution in a second bath with reverse voltage bias. All these findings open new opportunities in using free‐standing 3D‐FrGOF electrode as an advanced separation technique for water treatment.
A reusable 3D functionalized reduced graphene oxide foam (3D‐FrGOF) is used as an in situ electrolytic deposition electrode to extract uranium from contaminated water. The specific U(VI) extraction capacity is 4560 mg g−1, and the Coulombic efficiency is 54%. Moreover, uranium in spiked seawater is reduced from 3 ppm to less than 19.9 ppb (the US Environmental Protection Agency drinking water limit is 30 ppb).
Recycling of the major components from spent Li-ion batteries (LIBs) is considered desirable to prevent environmental pollution and recycle valuable metals. The present work investigates a novel ...process for recovering Co and Li from the cathode materials (containing LiCoO2 and Al) by a combination of ultrasonic washing, calcination, and organic acid leaching. Copper can also be recovered from the anode materials after they are manually separated from the cathode. Ascorbic acid is chosen as both leaching reagent and reducing agent to improve the Co recovery efficiency. Leaching efficiencies as high as 94.8% for Co and 98.5% for Li are achieved with a 1.25 mol L−1 ascorbic acid solution, leaching temperature of 70 °C, leaching time of 20 min, and solid-to-liquid ratio of 25gL−1. The acid leaching reaction mechanism has been preliminarily studied based on the structure of ascorbic acid. This method is shown to offer an efficient way to recycle valuable materials from spent LIBs, and it can be scaled up for commercial application.
► We report an ultrasonic-assisted hydrometallurgical technique. ► Ascorbic acid is chosen as both leaching reagent and reducing agent. ► This technique avoids use of the traditional reducing agent H2O2. ► Leaching efficiencies are as high as 94.8% for Co and 98.5%. ► The acid leaching reaction mechanism has been preliminarily studied.
Sodium-ion batteries are promising alternatives to lithium-ion batteries for large-scale applications. However, the low capacity and poor rate capability of existing anodes for sodium-ion batteries ...are bottlenecks for future developments. Here, we report a high performance nanostructured anode material for sodium-ion batteries that is fabricated by high energy ball milling to form black phosphorus/Ketjenblack–multiwalled carbon nanotubes (BPC) composite. With this strategy, the BPC composite with a high phosphorus content (70 wt %) could deliver a very high initial Coulombic efficiency (>90%) and high specific capacity with excellent cyclability at high rate of charge/discharge (∼1700 mAh g–1 after 100 cycles at 1.3 A g–1 based on the mass of P). In situ electrochemical impedance spectroscopy, synchrotron high energy X-ray diffraction, ex situ small/wide-angle X-ray scattering, high resolution transmission electronic microscopy, and nuclear magnetic resonance were further used to unravel its superior sodium storage performance. The scientific findings gained in this work are expected to serve as a guide for future design on high performance anode material for sodium-ion batteries.
Despite the high theoretical capacity of lithium–sulfur batteries, their practical applications are severely hindered by a fast capacity decay, stemming from the dissolution and diffusion of lithium ...polysulfides in the electrolyte. A novel functional carbon composite (carbon‐nanotube‐interpenetrated mesoporous nitrogen‐doped carbon spheres, MNCS/CNT), which can strongly adsorb lithium polysulfides, is now reported to act as a sulfur host. The nitrogen functional groups of this composite enable the effective trapping of lithium polysulfides on electroactive sites within the cathode, leading to a much improved electrochemical performance (1200 mAh g−1 after 200 cycles). The enhancement in adsorption can be attributed to the chemical bonding of lithium ions by nitrogen functional groups in the MNCS/CNT framework. Furthermore, the micrometer‐sized spherical structure of the material yields a high areal capacity (ca. 6 mAh cm−2) with a high sulfur loading of approximately 5 mg cm−2, which is ideal for practical applications of the lithium–sulfur batteries.
A composite that consists of carbon‐nanotube‐interpenetrated mesoporous nitrogen‐doped carbon spheres (MNCS/CNT) can strongly chemisorb polysulfides and was used as a cathode material for lithium–sulfur batteries. Moreover, the highly conductive nitrogen‐doped carbon material enables direct and easy redox reactions of the adsorbed polysulfides, which leads to good electrode kinetics.
Coastal soils are particularly sensitive to nonnative species invasion. In this context, spatially explicit soil information is essential for improving the knowledge of the role of soil in changing ...environments, supporting coastal sustainable management. Synthetic-aperture radar (SAR) data provides an attractive opportunity to monitor soil because the acquisition of images is independent of weather and daylight. However, SAR has not been commonly used for soil prediction. In this study, we firstly investigated the temporal variation of vegetation canopy and the soil-vegetation relationship using Sentinel-1 data in an invaded coastal wetland. And then we built 3D models to predict soil properties at multiple depths. A total of 16 Sentinel-1 images were acquired in a growing season. A series of soil physicochemical properties were examined including soil bulk density, texture, organic/inorganic carbon, pH, salinity, total nitrogen, and C/N ratio, relating to three depth layers in the top 1-m depth. Our results showed that time-series Sentinel-1 data can capture temporal characteristics of vegetation, and VH/VV was more sensitive to the vegetation growth than VH and VV. The soil-vegetation relationship captured by time-series SAR data was beneficial to predict soil properties, especially for soil chemical properties. The models provided permissible prediction accuracy, with an average RPD of 0.99. We concluded that the prior understanding of the temporal variation of SAR data is essential for developing practical soil prediction strategy. Our results highlight that SAR has the potential to predict a diverse set of soil properties in coastal wetlands with dense vegetation cover.
We experimentally investigated methods of enhancing the small-signal responsivity of a silicon pin microring photodetector based on two-photon absorption for detecting small optical signals in the ...telecommunication wavelength range. Two approaches are demonstrated, the first exploiting the bistability effect in the nonlinear microring resonator while the second employing an optical bias at a different wavelength to increase the differential responsivity. We achieved a small-signal responsivity of 180 mA/W with the first approach and 141 mA/W with the second approach, both of which represent almost 10-fold enhancement over direct detection of small optical signals by the same silicon pin microring detector. Our techniques have potential applications in amplitude demodulation, heterodyne detection, and optical power monitoring in WDM communication channels.
The health crisis caused by severe multidrug resistance increasingly compels the exploitation of new alternative antibacterial drugs. A library of structurally unique dihydropyrimidinone imidazoles ...as novel potential antibacterial agents was developed with the aim to confront drug resistance. Some target compounds exhibited strong antibacterial activities, especially, sulfamethoxazole hybridized dihydropyrimidinone imidazole 8b was found to be extremely active against multidrug-resistant K. pneumonia and A. baumanii at a low concentration of 0.5 μg/mL, which outperformed norfloxacin even clinafloxacin. This active compound not only exhibited low cytotoxicity to mammalian cells (human red blood cells, HepG2 and ECs), but also possessed rapid bactericidal property, good biofilm inhibition ability, and a low propensity to induce K. pneumonia and A. baumanii resistance. Further studies revealed that the inhibitory effect of the active compound 8b might be achieved by disrupting membrane integrity, increasing ROS generation, reducing GSH activity and interacting with DNA. These findings provided a bright hope for developing dihydropyrimidinone imidazoles to combat emergent drug resistance.
A type of novel structural dihydropyrimidone imidazoles with antibacterial potential was exploited. Experimental investigation with membrane destruction, ROS accumulation, loss of GSH activity, DNA interaction suggested possible antibacterial mechanisms. Display omitted
•Novel dihydropyrimidone imidazole hybrids as antibacterial agents were developed.•Compound 8b showed low MIC value of 0.5 μg/mL against K. pneumonia and A. baumanii.•Compound 8b displayed no obvious resistance, favorable antibiofilm activity and high biosafety.•Compound 8b caused membrane disruption, accumulation of ROS and loss of GSH activity.•Compound 8b could form a supramolecular complex with DNA to hinder DNA replication.
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