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Wastewater reclamation and reuse is an increasing global project, while the reclamation treatment on wastewater does not completely remove all pollutants in water. The residual pollutants in reclaimed water would cause potential risk on human health and ecosystem safety during the long-term use. It is impossible to analyze and control all pollutants one by one in practice, therefore, identification and control of priority pollutants will be efficient strategy to ensure the safe use of reclaimed water. An integrated three-step methodology for identifying priority pollutants in reclaimed water was proposed in this study. First, a comprehensive literature survey on the occurrence of pollutants in reclaimed water was conducted, and a dataset DPR for pollutants occurrence in reclaimed water was established, containing 1,113 pollutants. Second, 611 chemicals that had been recommended as hazardous pollutants for various water bodies in previous literatures were summarized, and a dataset DHP for hazardous pollutants in water was obtained. Third, meta-analysis on these two datasets (DPR and DHP) was performed, a new dataset DHPR for hazardous pollutants in reclaimed water was established, including 265 candidates. Finally, 59 substances out of dataset DHPR were identified as priority pollutants for reclaimed water based on their recommendation frequency. It is expected that this synthetical methodology will provide powerful support for scientific evaluating and managing water pollution and ensuring safe use of reclaimed water.

With the development of the preparation methods of low dimensional materials, one-dimensional (1D) nanomaterials present enormous benefits in hydrogen sensing area. This work reviews the up-to-date research progress of 1D nanomaterials in the field of hydrogen gas sensing and its three routes via material, morphology and post-treatment to enhanced sensing performances. Besides, the mechanism of hydrogen gas sensing, the differences of enhancement effect between material synthesis, morphology control and post-treatment schemes are analyzed. Finally, the prospects and challenges of 1D nanomaterials in hydrogen gas sensing are discussed and outlooked.

In this paper, a novel hybrid structure of Pd doped ZnO/SnO2 heterojunction nanofibers with hexagonal ZnO columns was one step synthesized from electrospun precursor nanofibers. Due to the synergistic effect of hexagonal ZnO, SnO2 and Pd, the structure exhibited excellent hydrogen (H2) gas sensing properties. At low-temperature of 120 °C, the response (Ra/Rg) to 100 ppm H2 gas exceeded 160, the response/recovery time was only 20 s and 6 s respectively and the limit of detection was only 0.5 ppm. Meanwhile, it also had good selectivity for H2 gas and excellent linearity. In addition, the materials were characterized by XRD, FESEM, HRTEM, XPS, and the synthesis mechanism and gas sensing mechanism were proposed.

In this study, ZnO–SnO2 heterojunction nanofibers were fabricated using electrospinning and treated by Ar plasma. The post treatment demonstrated the ability to regulate adsorbed oxygen of nanofibers and thus affecting the gas sensing performance. The results revealed that the gas sensing performances increased with the increase of plasma treatment time at first, then showed a downward trend. The setting for the best H2 gas performance was 20 min of plasma treatment, under which the response of the sample was 80% higher and the response time was two thirds shorter than those of the untreated sample. The explanation can be that appropriate plasma treatment can increase the oxygen vacancy on the surface of heterojunction nanofibers as well as the resistance modulation range in the air; however, excessive plasma treatment can result in the reduction of the resistance modulation range in the air by reducing the metal oxide to metal.

Pd-doped SnO2 nanofibres were prepared by electrospinning and magnetron sputtering. It was found that the efficiency of gas sensing properties in these fibres depends primarily on the density of oxygen vacancies, which can be regulated by plasma treatment. We demonstrated that moderate plasma treatment can increase the oxygen vacancy as well as improve the gas sensing performance of SnO2. However, excessive plasma treatment led to the production of other substances that deteriorated the gas sensing performance. Furthermore, the best results for hydrogen gas sensing were obtained when the nanofibres were subjected to plasma treatment for 1 min. The fabricated material demonstrated a response of more than 53 for 500 ppm hydrogen at the optimum temperature (130 °C), which is a significant improvement as compared to sensors without plasma treatment. Evidently, plasma treatment is an effective method to further enhance the sensing properties of the fabricated nanofibres.

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis. However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water. Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water. Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards. Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended. Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well. Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.

River-reservoir systems have become ubiquitous among modern global aquatic environments due to the widespread construction of dams. However, little is known of antibiotic resistance gene (ARG) distributions in reservoir-river systems experiencing varying degrees of anthropogenic impacts. Here, the diversity, abundance, and spatial distribution of ARGs were comprehensively characterized along the main stem of the Minjiang River, a typical subtropic reservoir-river system in Southeast China using high-throughput quantitative PCR. A total of 252 ARG subtypes were detected from twelve sampling sites that were dominated by aac(3)-Via, followed by czcA, blaTEM, and sul1. Urban river waters (sites S9-S12) harbored more diverse ARGs than did the reservoir waters (sites S1-S7), indicating more serious antibiotic resistance pollution in areas with larger population densities. Dam construction could reduce the richness and absolute abundance of ARGs from upstream (site S7) to downstream (site S8). Urban river waters also harbored a higher proportion of mobile genetic elements (MGEs), suggesting that intensive human activities may promote ARG horizontal gene transfers. The mean relative abundance of Proteobacteria that could promote antibiotic resistance within microbial communities was also highest in urban river waters. Variance partitioning analysis indicated that MGEs and bacterial communities could explain 67.33%, 44.7%, and 90.29% of variation in selected ARGs for the entire watershed, aquaculture waters, and urban river waters, respectively. These results further suggest that urban rivers are ideal media for the acquisition and spread of ARGs. These findings provide new insights into the occurrence and potential mechanisms determining the distributions of ARGs in a reservoir-river system experiencing various anthropogenic disturbances at the watershed scale.

In this paper, we present the synthesis of novel three-dimensional SnO2/MoS2 nanocomposites via electrospinning combined with a hydrothermal method and their application to CH4 gas detection. Morphological characterization proved that the flower-like MoS2 structures were successfully connected to the surface of porous SnO2 nanofibers. The CH4 gas-sensing test results indicated that the gas-sensing properties of SnO2/MoS2 nanocomposites were better than those of pure MoS2; the SnO2/MoS2 nanocomposites exhibited lower optimal operation temperature and higher gas response. Such excellent performance is mainly attributable to the special hierarchical structure and the existence of n–n junctions between SnO2 and MoS2.

Triphenyl phosphate (TPhP), a prevalent pollutant in the aquatic environment, has been reported to induce neurotoxicity (e.g., a suppression in locomotor activity) in fish larvae, posing a great threat to fish populations. However, the underlying mechanism was not fully revealed. In this study, the Oryzias melastigma larvae (21 dph) were exposed to waterborne TPhP (20 and 100 μg/L) for 7 days and a decreased locomotor activity was found. After exposure, the brain transcriptome and communities of gut microbiota were investigated to explore the potential mechanism underlying the suppressed locomotor activity by TPhP. The results showed that 1160 genes in the brain were dysregulated by TPhP, of which 24 genes were identified as being highly associated with the neural function and development (including nerve regeneration, neuronal growth and differentiation, brain ion homeostasis, production of neurotransmitters and etc), suggesting a general impairment in the central nervous system. Meanwhile, TPhP caused disorders in the gut microbiota. The relative abundance of Gammaproteobacteria and Alphaproteobacteria, which can influence the brain functions of host via the microbiota-gut-brain axis, were significantly altered by TPhP. Furthermore, the Redundancy analysis (RDA) revealed positive correlations between the intestinal genera Ruegeria, Roseivivax and Nautella and the dysregulated brain genes by TPhP. These results suggest that TPhP might impair the central nervous system of the O. melastigma larvae not only directly but also through the microbiota-gut-axis (indirectly), contributing to the suppressed locomotor activity. These findings enrich our mechanistic understanding of the toxicity of TPhP in fish larvae and shed preliminary light on the involvement of microbiota-gut-brain axis in the neurotoxicity of environmental pollutants.

Antibiotics and nanoplastics are two prevalent pollutants in oceans, posing a great threat to marine ecosystems. As antibiotics and nanoplastics are highly bioconcentrated in lower trophic levels, evaluating their impacts on marine organisms via dietary exposure route is of great importance. In this study, the individual and joint effects of dietborne sulfamethazine (SMZ) and nanoplastic fragments (polystyrene, PS) in marine medaka (Oryzias melastigma) were investigated. After 30 days of dietary exposure, 4.62 mg/g SMZ decreased the Chao1 index (60.86% for females and 26.85% for males) and the Shannon index (68.95% for females and 65.05% for males) and significantly altered the structure of gut microbial communities in both sexes. The female fish exposed to 4.62 mg/g SMZ exhibited higher intestinal sod (43.5%), cat (38.5%) and gpx (39.6%) transcripts, indicating oxidative stress in the gut. PS alone at 3.45 mg/g slightly altered the composition of the gut microbiota. Interestingly, the mixture of SMZ and PS caused more modest effects on the gut microbiota and intestinal antioxidant physiology than the SMZ alone, suggesting that the presence of PS might alleviate the intestinal toxicity of SMZ in a scenario of dietary co-exposure. This study helps better understand the risk of antibiotics and nanoplastics to marine ecosystems.

A method of determining high fluence rate for D-T neutron source by using two long counters is introduced. One long counter contains a BF3 proportional counter, and a response of 1.1 cm2 is determined by calibration. The other long counter contains a gamma compensated boron neutron ionization chamber, and a response of 2.06e-5 cm2 is determined by comparing with the results of long counter containing BF3 proportional counter. By appropriately arranging the two long counters, fluence measurements are performed at the high intensity D-T neutron generator (HINEG). The results of the experimental characterization to the long counter are presented at this paper.

High-spin states in 84Rb are studied by using the 70Zn(18O, p3n)84Rb reaction at a beam energy of 75 MeV. Three high-lying negative-parity bands are established, whose level spacings are very regular, i.e., there is no signature splitting. The dipole character of the transitions of these three bands is assigned by the γ-γ directional correlations of oriented states (DCO) intensity ratios and the multipolarity M1 is suggested by analogy with multiparticle excitations in neighboring nuclei. Strong M1 and weak or no E2 transitions are observed. All these characteristic features show they are magnetic rotational bands.

Ionic conduction is a critical parameter to evaluate the electrical performance of biological dielectric liquids. In this work, detailed molecular dynamics (MD) simulations were carried out to reveal both drift mechanisms of ions (H3O+, Cu2+, OH– and Cl-) and local structure evolution characteristics in biological dielectric liquids under external electric fields. The drift velocities of all ionic species increase nonlinearly with the addition of static electric fields. At relatively low field regimes, the structural cages formed by corresponding biological dielectric molecules are found to reduce ion transport. Above certain field thresholds, the accelerated ions impart appreciable energy to the surrounding molecular segments, making the binding of the cages broken. As such, the electric motion as a replacement of the thermal motion is eventually taken place. The computed thresholds are 0.97 V/nm, 0.645 V/nm, 0.67 V/nm, and 0.77 V/nm for H3O+, Cu2+, OH–, and Cl-, respectively. Additionally, given the electrostatic potential feature of biological dielectric molecules, the structural cages have greater advantages in limiting cationic migration, in which the binding effect for cations is more stable and persistent. The results provide a helpful guideline for designing the next-generation biological dielectric liquids.

Vegetable oils, mainly composed of triacylglycerol molecules, have been widely studied as new insulation materials in the recent years. In this work, we study the electronic properties of various triacylglycerol molecules with different degree of unsaturation by density functional theory (DFT). The ionization potential (IP), electron affinity (EA), and electron trap are estimated by theoretical analysis and experiments. The results show that the C atoms of cis C C double bond make the primary contribution to the highest occupied molecular orbital (HOMO) of unsaturated triacylglycerol molecule; the IPs of fully unsaturated triacylglycerol molecules are almost confined to the narrow ranges from 7.30 to 7.45 eV in gas-phase and from 6.77 to 6.84 eV in liquid-phase correspond to LnLnLn and OOO molecules, respectively; the atoms of ester group and neighboring atoms make the primary contribution to the lowest unoccupied molecular orbital (LUMO) of both saturated and unsaturated triacylglycerol molecules; the EAs of triacylglycerol molecules are confined to the narrow ranges from −0.34 to −0.18 eV and the chemical trap is estimated to be 0–0.16 eV; the total trap is 0.32–0.36 eV. The IP distribution character and shallow trap feature maybe the main causes that vegetable oils demonstrate a low resistance against the fast streamers. The work can provide theoretical basis to molecular modification for performance improvement of vegetable insulating oils.

Moisture is a significant factor that affects the insulation performance of outdoor high-voltage insulators in power systems. Accumulation of water droplets on insulators causes severe problems such as flashover of insulators and power outage. In this study, we develop a method to fabricate a micro/nano hierarchical super hydrophobic surface. The as-prepared super hydrophobic surface exhibits a water contact angle (WCA) of 160.4 ± 2°, slide angle (SA) less than 1° and surface free energy (SFE) of 5.99 mJ/m 2 . We investigated the electrohydropdynamic behavior of water droplet on a horizontal super hydrophobic surface compared with hydrophobic RTV silicone rubber surface which was widely used as anti-pollution coating or shed material of composite insulator. Results show that water droplet tended to a self-propelled motion on the super hydrophobic surface while it tended to elongate and break up on the RTV surface. The micro/nano hierarchical surface structure and chemical components with low surface free energy of the super hydrophobic surface jointly contributed to the reduction of skin fraction drag and subsequently made it possible for the motion of water droplet driven by electric field. Furthermore, the self-propelled motion of water droplets could also sweep away contaminations along its moving trace, which provides super hydrophobic surface a promising anti-pollution prospect in power systems.

As a non-renewable resource, mineral oil has been re-evaluated for its value and suitability as the coolant and insulator in transformers because of its environmental unfriendliness, fire hazards, and operating efficiency dissatisfaction. As a result, alternative dielectric liquids meeting the demands for more reliable, safer, and cleaner energy has been a critical need. Plant-based insulating fluids, non-toxic to the environment and ultimately biodegradable, have been flowing into the mainstream for achieving cost efficiencies, performance advantages, and enhancing safety. With more than 20 years of field experience, plant-based oils are now employed in more than 600,000 transformers worldwide, and have been established an enviable performance track record. Far from being just a mineral oil replacement, but more significantly, plant-based oils have filled a gap in some specific application scenarios where mineral oils fail to satisfy the fire-safety and environmental standards. This article reviews the research status of plant-based insulating fluids for transformer, including both challenges and outlook circa 2020. Plant-based oils have many inherent advantages over mineral oil, but also have numerous and unique challenges.

In this paper, Pd/ZnO–SnO2 hollow nanofibers prepared by electrospinning and magnetron sputtering. The sensing materials exhibited extraordinary hydrogen (H2) sensing behavior – the response reached 171 at 270 °C, and besides, the response time and recovery time were as low as 19 s and less than 1 s at 240 °C, with steady high selectivity and good repeatability. Such an enhanced sensing performance could be attributed to the Pd/ZnO/SnO2 ternary heterojunctions formed in the hollow nanofibers. Moreover, the materials were studied by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and especially the morphology formation process was further explained. The existence of Pd was confirmed to increase the resistance modulation range of heterojunction. In addition, the gas sensing mechanism based on the structure was proposed.

Nanoparticles can generate charge carrier trapping and reduce the velocity of streamer development in insulating oils ultimately leading to an enhancement of the breakdown voltage of insulating oils. Vegetable insulating oil-based nanofluids with three sizes of monodispersed Fe3O4 nanoparticles were prepared and their trapping depths were measured by thermally stimulated method (TSC). It is found that the nanoparticle surfactant polarization can significantly influence the trapping depth of vegetable insulating oil-based nanofluids. A nanoparticle polarization model considering surfactant polarization was proposed to calculate the trapping depth of the nanofluids at different nanoparticle sizes and surfactant thicknesses. The results show the calculated values of the model are in a fairly good agreement with the experimental values.

In this paper, the influence of porosity on the stability of charge and piezoelectric d33 coefficient for porous PTFE electrets is studied by using measurements of isothermal surface potential decay, quasi-static direct piezoelectric coefficient, elastic (compression) modulus and a leakage current through porous and non-porous PTFE samples during corona charging, analyses of open-circuit thermally stimulated discharge current spectra, X-ray diffraction spectra and differential scanning calorimetry. The results point out that with the increase of porosity, the stability of charge deposited in the film and the piezoelectricity of the film are improved in a certain range of porosity. The reasons for the influence of porosity on the thermal stability of the charge storage and piezoelectricity are also investigated. Our results also demonstrate that the improvement of the thermal stability of the piezoelectric coefficient at increasing porosity is due to improved thermal charge stability and the improved stability of the mechanical properties of the material. At the same time, the limitation of the improvement of charge storage and piezoelectricity of a PTFE film with very high porosity is discussed.