Distribution, sources, ecological and human health risks of organic ultraviolet filters in coastal waters and beach deposits in Hainan, China.

Organic ultraviolet filters (OUVFs) are extensively incorporated into both cosmetic items and industrial products and have been commonly found in water ecosystems. This study aims to examine the environmental levels, sources, ecological and human health risks of 14 commonly used OUVFs both in coastal water and beach deposit samples collected from the nearshore regions of Hainan Island and the South China Sea. This is first study highlighting the contamination of OUVFs in Hainan Island and utilizing economic and tourism data to confirm the potential source of OUVF pollution in costal aquatic and coastal ecosystem. Along the coastal tourist regions of Hainan Island, the median concentrations in coastal waters and beach deposits of these OUVFs fall within the range from 1.2 to 53.2 ng/L and 0.2-17.0 ng/g dw, respectively. In coastal water and beach deposit, the concentration of BP-3 was the highest, with median concentrations of 53.2 ng/L and 17.0 ng/g dw, respectively. Regarding human health risks, the daily intake of all 14 OUVFs through swimming was found to be 40-48 ng/kg/day. Ecological risk assessment indicates that BP-3 presents a medium risk for marine microalgae with a concurrent low risk for corals. The correlation analysis underscores a substantial interrelation of OUVFs in both coastal waters and beach deposits with various economic indicators, including annual rainfall, overnight tourists, total hotel rooms (unit), room occupancy rate, and sewage treatment capacity.

Tomato plant growth promotion and drought tolerance conferred by three arbuscular mycorrhizal fungi is mediated by lipid metabolism.

Arbuscular mycorrhizal fungi (AMF) can promote plant growth and enhance plant drought tolerance with varying effect size among different fungal species. However, the linkage between the variation and the lipid metabolism, which is exclusively derived from plants, has been little explored thus far. Here, we established AM symbiosis between tomato (Solanum lycopersicum) plants and three AMF species (Rhizophagus intraradices, Funneliformis mosseae, Rhizophagus irregularis) under well watered (WW) or drought stressed (DS) conditions in pot experiment. The plant biomass, chlorophyll fluorescence Fv/Fm, shoot P content and mycorrhizal colonization were determined. Meanwhile, fatty acid (FA) profiles and relative expression of genes encoding for nutrition exchange (SlPT4, SlPT5, RAM2, STR/STR2) in roots were also monitored. DS significantly decreased plant biomass while AMF significantly increased it, with three fungal species varying in their growth promoting capacity and drought tolerance capacity. The growth promoting effect of R. irregularis was lower than those of R. intraradices and F. mosseae, and was associated with higher mycorrhizal colonization and more consumption of lipids. However, the drought tolerance capacity of R. irregularis was greater than those of R. intraradices and F. mosseae, and was associated with less decrease in mycorrhizal colonization and lipid content. We also found that AMF mediated plant drought tolerance via regulating both AM specific FAs and non-AM specific FAs in a complementary manner. These data suggest that lipid metabolism in AM plays a crucial role in plant drought tolerance mediated by AMF.

Distribution characteristics of antibiotic resistance genes and microbial diversity in the inshore aquaculture area of Wenchang, Hainan, China.

The rapid development of marine aquaculture has led to the increased use and release of antibiotics into the marine environment, consequently contributing to the emergence of antibiotic resistance. Information on antibiotic resistance in nearshore marine aquaculture areas remains limited, and research on the microbial composition and potential hosts of antibiotic resistance genes (ARGs) in marine aquaculture areas is scarce. This study used SmartChip real-time fluorescent quantitative PCR and qPCR to quantitatively analyze 44 ARGs and 10 mobile genetic elements (MGEs) genes in 12 sampling points in the nearshore aquaculture area of Wenchang. High-throughput sequencing of 16S rRNA was used to study microbial diversity in the study area, to clarify the correlation between ARGs, MGEs, and microbial diversity, and to determine the possible sources and potential hosts of ARGs. The results showed that a total of 37 ARGs and 8 MGEs were detected in the study area. The detection rate of 9 ARGs (aac(6')-Ib(aka aacA4)-02, catA1, cmlA, cfr, sul1, sul2, sulA/folP-01, tetC, tetX) was 100 %. The absolute abundance of ARGs in the 12 sampling points ranged from 2.75 × 107 to 3.79 × 1010 copies·L-1, and the absolute abundance of MGEs was 1.30 × 105 to 2.54 × 107 copies·L-1, which was relatively high compared to other research areas. ARGs and MGEs were significantly correlated, indicating that MGEs play an important role as a mediator in the spread of ARGs. At the phylum level, Proteobacteria and Cyanobacteria were the dominant bacteria in the study area, with HIMB11 and unidentifiedChloroplast being the dominant levels, respectively. Network analysis of ARGs and microorganisms (genus level) revealed that Cognatishimia, Thalassobius, Aestuariicoccus, Thalassotalea, and Vibrio were significantly correlated with multiple ARGs and were the main potential hosts of ARGs in the nearshore waters of Wenchang.

Mechanistic toxicity and growth abnormalities mediated by subacute exposure to environmentally relevant levels of benzophenone-3 in clown anemonefish (Amphiprion ocellaris).

Benzophenone-3 (BP-3) is a UV filter that is ubiquitously present in the environment due to its photostability and degradation resistance and has wide applications in personal care products. BP-3 will eventually be discharged into the ocean. Studies shows BP-3 interferes with endocrine system of aquatic organisms, especially fish. However, the toxicity and mechanisms of subacute exposure of the coral reef fish to BP-3 remain elusive. Here, we exposed the one-month-old clown anemonefish to BP-3 at 1 and 10 µg/L for 14 and 28 days, respectively. After chronic exposure, the effects of BP-3 on the growth of clown anemonefish were investigated in terms of growth-related hormones, immune enzyme activity, digestive enzyme activity, transcriptional profiling of feeding- and obesity-related genes and digital RNA sequencing. The body weight in the BP-3 groups were abnormally increased (1 µg/L group in 14 days treatment and all groups in 28 days treatment), altered insulin content (28 days exposure), immune-related and digestive-related enzymatic activities. At the molecular level, BP-3 interferes with the expression of feeding- and obesity-related genes. Digital RNA sequencing analysis showed that BP-3 interferes with Kyoto encyclopedia of genes and genomes (KEGG) pathways related to growth, social behavior (learning behavior), Mitogen-Activated Protein Kinase (MAPK) signaling pathway, PI3K-Akt signaling pathway, and insulin secretion. Notably, in the insulin secretion, BP-3 induced Ca2+ up-regulation that may damage ß cells. Growth abnormalities and social behavior (learning behavior) KEGG pathway disturbances may have potential impacts on populations of clown anemonefish. Our results reveal the toxicological effects of subacute exposure to BP-3, and provides insight into the effects and mechanisms of BP-3 on clown anemonefish growth.

Phenylalanine-mediated changes in the soil bacterial community promote nitrogen cycling and plant growth.

Soil amino acids (AAs) are the most active components of soil N, which can be mineralized or absorbed by bacteria as N and C sources. We hypothesized that exogenous AAs could regulate the bacterial community and affect soil N cycling, and the effect sizes could vary depending on individual AAs. Here, we applied feather (keratin)-based compost rich in AAs to Poncirus trifoliata (L.) to evaluate the regulation of bacterial community by AAs; furthermore, we applied six individual AAs to test their effects. The compost significantly increased soil hydrolysable AA content, ammonia monooxygenase gene abundance, and plant growth and changed bacterial community structure. Redundancy analysis revealed that the effects of AAs on the bacterial community composition were greater than those of soil chemical properties, and phenylalanine (Phe) was the most effective among thirteen individual AAs. When applied individually, Phe caused the greatest increase in N cycling-related enzyme activity and plant growth and most significantly altered the bacterial community structure among the six exogenous AAs. Notably, Phe significantly increased the relative abundances of Burkholderia-Caballeronia-Paraburkholderia, Azospirillum, Cupriavidus, and Achromobacter, whose abundances were significantly positively correlated with plant biomass, and significantly reduced the relative abundances of Arachidicoccus, Pseudopedobacter, Sphingobacterium, and Paenibacillus, whose abundances were significantly negatively correlated with plant biomass. We demonstrate that soil AAs strongly shape the bacterial community. Particularly, Phe enhances N cycling and plant growth by increasing the potentially beneficial bacterial taxa and inhibiting the potentially harmful bacterial taxa, which needs further validation.

Occurrence and Distribution of Antibiotics in a Tropical Mariculture Area of Hainan, China: Implications for Risk Assessment and Management.

With the rapid global demand for mariculture products in recent years, the use of antibiotics has increased intensively in the mariculture area. Current research on antibiotic residues in mariculture environments is limited, and less information is available on the presence of antibiotics in tropical waters, limiting a comprehensive understanding of their environmental presence and risk. Therefore, this study investigated the environmental occurrence and distribution of 50 antibiotics in the near-shore aquaculture waters of Fengjia Bay. A total of 21 antibiotics were detected in 12 sampling sites, including 11 quinolones, 5 sulfonamides, 4 tetracyclines, and 1 chloramphenicol; the quinolones pyrimethamine (PIP), delafloxacin (DAN), flurofloxacin (FLE), ciprofloxacin (CIP), norfloxacin (NOR), pefloxacin (PEF), enrofloxacin (ENO), and minocycline (MNO) of the tetracycline class were detected in all sampling points. The total antibiotic residue concentrations in the study area ranged from 153.6 to 1550.8 ng/L, the tetracycline antibiotics were detected in the range of 10 to 1344.7 ng/L, and the chloramphenicol antibiotics were detected in the range of 0 to 106.9 ng/L. The detected concentrations of quinolones ranged from 81.3 to 136.1 ng/L, and the residual concentrations of sulfonamide antibiotics ranged from 0 to 313.7 ng/L. The correlation analysis with environmental factors revealed that pH, temperature, conductivity, salinity, NH3--N, and total phosphorus had a strong correlation with antibiotics. Based on PCA analysis, the main sources of antibiotic pollution in the area were determined to be the discharge of farming wastewater and domestic sewage. The ecological risk assessment indicated that the residual antibiotics in the water environment of the near-shore waters of Fengjiawan had certain risks to the ecosystem. Among them, CIP, NOR, sulfamethoxazole (TMP), ofloxacin (OFL), enrofloxacin (ENO), sulfamethoxazole (SMX), and FLE showed medium to high risk. Therefore, it is recommended to regulate the use of these antibiotics and the discharge and treatment of culturing wastewater, and measures should be taken to reduce the environmental pollution caused by antibiotics and to monitor the long-term ecological risk of antibiotics in the region. Overall, our results provide an important reference for understanding the distribution and ecological risk of antibiotics in Fengjiawan.

Cooperation of arbuscular mycorrhizal fungi and bacteria to facilitate the host plant growth dependent on soil pH.

Almost all plants grow well in their native soils. We hypothesized that soil microbes promote the growth of their hosts in native soils by the example of soil pH. Here, bahiagrass (Paspalum notatum Flugge) indigenous to subtropical soils was grown in the native soil (the original pH = 4.85) or in pH-adjusted soils with sulfur (pH = 3.14 or 3.34) or calcium hydroxide (pH = 6.85, 8.34, 8.52 or 8.59). Plant growth, soil chemical property, and microbial community composition were characterized to reveal the microbial taxa promoting plant growth in the native soil. Results showed that shoot biomass was the highest in the native soil, while both the decrease and increase in the soil pH reduced the biomass. Compared with other soil chemical properties, soil pH was the top edaphic factor contributing to the differentiation in arbuscular mycorrhizal (AM) fungal and bacterial communities. The top 3 most abundant AM fungal OTUs belonged to Glomus, Claroideoglomus, and Gigaspora, while the top 3 most abundant bacterial OTUs belonged to Clostridiales, Sphingomonas, and Acidothermus, respectively. Regression analyses between microbial abundances and shoot biomass revealed that the most abundant Gigaspora sp. and Sphingomonas sp. were the most promotive fungal and bacterial OTUs, respectively. The application of these two isolates to bahiagrass solely or in combination indicated that Gigaspora sp. was more promotive than Sphingomonas sp. across the soil pH gradient, and they positively interacted to enhance biomass only in the native soil. We demonstrate that microbes cooperate to facilitate host plants to grow well in their native soils with the original pH. Meanwhile, a high-throughput sequencing-guided pipeline to efficiently screen for beneficial microbes is established.

A synthetic community of siderophore-producing bacteria increases soil selenium bioavailability and plant uptake through regulation of the soil microbiome.

Dietary selenium (Se) is an effective strategy to meet Se requirement of human body, and Se biofortification in crops in seleniferous soils with selenobacteria represents an eco-friendly biotechnique. In this study, we tested the effectiveness of siderophore-producing bacterial (SPB) synthetic communities (SynComs) in promoting plant Se uptake in a subtropical seleniferous soil where the fixation of Se by ferric-oxides is severe. The results indicated that SPB SynComs drastically elevated soil bioavailable Se content by up to 68.7 %, and significantly increased plant Se concentration and uptake by up to 83.1 % and 92.2 %, respectively. Seven out of ten SPB isolates in the SynComs were enriched in soils after 120 days of inoculation. Additionally, variation partitioning analysis (VPA) revealed that the contribution of soil bacterial community (up to 42.8 %) to the increased plant Se uptake was much greater than that of soil bioavailable Se (up to 5.1 %), suggesting a direct pathway other than the pathway of mobilizing Se. The relative abundances of some operational taxonomic units (OTUs) showed significantly positive relationship with plant Se status but not with soil Se status, which supports the results of VPA. Network analysis indicates that some inoculated SPB isolates promoted plant Se uptake by regulating the native bacterial taxa. Taken together, this study demonstrates that SPB can be used in Se biofortification in crops, especially in subtropical soils.

Environmental concentrations of benzophenone-3 disturbed lipid metabolism in the liver of clown anemonefish (Amphiprion ocellaris).

Benzophenone-3 (BP-3) often used as a UV filter in various products and an endocrine disruptor. In this work, we exposed the clown anemonefish to 10 µg/L and 50 µg/L BP-3 for 7 and 14 days. Liver histological, biochemical analysis, and transcriptome sequencing were used to explore the mechanism of the lipid metabolism disorder in the liver of three-month-old clown anemonefish treated with BP-3. The histological and biochemical analysis showed that BP-3 induces morphological changes and lipid droplet accumulation, and the lipid content, lipase, and antioxidant enzyme activity were abnormal. After treatment with 10 µg/L and 50 µg/L BP-3 for 7 days, the transcriptome analysis further demonstrated that the KEGG analysis revealed that the differentially expressed genes (DEGs) were mainly associated with fat digestion and absorption, PPAR signaling pathway, circadian rhythm, and mineral absorption pathways; After 10 µg/L and 50 µg/L of BP-3 exposure for 14 days, the KEGG analysis were mainly associated with circadian rhythm, circadian rhythm-fly, protein processing in the endoplasmic reticulum, and beta-alanine metabolism pathways. Several key genes were involved in the process of liver lipid metabolism, including CD36, APoA-Ⅰ, FABP, LPL, ACS, and PEPCK. The qRT-PCR validation results showed that eight genes (CYP8B1, FABP1, LPL, MGAT, PEPCK, PER1, PSMB4, PSME2) were significantly down-regulated, and the other two genes (Fbxl3, RXR) were significantly up-regulated after 7 days of BP-3 exposure. Similarly, eleven genes (AMPK, ARNTL, Bmal1, CASP3, CYC, CYP2J, CYP2U1, GSK3A, PEPCK, RAC1, RORA) were significantly up-regulated, and the other four genes (NR1D1, PER1, PTGDS, HLF) were significantly down-regulated after 14 days of BP-3 exposure. In conclusion, our results elucidate the physiological and molecular responses to BP-3 exposure in the liver lipid metabolism of clown anemonefish, and these findings reveal that the regulation of lipid metabolism is disturbed when clown anemonefish is exposed to UV filters.

Microbial Diversity Characteristics of Areca Palm Rhizosphere Soil at Different Growth Stages.

The rhizosphere microflora are key determinants that contribute to plant health and productivity, which can support plant nutrition and resistance to biotic and abiotic stressors. However, limited research is conducted on the areca palm rhizosphere microbiota. To further study the effect of the areca palm's developmental stages on the rhizosphere microbiota, the rhizosphere microbiota of areca palm (Areca catechu) grown in its main producing area were examined in Wanning, Hainan province, at different vegetation stages by an Illumina Miseq sequence analysis of the 16S ribosomal ribonucleic acid and internal transcribed spacer genes. Significant shifts of the taxonomic composition of the bacteria and fungi were observed in the four stages. Burkholderia-Caballeronia-Paraburkholderia were the most dominant group in stage T1 and T2; the genera Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium were decreased significantly from T1 to T2; and the genera Acidothermus and Bacillus were the most dominant in stage T3 and T4, respectively. Meanwhile, Neocosmospora, Saitozyma, Penicillium, and Trichoderma were the most dominant genera in the stage T1, T2, T3, and T4, respectively. Among the core microbiota, the dominant bacterial genera were Burkholderia-Caballeronia-Paraburkholderia and Bacillus, and the dominant fungal genera were Saitozyma and Trichoderma. In addition, we identified five bacterial genera and five fungal genera that reached significant levels during development. Finally, we constructed the OTU (top 30) interaction network of bacteria and fungi, revealed its interaction characteristics, and found that the bacterial OTUs exhibited more extensive interactions than the fungal OTUs. Understanding the rhizosphere soil microbial diversity characteristics of the areca palm could provide the basis for exploring microbial association and maintaining the areca palm's health.

Directly Exfoliated Ultrathin Silicon Nanosheets for Enhanced Photocatalytic Hydrogen Production.

Here we present direct exfoliation of ultrathin silicon nanosheets from commercial silicon powders through an improved liquid phase exfoliation procedure. The feasibility of exfoliation was ascribed to the intrinsic anisotropic lattice structure, which allowed the oriented propagations of cryo-mediation-induced quenching cracks with the assistance of sonication. It was also revealed that the solid-solvent interface played a critical role in determining the morphology of exfoliated pieces as well as the exfoliation efficiency. Moreover, due to its superior morphology, enlarged surface area, and improved photon absorption, the resulting ultrathin silicon nanosheets presented enhanced and visible light responsive photocatalytic hydrogen generation performance, even without applying any co-catalyst.

Rational Design of Oxygen Deficiency-Controlled Tungsten Oxide Electrochromic Films with an Exceptional Memory Effect.

Owing to their nonemissive characteristics, electrochromic materials promise distinct advantages in developing next-generation eye-friendly information displays. Yet, it remains a challenge to manipulate the structure of the materials to achieve a strong memory effect with high optical contrast, which is of importance for displaying images with essentially zero energy consumption. Here, we design a mixed crystalline WOx thin film implanted with massive oxygen deficiencies based on a conventional reactive magnetron sputtering process. The obtained WOx film exhibits high dual-band optical modulation in both visible (VIS, 99.0% in 633 nm) and near-infrared (NIR, 94.2% in 1300 nm) regions as well as an exceptional memory effect (the colored transmittance increases only by 0.04% at 633 nm after 50 days). The enhanced electrochromic performance can be attributed to dense Li+-ion binding sites as well as the trapping effect provided by the massive internal oxygen deficiencies. The strategy in this work bestows the WOx thin film a promising candidate for developing electrochromic information displays and other energy-efficient devices as well.

A solvent-assisted ligand exchange approach enables metal-organic frameworks with diverse and complex architectures.

Unlike inorganic crystals, metal-organic frameworks do not have a well-developed nanostructure library, and establishing their appropriately diverse and complex architectures remains a major challenge. Here, we demonstrate a general route to control metal-organic framework structure by a solvent-assisted ligand exchange approach. Thirteen different types of metal-organic framework structures have been prepared successfully. To demonstrate a proof of concept application, we used the obtained metal-organic framework materials as precursors for synthesizing nanoporous carbons and investigated their electrochemical Na+ storage properties. Due to the unique architecture, the one-dimensional nanoporous carbon derived from double-shelled ZnCo bimetallic zeolitic imidazolate framework nanotubes exhibits high specific capacity as well as superior rate capability and cycling stability. Our study offers an avenue for the controllable preparation of well-designed meta-organic framework structures and their derivatives, which would further broaden the application opportunities of metal-organic framework materials.

MoS2 quantum dots decorated ultrathin NiO nanosheets for overall water splitting.

Atomically thin 2D materials with high surface areas allow engineering its physical and chemical properties with help of combining or decorating with different classes of materials. The hybrid or heterostructure of two different atomically thin materials exhibits completely different chemical and electronics behavior as compared to its parent components. Here, MoS2 quantum dots (QDs) are decorated onto ultrathin NiO nanosheets (NSs) by using a one-pot hydrothermal process. Uniformly dispersed MoS2 QDs and ultrathin NiO NSs hybrid/heterostructure can provide more active reaction sites and accelerate the charge transfer rate. Benefiting from the heterointerfaces synergistic effect between MoS2 QDs and NiO NSs, the MoS2 QDs/NiO NSs electrode exhibits excellent electrocatalytic activity towards both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As a bifunctional electrocatalyst, the MoS2 QDs/NiO NSs electrode has achieved highly efficient overall water splitting activity, which needs a low voltage of 1.61 V to deliver a 10 mA cm-2 with superior stability.

Synthesis of SrTiO3 submicron cubes with simultaneous and competitive photocatalytic activity for H2O splitting and CO2 reduction.

Single crystalline strontium titanate (SrTiO3) submicron cubes have been synthesized based on a molten salt method. The submicron cubes showed superior photocatalytic activity towards both water splitting and carbon dioxide reduction, in which methane (CH4) and hydrogen (H2) were simultaneously produced. The average production rate of methane up to 8 h is 4.39 µmol g-1 h-1 but drops to 0.46 µmol g-1 h-1. However, the average production rate of hydrogen is 14.52 before 8 h but then increases to 120.23 µmol g-1 h-1 after 8 h. The rate change of the two processes confirms the competition between the H2O splitting and CO2 reduction reactions. Band structure and surface characteristics of the SrTiO3 submicron cubes were characterized by diffuse reflective UV-Vis spectroscopy, Mott-Schottky analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results reveal that the simultaneous and competitive production of methane and hydrogen is due to a thermodynamics factor, as well as the competition between the adsorption of carbon dioxide and water molecules on the surface of the faceted SrTiO3. This work demonstrates that SrTiO3 photocatalysts are efficient in producing sustainable fuels via water splitting and carbon dioxide reduction reactions.

Broadband Plasmonic Enhancement of High-Efficiency Dye-Sensitized Solar Cells by Incorporating Au@Ag@SiO2 Core-Shell Nanocuboids.

The introduction of plasmonic additives is a promising approach to boost the efficiency of the dye-sensitized solar cell (DSSC) since they may improve the light harvesting of a solar cell. Herein, we design broadband and strong plasmonic absorption Au@Ag@SiO2 nanocuboids (GSS NCs) as nanophotonic inclusions to achieve plasmon-enhanced DSSCs. These multiple-resonance absorptions arising from GSS NCs can be readily adjusted by altering their structures to complementarily match the absorption spectra of the dyes, especially in weak absorption zones. By subtly regulating the position of nanophotonic inclusions in the photoanodes, not only the plasmonic near-field enhancement but also far-field light scattering could be adequately developed to promote the light harvest and thus the efficiency of DSSCs. The resulting solar cells yield an average efficiency of 10.34%, with a champion value of 10.58%. The electromagnetic simulations are consistent with the experimental observations, further corroborating the synergistic effect of plasmonic improvement in these DSSCs.

3D carbon coated NiCo2S4 nanowires doped with nitrogen for electrochemical energy storage and conversion.

Three-dimensional (3D) carbon-coated NiCo2S4 nanowires structures doped with nitrogen are used for energy storage and conversions. The nitrogen doping in both the carbon layer and NiCo2S4 nanowires enhances the electrochemical performances. Here, an easily scalable and simple temperature treatment has been used to decorate carbon-coated NiCo2S4 nanowires with nitrogen doping (NC@NiCo2S4 NWs) in 3D carbon architecture (carbon cloth). Benefiting from the nitrogen doping and ultrathin carbon layer, the as-prepared 3D NC@NiCo2S4 NWs electrode exhibits the superior electrochemical performance for both asymmetric supercapacitor and electrocatalytic water splitting. An asymmetric supercapacitor assembled by the NC@NiCo2S4 NWs and active carbon electrodes achieves a high energy density of 1.72 mWh cm-3 (68.87 Wh kg-1) under a power density of 10.63 mW cm-3 (425 W kg-1) with 90.1% retention of initial capacitance after 10,000 cycles. When employed as the electrocatalyst, the NC@NiCo2S4 NWs show high activities towards electrocatalytic water splitting.

Water-Soluble Defect-Rich MoS2 Ultrathin Nanosheets for Enhanced Hydrogen Evolution.

In this work, we report a facile cryo-mediated liquid phase exfoliation method to synthesize water-soluble defect-rich MoS2 ultrathin nanosheets (d-MoS2 NSs) with the assistance of NaBH4 in the solvent. The as-prepared d-MoS2 NSs show enhanced electrocatalytic hydrogen evolution reaction (HER) performance in comparison to that of MoS2 NSs due to surface hydrophilicity and abundant active edge sites. The formation process of the d-MoS2 NSs with exposed edge sites is illustrated by investigating the influence of exfoliation time on their structural morphology. The optimal water-soluble d-MoS2 NSs display excellent HER activities, including a low overpotential of 71.5 mV at a current density of -10 mA cm-2, a small Tafel slope of 58.3 mV dec-1, and good cycling stability.

Soil Bacterial Function Associated With Stylo (Legume) and Bahiagrass (Grass) Is Affected More Strongly by Soil Chemical Property Than by Bacterial Community Composition.

Soil microbes are driver of nutrient cycling, with microbial function affected by community composition and soil chemical property. Legume and grass are ubiquitous in many ecosystems, however, their differential effects on microbial function are less understood. Here we constructed compartmented rhizobox planted with stylo (Stylosanthes guianensis, legume) or bahiagrass (Paspalum natatum, grass) to compare their influences on bacterial function and to investigate the determinant of bacterial function. Soils in root compartment and in near (0-5 mm from root compartment) or far (10-15 mm from root compartment) rhizosphere were sampled. Soil chemical properties, bacterial community composition and function were characterized. Results indicate that plant species and distance significantly affected bacterial function. The activities of beta-xylosidase, nitrate reductase and phosphomonoesterase were higher in stylo soil than in bahiagrass soil, while leucine-aminopeptidase activity and nosZ abundance were vice versa. Rhizosphere effect was obvious for the activities of beta-glucosidase, beta-xylosidase, chitinase, and the abundances of AOB-amoA, nirS, nosZ. Statistical analysis revealed that soil chemical property was significantly associated with bacterial function, with a higher coefficient than bacterial community composition. These data suggest that stylo and bahiagrass differentially affect bacterial function, which is affected more strongly by soil chemical property than by community composition.

3D Coral-Like Ni3S2 on Ni Foam as a Bifunctional Electrocatalyst for Overall Water Splitting.

High-performance noble metal-free electrocatalysts are extremely desired for overall water splitting, but there are huge challenges. Herein, we report a novel one-step electrochemical anodic oxidation and cathodic deposition strategy to in situ fabricate three-dimensional coral-like Ni3S2 on Ni foam (NF) for electrocatalytic overall water splitting. In a typical two-electrode cell, NF acts as both cathodic and anodic electrodes with thiourea aqueous solution as the electrolyte. The nickel ions from the anodic oxidation of NF are directly used as nickel sources to form 3D coral-like Ni3S2/NF by the cathodic deposition method simultaneously. The optimal 3D Ni3S2/NF-4 electrode shows high electrocatalytic activity for hydrogen evolution reaction and oxygen evolution reaction with low overpotentials of 89 and 242 mV, respectively, to afford 10 mA cm-2. When the as-obtained Ni3S2/NF-4 is used as a bifunctional electrocatalyst in an electrolyzer, a low applied voltage of 1.577 V is needed to reach 10 mA cm-2, with extremely long durability. This work focuses on the rational design of unique structures as efficient non-noble metal-based electrocatalysts, which hold great potential for practical applications in electrocatalytic water splitting.