Study on water loss settlement law of loose aquifer based on distributed optical fiber

Indirect water loss caused by disturbance from coal mining can cause compression of loose layers and surface subsidence, which poses a threat to coal mine safety. To analyze the effects of such non-mining factors on water loss and subsidence of loose aquifers, the study area was divided into seven layers from top to bottom based on existing geological and hydrological data. Using distributed fiber optic monitoring technology, hydrological observation techniques, and soil mechanics experiments, the loose aquifer in the study area was comprehensively observed and the deformation characteristics of each layer under non-mining conditions were analyzed. The weakening law of the deep aquitard was explored, and the relationship between the deformation of the deep aquifer and the water head height of that layer was determined. The results show that: ① continuous compression of the fourth aquifer and its upper part of the aquitard is the main cause of surface subsidence in the study area. The two layers that contribute the most to the deformation of the strata are the fourth and first aquifers, with the latter showing seasonal deformation characteristics. The fourth aquifer exhibits a continuous subsidence trend during the observation period. ② By combining hydrological boreholes, distributed fiber optic and soil mechanics experiments, monitoring of the degree of clay weakening of the target layer was achieved. The clay layer above the fourth aquifer in the study area is weakened by the impact of the groundwater in the fourth aquifer. The degree of weakening is inversely proportional to the burial depth and directly proportional to the permeability of the groundwater, and the weakening of the clay layer will cause compression of the aquitard at the top of the aquifer and exacerbate surface subsidence. ③ The deformation of the fourth aquifer is consistent with the trend of changes in the water head of the fourth aquifer, and the two are linearly related. The observation results are in agreement with the theoretical calculation results, indicating that water loss from the fourth aquifer is the main cause of its compression deformation

One-step carbothermal synthesis of super nanoadsorbents for rapid and recyclable wastewater treatment

As a potential magnetic super adsorbent in wastewater treatment, Fe3O4 has been re-searched intensively up to date. However, its key problem of poor comprehensive magnetic properties is still challenging. In this work, an effective solution to this problem has been developed by a one-step carbothermal synthesis of Fe3O4 crystals, which are merited with pure-stoichiometry (FeO-phase free), high crystallinity, small-size (~10 nm), strong magnetism and sensitive magnetic response. The unveiled saturation magnetization of Fe3O4 nanoparticles reaches as high as 90.32 emu·g−1, and the fastest magnetic response time is as short as only 5 s. Such magnetic Fe3O4 super adsorbents exhibit outstanding performance when applied as an adsorbent for wastewater treatment. They can quickly and effectively adsorb methylene blue with an adsorption capacity of 62.5 mg·g−1, which is much higher than that of Fe3O4 adsorbents prepared by other methods reported in the literature. Importantly, this capacity is refreshable after removing the adsorbed methylene blue just by ultrasonic cleaning. With such combined outstanding magnetic properties and recyclable adsorption capacity, the problems associated with the conventional adsorbent solid–liquid separation could be resolved, thus making a forward development towards industrial wastewater treatment.This work was supported by the Natural Science Foundation of China (NSFC, 51404181); the Fok Ying Tung Education Foundation (171101); the Youth Innovation Team of Shaanxi Universities (2019-2022); the Top young talents project of “special support program for high level talents” in Shaanxi Province of China (2018-2023); the ANU Futures Scheme (Q4601024); and the Australian Research Council (DP190100295, LE190100014)

Three-dimensional graphene materials : preparation, structures and application in supercapacitors

Three-dimensional (3D) graphene materials (3DGMs) are of great importance due to their unique properties and practical applications. A number of 3DGMs with novel structures have been developed in recent years. This review presents the current progress of 3DGMs. After introducing the preparation strategies of 3DGMs, we summarize the reported 3DGMs based on their different structures, and then focus on the description of their preparation methods, properties and applications. Lastly, the applications of 3D graphene-based materials in supercapacitors are described.Published versio

Electromagnetic interference assessment of a train–network–pipeline coupling system based on a harmonic transmission model

Abstract The harmonics and resonance of traction power supply systems (TPSSs) aggravate the electromagnetic interference (EMI) to adjacent metallic pipelines (MPs), which has aroused widespread concern. In this paper, an evaluation method on pipeline interference voltage under harmonic induction is presented. The results show that the Carson integral formula is more accurate in calculating the mutual impedance at higher frequencies. Then, an integrated train–network–pipeline model is established to estimate the influences of harmonic distortion and resonance on an MP. It is revealed that the higher the harmonic current distortion rate of the traction load, the larger the interference voltage on an MP. Particularly, the interference voltage is amplified up to 7 times when the TPSS resonates, which is worthy of attention. In addition, the parameters that affect the variation and sensitivity of the interference voltage are studied, namely, the pipeline coating material, locomotive position, and soil resistivity, indicating that soil resistivity and 3PE (3-layer polyethylene) anticorrosive coating are more sensitive to harmonic induction. Field test results show that the harmonic distortion can make the interference voltage more serious, and the protective measures are optimized

Heterogeneous bimetallic sulfides based seawater electrolysis towards stable industrial-level large current density

Direct seawater electrolysis is an attractive technology for scalable hydrogen production as well as seawater desalination, which however demands efficient and robust anodic catalysts that can sustain oxygen evolution reaction (OER) against chloride corrosion. Here we report an outstanding anodic catalyst consisting of threedimensional standing arrays of hetero-lateral Ni3S2/Co3S4 (NiCoS) nanosheets uniformly grown on Ni foam for alkaline seawater electrolysis, in which the in-situ derived Ni/Co (oxy)hydroxide surface layer endows abundant active sites and superior resistance to chloride corrosion. Combined with an efficient hydrogen evolution reaction catalyst of Ni/Mo sulfides, a two-electrode electrolyzer affords an industrial-level high current density up to 800 mA cm− 2 at a super low voltage of 2.08 V for overall alkaline seawater splitting steadily over 100 h without chloride corrosion at room temperature. Furthermore, powered by a commercial single III-V triplejunction solar cell, the integrated system demonstrates light-driven overall seawater splitting with an impressive 15.13 % solar-to-hydrogen efficiency. This work is instrumental in the development of seawater electrolysis for sustainable hydrogen production by renewable energy sources.This work was supported by the National Natural Science Foundation of China (Nos. 11974303 and 11574263), the ANU Futures Scheme (Q4601024), the Australian Research Council (DP190100295, LE190100014), the Qing Lan Project of Jiangsu Province (No. 137050317), and the Advanced Talent Development Plan of Yangzhou University (No. 137080051)

Au nanoparticle-modified MoS2 nanosheet-based photoelectrochemical cells for water splitting

The surface plasmon resonance of Au nanoparticle on MoS2 nanosheet is successfully measured by the electron energy-loss spectroscopy. Furthermore, Au-MoS2 composite is developed as the photoanode material in the photo­electronchemical cell (PEC) for water splitting. Compared to the pure MoS2-based PEC, Au-MoS2 based PEC shows the enhanced performance in the photocatalytic water splitting

Fabrication of flexible, all-reduced graphene oxide non-volatile memory devices

A flexible, all reduced graphene oxide non-volatile memory device, with lightly reduced GO as an active layer and highly reduced GO as both top and bottom electrodes, is fabricated by a full-solution process and its performance is characterized. It provides a convenient method to construct other all-carbon devices

Rational synthesis of triangular Au–Ag2S hybrid nanoframes with effective photoresponses

Triangular Au–Ag2S hybrid nanoframes were successfully synthesised by using Ag nanoprisms as templates through gold coating, etching and sulfuration. These Au–Ag2S hybrid nanoframes exhibit effective photocurrent responses for potential photoelectrochemical applications

Graphene-Based Materials for Solar Cell Applications

Graphene has attracted increasing attention due to its unique electrical, optical, optoelectronic, and mechanical properties, which have opened up huge numbers of opportunities for applications. An overview of the recent research on graphene and its derivatives is presented, with a particular focus on synthesis, properties, and applications in solar cells