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Abstract We report an innovative strategy to prepare the porous N-doped graphene aerogel with an open structure and abundant defects by hydrothermal self-assembly of zeolitic imidazolate framework (ZIF)-8 and graphene oxide. The in-situ hydrothermal restructuring of ZIF-8 on graphene sheets plays a key role in the synthesis of the open structure and the uniform N-doping. The dissolution and restructuring of ZIF-8 on graphene oxide obviously suppress the stacking and reunion of graphene sheets to obtain the continuous macroporous structure. Moreover, the introduction of N and Zn creates the abundant N-doped sites and microporous structure. Its unique structure and composition improve the accessible surface area, the mass transfer diffusion, the dispersion and electronic structure of Pt nanoparticles, further resulting in the high catalytic performance of Pt-based catalyst for methanol oxidation reaction (MOR). Its MOR activity is about 1.8 times of commercial Pt/C, and its long cycling durability is improved by about 18.7% compared with commercial Pt/C. This work renders a promising method by utilizing ZIF-8 derivatives to synthesize the excellent N-doped carbon materials for electrochemical applications. Graphical abstract This is the first time to utilize the in-situ hydrothermal restructuring of ZIF-8 to synthesize the N-doped graphene aerogel with a more open structure as excellent Pt catalyst support for methanol electro-oxidation. Image 1 Highlights • In-situ hydrothermal restructuring of ZIF-8 is utilized to prepare the N-doped graphene aerogel. • The as-prepared support possesses a very open structure constructed and abundant defects. • The unique structure improves the accessible surface area, mass transfer diffusion, the Pt dispersion. • Compared with Pt/C, the catalytic activity and durability of methanol oxidation has been increased. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) hybrid aerogels built from graphene and polypyrrole-derived nitrogen-doped carbon nanotubes (G-NCNTs) are synthesized by facile hydrothermal and heat treatment process using graphite oxide (GO) and polypyrrole nanotubes (PNTs) as precursors. The 3D G-NCNTs hybrid aerogels, in which the NCNTs are dispersed homogeneously in the graphene sheets, are designed to efficiently support Pt nanoparticles. Comparing with 3D graphene (GA), the 3D G-NCNTs supported Pt-based catalyst possesses improved electrocatalysis activity and stability toward methanol oxidation reaction (MOR). The mass activity of Pt/G-NCNTs-1/2 catalyst is 0.74 A mg −1 Pt , which is 1.4 times that of the Pt/GA catalyst (0.54 A mg −1 Pt ). In addition, the retention rate after 1000 cycles for Pt/G-NCNTs-1/2 catalyst is as high as 82.4%, obviously superior to 68.5% of Pt/GA catalyst. The enhanced electrochemical performance is ascribed to the synergistic effect of GA and NCNTs. The introduction of NCNTs can uniformly disperse and strongly anchor Pt nanoparticles due to the increase in nitrogen active sites. Moreover, the NCNTs introduced into GA may prevent the restacking of graphene sheets, and provide a large accessible surface area for better dispersing Pt nanoparticles and transporting reactants and products. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanotubes (CN x -NTs), platinum (Pt)-based catalysts supports, were prepared by pyrolysis of polypyrrole nanotubes (PPy-NTs), which were synthesized using a self-degraded template method. The morphology, structure and physicochemical properties of CN x -NTs supports and Pt/CN x -NTs catalysts were investigated by scanning electron microscope, Brunauer-Emmett-Teller surface area, transmission electron microscopy, X-ray diffraction, and X-Ray photoelectron spectroscopy. Fine Pt nanoparticles are uniformly deposited onto the CN x -NTs supports, which possess well-defined nanotube morphology. The Pt/CN x -NTs catalysts, especially Pt/CN x -NTs-800 catalyst (CN x -NTs prepared at pyrolysis temperature of 800 °C), exhibit outstanding electrochemical performance toward methanol oxidation reaction (MOR), compared with commercial Pt/C catalyst, which is attributed to high nitrogen content and nanotube morphology of the support. High nitrogen content can better disperse and anchor Pt nanoparticles, and nanotube structure may provide an open network around the active catalysts for facilitating the mass transfer. Under the same electrocatalytic activity, the Pt loading of the Pt/CN x -NTs-800 catalyst is reduced by 56.3% comparing with commercial Pt/C catalyst. The results indicate that the CN x -NTs-800 as support greatly reduces the loading of noble metal platinum, further promoting the commercialization process of proton exchange membrane fuel cells (PEMFCs). [ABSTRACT FROM AUTHOR]

The NO adsorption and dissociation on neutral, charged and Ni-doped Pd 13 clusters were studied by using density functional calculations. Our results revealed that NO always prefers to adsorb on the hollow site rather than the top or bridge sites. However, the charge state and Ni doping remarkably influence NO adsorption energy, dissociation barrier and reaction energy. The reaction on Pd 13 − has the lowest energy barrier and largest reaction energy. The Hirshfeld charge analysis discloses that the origin of the catalytic activity difference is the charge transfer from clusters to NO in the metastable NO adsorption state. [ABSTRACT FROM AUTHOR]

A novel nitrogen-doped carbon material with honeycomb-like mesoporous structure was synthesized via carbonization of polyaniline under template and acted as support for the Pt catalyst. Pyrolysis temperature plays a significant role in enhancing electrochemical performance of Pt/mesoporous nitrogen-doped carbon (Pt/MNC) catalyst. Considering comprehensively electrocatalytic activity and stability for methanol electrooxidation, MNC-900 (MNC prepared at pyrolysis temperature of 900 °C) is an appropriate support for Pt catalyst. Moreover, the electrochemical performance of Pt/MNC-900 catalyst is significantly superior to that of Pt/mesoporous carbon (Pt/MC) catalyst. The enhancement is attributed to N species introduced to the support and optimal proportion of pyridinic N, pyrrolic N and graphitic N. When the contents of pyridinic N, pyrrolic N and graphitic N achieve optimal proportion, MNC support reveals not only intense anchoring effect of Pt nanoparticles but also enhanced electric conductivity, further improving electrocatalytic activity and stability of the catalyst. [ABSTRACT FROM AUTHOR]

In this study, a series of 1,8-naphthalimide-based analogs were developed for fluorescence imaging of nucleotides in Caenorhabditis elegans . In DMSO, compound 1 proved to be an effective and selective colorimetric and fluorescent sensor for recognition of GMP, TMP, and UMP over other structurally similar nucleotides. Among all the tested nucleotides, only the addition of GMP, TMP, and UMP resulted in a fluorescence color change from blue to brown with a fluorescence enhancement of more than 600-fold, with the colorless solution turning brown. NMR spectroscopic titration, theoretical calculations, and spectral tests performed using various solvent compositions confirmed that compound 1 formed multiple hydrogen bonds with the related base groups in the nucleotide. Compound 1 demonstrated its utility as a fluorescent chemosensor for detecting GMP, TMP, and UMP in in vivo imaging of GMP, TMP, and UMP in C. elegans . [ABSTRACT FROM AUTHOR]

Abstract: Euryarchaeota, as an important and ubiquitous Archaea phylum, contributes substantially to global energy cycling. However, there is a considerable lack of knowledge regarding their biogeographic patterns in terrestrial ecosystems. Here barcoded pyrosequencing was employed to compare the relative abundance, diversity and community composition of Euryarchaeota in 92 soil samples, collected from a variety of ecosystem types. A total of 96,534 euryarchaeal sequences were classified from pyrosequencing of the archaeal 16S rRNA gene, comprising 22.5% of the total archaeal sequences detected. Paddy soils harbored contrasting Euryarchaeota communities from upland soils (including cropland, grassland, forest, and tea orchard soil), at all taxonomic resolutions from phylum to genus level. Within upland soils, the relative abundance of Euryarchaeota in Archaea, and Euryarchaeota operational taxonomic unit (OTU) richness are significantly influenced by soil pH and H2O%. Similar observations held true for the beta diversity patterns, with soil pH and H2O% best explaining the variance of the pairwise Bray–Curtis dissimilarity. By comparison, within paddy soils, the Euryarchaeota abundance in Archaea, and the alpha and beta diversity patterns, could be best predicted along the gradients of soil pH and NH4 +-N. These findings were further corroborated by the evident pH-, H2O%- or NH4 +-N-associated distributions of several major Euryarchaeota orders. Taken together, our results emphasized the significant importance of soil pH as the prevailing environmental factor in shaping the terrestrial Euryarchaeota. [Copyright &y& Elsevier]

Abstract: Soil bacterial communities mediate a wide range of ecosystem processes. In agricultural systems these processes determine soil health through bacterial roles in residue decomposition, nutrient cycling and their associations with other organisms. In this study, we investigated the abundance and composition of native soil bacterial communities under different long-term fertilization practices using quantitative real-time polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE). Soil samples were taken from a 20-year fertilization trial at the Plastic-film Mulching Experiment Station in Northeast China, which including four treatments of control (CK), inorganic-N fertilizer amendment (N), organic manure amendment (M), and half fertilizer-N plus half organic manure (M+N), to identify the difference of soil bacterial community under inorganic fertilizer and manure amendment. The size of the general bacterial population in the N treatment was significantly smaller than those in the CK, M and M+N treatments. Soil bacterial 16S rRNA gene copy numbers were positively correlated with soil pH and total organic carbon (TOC) content. The DGGE band patterns in CK, M and M+N treatments demonstrated more similarly to each other than to those of soil with only N amendment, while canonical correspondence analysis (CCA) revealed that the bacterial community structure in the N treatment was significantly different from the treatments of CK and M bacterial community profiles. Phylogenetic analysis of bands excised from the DGGE gels identified seven major phyla (Acidobacteria, Bacteroidetes, Gemmatimonadetes, Proteobacteria, Actinobacteria, Gammaproteobacteria and Firmicutes) present in all the treatments except the N treatment, in which no Gammaproteobacteria was observed. Results from this study suggest that agricultural fertilization practices have a great impact on soil bacterial community size and structure. [ABSTRACT FROM AUTHOR]

Biogenic Mn oxides exert important controls on trace metal cycling in aquatic and soil environments. A Mn-oxidizing bacterium Bacillus sp. WH4 was isolated from Fe¿Mn nodules of an agrudalf in central China. The biogenic Mn oxides formed by mediation of this Mn oxidizing microorganism were identified as short-ranged and nano-sized Mn oxides. Cd adsorption isotherms, pH effect on adsorption and kinetics were investigated in comparison with an abiotic Mn oxide todorokite. Maximum adsorption of Cd to the biogenic Mn oxides and todorokite was 2.04 and 0.69mmol g¿1 sorbent, respectively. Thus, the biogenic Mn oxides were more effective Cd adsorbents than the abiotic Mn oxide in the aquatic environment. The findings could improve our knowledge of biogenic Mn oxides formation in the environment and their important roles in the biogeochemical cycles of heavy metals. [Copyright &y& Elsevier]

Abstract: Flooded rice paddy soils represent a typical anaerobic freshwater habitat of microorganisms. The abundance and community structure of sulfate reducing prokaryotes (SRP) were investigated in order to understand their response to different fertilization practices in rice paddy, including control without fertilizers (CT) and arrangements of different chemical fertilizers of nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK and NPK. The abundance of total bacteria and sulfate reducing prokaryotes of the rice paddy in summer and in winter were quantified by real-time PCR assays based on the 16S rRNA gene and the dissimilatory (bi)sulfite reductase gene (dsrAB) β-subunit. No significant differences in the bacterial and SRP abundance were observed among different fertilization treatments in both winter and summer. The mean copy numbers of bacteria was 7.26×109 copies g−1 dry soil in winter and 1.27×1010 copies g−1 dry soil in summer. The average dsrAB gene copy numbers of the SRP was 5.08×108 copies g−1 dry soil in winter and 5.92×108 copies g−1 dry soil in summer. The dsrAB gene clone libraries of the five fertilization treatments were constructed and their RFLP analysis yielded 22–25 restriction patterns, suggesting a high degree of dsrAB sequence diversity in different fertilization treatments. There was no significant change in the soil SRP community structure among the different fertilization regimes. More than half of the sequences were affiliated with novel branching clusters which were uncultured SRP. Clostridia and Deltaproteobacteria were also found with a high proportion in the clone libraries, while Desulfovibrionaceae was absent. High proportion of novel uncultured SRP implies that they may play important roles in paddy soils and deserve further studies. [Copyright &y& Elsevier]

Abstract: Iron–manganese (Fe–Mn) nodules and concretions are soil new growth, reflecting soil environmental conditions during their formation. Bacteria play a dominant role in the oxidation of dissolved Mn(II) in aqueous systems and the formation of marine and freshwater Fe–Mn nodules. However, the role and significance of bacteria in soil Fe–Mn nodule formation have not been well recognized. In this paper, microbial DNA was directly extracted from two Fe–Mn nodule samples collected from Wuhan and Guiyang in central China. The extracted DNA was amplified by polymerase chain reaction (PCR) and cloned. The clones were then screened by amplified ribosomal DNA restriction analysis (ARDRA). Twenty patterns were obtained for Wuhan sample and Guiyang sample, respectively. DNA sequencing and phylogenetic analyses revealed that the bacterial compositions of the Fe–Mn nodules were mainly belonged to Firmicutes, β-proteobacteria, γ-proteobacteria branches of the domain bacteria. These divisions had close relativeness with Mn(II)-oxidizing bacteria identified from marine Fe–Mn nodules, implying the possible contributions of these bacteria to soil Fe–Mn nodule formation. [Copyright &y& Elsevier]

• Explore the sum uncertainty relations for observables based on skew information. • Explore the sum uncertainty relations for quantum channels based on skew information. • Present some new uncertainty relations for observables and quantum channels. • Our uncertainty relations have much tighter lower bounds than the existing ones. • Detailed examples are provided. Uncertainty principle is the basis of quantum mechanics. It reflects the basic law of the movement of microscopic particles. Wigner-Yanase skew information, as a measure of quantum uncertainties, is used to characterize the intrinsic features of the state and the observable. In this paper, we mainly investigate the sum uncertainty relations for both quantum mechanical observables and quantum channels based on skew information. We establish a new uncertainty relation in terms of skew information for n observables, which is saturated (thus it holds as equality) for two incompatible observables. We also present two uncertainty relations for arbitrary finite N quantum channels by using skew information. Our uncertainty relations have tighter lower bounds than the existing ones. Detailed examples are provided. [ABSTRACT FROM AUTHOR]

Abstract: Recent studies of ammonia-oxidizing archaea (AOA) suggested their significant contributions to global nitrogen cycling, and phylogenetic analysis categorized AOA into a novel archaeal phylum, the Thaumarchaeota. AOA are ubiquitous in terrestrial ecosystems, have unique mechanisms for nitrification, better adaptation to low-pH pressures, and strikingly lower ammonia requirements compared with ammonia-oxidizing bacteria (AOB). Previous perceptions that microbial ammonia oxidation in acidic soils was minimal, and entirely meditated by autotrophic bacteria and occasionally by heterotrophic nitrifiers have been dramatically challenged, and the dominant nitrifying groups urgently called for re-assessment. Controversially, the relative contributions of AOA and AOB to autotrophic ammonia oxidation have been reported to vary in different soils, but ammonia substrate availability, which was largely restricted under acidic conditions, seemed to be the key driver. Theoretically predicted ammonia concentrations in acidic soils below the substrate threshold of AOB and remarkably high ammonia affinity of AOA raised the supposition that thaumarchaea could represent the dominant ammonia-oxidizing group in ammonia-limited acidic environments. Recently, the functional dominance of thaumarchaea over its bacterial counterpart and autotrophic thaumarchaeal ammonia oxidation in acidic soils has been compellingly confirmed by DNA-stable isotope probing (SIP) experiments and the cultivation of an obligate acidophilic thaumarchaeon, Nitrosotalea devanaterra. Here, we review the currently available knowledge concerning the history and progress in our understanding of the ammonia-oxidizing microorganisms (AOB and AOA) and the mechanisms of nitrification in nutrient-depleted acidic soils, present the possible mechanisms shaping the distinct niches of AOA and AOB, and thus strengthen the assumption that AOA dominate over AOB in ammonia oxidation of acidic soils. [Copyright &y& Elsevier]

Methanotrophs play a crucial role in mitigating methane (CH 4) emission by oxidizing produced CH 4 in paddy soils; however, ecological drivers of methanotrophic community in the soils around heavy metal contaminated areas remain unclear. In this study, we evaluated the effects of heavy metal pollution and soil properties on the abundance, diversity and composition of methanotrophic community in paddy soils from two typical mercury (Hg) mining regions in southwest China. The results of random forest and structure equation models suggest that both heavy metal content and soil nutrients greatly influenced the attributes of methanotrophic community. In general, the abundance and diversity of methanotrophs were negatively related to soil Hg content, but showed positive correlation with soil organic carbon content. However, the other metals (cadmium (Cd), nickel (Ni), lead (Pb), arsenic (As), zinc (Zn)) had inconsistent associations with the microbial indexes of methanotrophic community in the soil. Elevated levels of heavy metal and nutrients in the soils shifted the community composition of methanotrophs. For example, Pb, As and Zn contents had negative associations with the relative abundance of Methylocaldum. In addition, changes in the relative abundance of ecological clusters within the co-occurrence network of methanotrophs were related to metal contents and soil properties. Together, our findings provide novel insights into understanding ecological drivers of methanotrophic community in paddy soils around Hg mining regions, with important implications for mitigating CH 4 emissions in terrestrial ecosystems. Unlabelled Image • Metal contents and soil properties affected attributes of methanotrophic community. • Soil Hg content adversely affected the abundance and diversity of methanotrophs. • Soil organic C positively affected the abundance and diversity of methanotrophs. [ABSTRACT FROM AUTHOR]

Global changes in nitrogen (N) deposition, precipitation patterns and land use could have an impact on the biogeochemical N cycle mediated by microorganisms. Microbial responses to global changes have been generally evaluated in short-term studies, while the long-term effects are not well understood. In this study, the interactive effects of multiple global change factors on N-cycling microorganisms and their interactions with plants were investigated in a 9-year field experiment with N addition, watering and mowing in a temperate steppe in northern China. Quantitative PCR, terminal restriction fragment length polymorphism (T-RFLP) and clone library were used to analyze the abundance and community structure of ammonia oxidizers and denitrifiers, respectively. Bacterial 16S rRNA gene abundance significantly increased under mowing, but the functional gene abundances including amoA , nirS , nirK and nosZ genes were not affected. Watering significantly affected the ammonia-oxidizing archaea (AOA) community and N addition showed a strong effect on soil ammonia-oxidizing bacteria (AOB) and nosZ -containing denitrifier community structure. No significant interactive effects of mowing, N addition and watering on communities of soil ammonia oxidizers and denitrifiers were observed. Structure equation models suggested that plant biomass and community were significantly correlated with microbial communities and activities. These findings suggest that there are complex interactions between plants and soil microorganisms in grassland ecosystems. [ABSTRACT FROM AUTHOR]

During the past decades, extensive nitrogen fertilization and acid deposition have greatly contributed to soil acidification in agroecosystems. Liming, the addition of calcium- and magnesium-rich material to soil, is an effective management strategy used to improve fertility and productivity of agricultural soils degraded by acidification. Nitrification plays a central role in nitrogen (N) availability in agroecosystems and contributes to soil acidification. However, little is known regarding the effects of liming on this process and microbial populations that drive it. Here, we investigated population dynamics and activity of ammonia oxidizers in response to a 2-year liming field trial in acidic soils received long-term fertilization with chemical N fertilizers and short-term lime amendment in microcosm incubations. Our results showed that activity, abundance and population structure of both ammonia-oxidizing archaea (AOA) and bacteria (AOB) were sensitive to liming in fertilized acidic soils. AOB abundance and potential nitrification rates increased in field plots subjected to liming, whereas the opposite was observed for AOA. In microcosm incubations, AOA abundance increased progressively over 60 days, namely under low CaO levels, whereas AOB abundance was greatly stimulated only during the first week under high CaO levels. 13 CO 2 -SIP-DNA experiments further supported that AOA were the most active ammonia oxidizers in fertilized field soils. However, in N-fertilized soils freshly amended with CaO, only autotrophic growth of AOB was observed after seven days, but not after 30 days when growth of AOA was observed. Taken together, our results indicated that both AOA and AOB play a role in nitrification following liming in fertilized acidic soils, likely through selection of better adapted clades of organisms. Although AOA were likely the main drivers of nitrification in these soils in the long-term, liming stimulated AOB activity in the short-term. [ABSTRACT FROM AUTHOR]

Molybdenum trioxide (MoO 3 ) has been considered an advanced auxiliary support for Pt nanoparticle anchorage due to its excellent activity and stability. Nevertheless, its non-conductivity property still impedes its applications in electrocatalytic fields. Thus, the MoO 3 and carbon composite of a nanostructure is synthesized through sintering process and served as an efficient co-support for Pt-based anode catalyst in this paper. The electrochemical measurements demonstrate that Pt/MoO 3 -C catalyst shows higher catalytic activity and stability than the as-prepared Pt/C. Significantly, it exhibits 1.95 times higher activity and 2.36 times better durability for methanol oxidation when compared with commercial Pt/C. The remarkably enhanced performance of this novel Pt/MoO 3 -C catalyst for methanol electrooxidation can be ascribed to the abundant Pt nucleation active sites, uniformly dispersed Pt nanoparticles and the strong metal-support interaction between Pt and MoO 3 -C. These outstanding properties suggest Pt/MoO 3 -C a promising catalyst for practical application of fuel cell. [ABSTRACT FROM AUTHOR]

Carbon black (CB), multiwalled carbon nanotubes (MWNTs), reduced graphene oxide (rGO) are used as the cathode catalyst supports to investigate the effect on direct methanol fuel cell (DMFC) performance by using rotating disk electrode and fuel cell testing. The results of linear sweep voltammetry (LSV) and cyclic voltammetry (CV) show that the electrocatalytic activity sequence for oxygen reduction reaction (ORR) is Pt/rGO > Pt/MWNTs > Pt/C catalysts. The single cell tests results show that the maximum power densities of DMFC with Pt/C, Pt/MWNTs and Pt/rGO cathode catalysts are 74.0, 74.2 and 3.3 mW cm −2 , respectively. The experimental results indicate that the performance of DMFC is substantially influenced by the structures of cathode catalyst supports. The significant differences in DMFCs performance are due to the compression ratios and hydrophilic/hydrophobic properties of catalyst layers with different structures of carbon supports, which strongly affect electrochemical active sites and mass transport in cathode catalyst layers. Long-term testing of DMFCs indicates that Pt/MWNTs exhibits superior stability. Considering the factors of the power and lifetime comprehensively, MWNTs is optimal candidate among the three investigated carbon supports. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) structured Pt/C/graphene aerogel (Pt/C/GA) hybrid as a remarkable high stability electrocatalyst is synthesized through a facile and green hydrothermal process. Thanks to the unique 3D graphene framework structure, Pt/C/GA hybrid catalyst demonstrated enhanced stability towards methanol electrooxidation with no decrease of electrocatalytic activity. Besides, Pt/C/GA hybrid catalyst also exhibits a significantly enhanced stability to scavenge crossover methanol under the high potential in acid solution compared with the standard Pt/C catalyst: Pt/C catalyst lost nearly 40% of its initial activity after 1000 cyclic voltammetry cycles, by contrast, only 16% for Pt/C/GA. Moreover, it is noteworthy that after 200 cycles, the mass activity of Pt/C/GA is always much higher than that of Pt/C. A significant stability enhancement is achieved due to the unique 3D macroporous graphene structure as well as the efficient assembly between the Pt/C catalyst and graphene aerogel. Importantly, our synthetic strategy can be easily applied to the commercial PtRu/C catalyst to improve its durability. This simple, convenient and green synthetic method highlights the potential in fabrication of high durable electrocatalyst for fuel cell applications. [ABSTRACT FROM AUTHOR]

Dry–rewetting (DW) disturbance frequently occurs in soils due to rainfall and irrigation, and the frequency of DW cycles might exert significant influences on soil microbial communities and their mediated functions. However, how microorganisms respond to DW alternations in soils with a history of heavy metal pollution remains largely unknown. Here, soil laboratory microcosms were constructed to explore the impacts of ten DW cycles on the soil microbial communities in two contrasting soils (fluvo-aquic soil and red soil) under three copper concentrations (zero, medium and high). Results showed that the fluctuations of substrate induced respiration (SIR) decreased with repeated cycles of DW alternation. Furthermore, the resistance values of substrate induced respiration (RS-SIR) were highest in non-copper-stressed (zero) soils. Structural equation model (SEM) analysis ascertained that the shifts of bacterial communities determined the changes of RS-SIR in both soils. The rate of bacterial community variance was significantly lower in non-copper-stressed soil compared to the other two copper-stressed (medium and high) soils, which might lead to the higher RS-SIR in the fluvo-aquic soil. As for the red soil, the substantial increase of the dominant group WPS-2 after DW disturbance might result in the low RS-SIR in the high copper-stressed soil. Moreover, in both soils, the bacterial diversity was highest in non-copper-stressed soils. Our results revealed that initial copper stress could decrease the resistance of soil microbial community structure and function to subsequent DW disturbance. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) is a globally important nitrogen-cycling process mediated by specialized microbes, and has been demonstrated to be ubiquitous in anoxic natural settings and bioreactors. However, our knowledge of its prevalence in different paddy soil types and along the depth profiles remains largely undocumented. Here, mesocosm incubations were constructed to investigate the activity and community compositions of anammox bacteria across different depth layers of three different paddy soils. 15 N tracer experiments showed that anammox rates were prevalent in almost all depth layers of an inceptisol (Binhai, BH) and an oxisol (Leizhou, LZ), but was absent in an ultisol (Taoyuan, TY). The functional gene hzsB of anammox bacteria was only detected in BH and LZ soil profiles with detected anammox activity. Anammox accounted for 0.4%–12.2% of the total N 2 production, and anammox rates were 0.02–0.77 nmol N g −1 dry soil h −1 and significantly correlated with soil pH and electric conductivity. Anammox activity and abundance of hzsB genes were significantly lower in the surface soil layers (0–5 cm) than in the sub-surface soil layers (20–60 cm). Candidatus Brocadia, Candidatus Kuenenia and Candidatus Jettenia were detected by cloning and sequencing, with Candidatus Brocadia being dominant in all the three soils and Candidatus Jettenia being more frequently detected in the LZ soil. The operational taxonomic unit number and diversity indices of anammox bacterial 16S rRNA gene increased with soil depth. Our results demonstrate that anammox is more common and active in alkaline soils than in acidic soils, in deep paddy soil layers than in surface soil layers, and that anammox activities are likely to be regulated by soil chemical properties such as pH, salinity and redox potential. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4 ) has been demonstrated as an advanced support material for Pt nanoparticles (NPs) due to its excellent stability and abundant Lewis acid for anchoring metal NPs. However, its non-conductive nature and low surface areas still impede its application in electrochemical fields. Herein, a π–π stacking method is presented to prepare graphene/ultrathin g-C 3 N 4 nanosheets composite support for PtRu catalyst. The weaknesses of g-C 3 N 4 are greatly overcome by establishing a 2D layered structure. The significantly enhanced performance for this novel PtRu catalyst is ascribed to reasons as follows: the homogeneous dispersion of PtRu NPs on g-C 3 N 4 nanosheets due to its abundant Lewis acid sites for anchoring PtRu NPs; the excellent mechanical resistance and stability of g-C 3 N 4 nanosheets in acidic and oxidative environments; the increased electron conductivity of support by forming a layered structure and the strong metal-support interaction (SMSI) between metal NPs and g-C 3 N 4 NS. [ABSTRACT FROM AUTHOR]

Two coumarin-based fluorescence probes, 1 and 2 , containing a methoxy oxalyl group as a reaction site were developed. These two novel probes displayed an instant turn-on fluorescence response specific towards Pi without interference from ATP and PPi. A selective 23-fold increase in fluorescence for 1 (in DMSO–HEPES) and a 20-fold increase for 2 (in DMSO) were observed. The proposed sensing mechanism for these compounds is Pi-triggered acetamide bond cleavage leading to release of the blue fluorophore coumarin, which was supported by 1 H NMR and mass spectrometry data. Probe 1 was successfully used to image endogenous and exogenous Pi in living cells and to trace Pi released from ATP by apyrase in Caenorhabditis elegans . [ABSTRACT FROM AUTHOR]

Highlights: [•] We synthesized a highly selective and sensitive colorimetric signal-responding anion-sensor 1. [•] The solution of 1 changed from yellow color to red for F−, to orange for AcO− and to brown for OH−. [•] The color changes of F− are attributed to the deprotonation of the hydroxyl moiety in the binding group. [•] The commonly competing ions induced none or relatively negligible optical perturbations in the UV–Vis spectral analyses. [Copyright &y& Elsevier]

Abstract: Four new C18-diterpenoid alkaloids, weisaconitines A–D (1–4), were isolated from Aconitum weixiense. Based on extensive UV, IR, MS, 1D and 2D NMR analyses, their structures were elucidated as 8-O-ethyldolaconine (1), 4-demethylgenicunine B (2), 14-oxoaconosine (3), and 8-O-ethylaconosine (4). The analgesic activity of compound 4 was studied with CH3COOH-induced writhing model in mice. Compound 4 showed writhing inhibitions of 24% (50mg/kg), 26% (100mg/kg) and 34% (200mg/kg), respectively, as compared to the reference drug aspirin (63%) at a dose of 200mg/kg. [Copyright &y& Elsevier]

Abstract: The perovskite proton conductor BaZr0.9Y0.1O2.95 (BZY10) shows better chemical stability but lower conductivity than BaCe0.9Y0.1O2.95 (BCY10). In this paper we attempted to synthesize BCY10:BZY10 core–shell materials in which BCY10 particles prepared by solid reaction were wrapped by a sol–gel deposited thin layer of BZY10 with ZnO as sintering aid to improve the sinterability of the materials. The effects of the BCY10/BZY10 ratios on the phase purity, microstructure, chemical stability and electrical conductivity of the samples were characterized by XRD, TEM, SEM, TGA and electrochemical impedance spectroscopy. A dense core–shell structure was formed after being sintered at 1300°C for 10h. The core–shell samples displayed improved stability against CO2 and water vapor at high temperature. With BCY10/BZY10 ratio varying from 9:1 to 7:3, the core–shell samples became more stable, and the total conductivities decreased. [Copyright &y& Elsevier]

Biological nitrogen fixation (BNF) plays a vital role in nitrogen supply in agricultural ecosystem but is generally impaired by agricultural fertilization. Understanding the trade-off between fertilization and BNF, and the underlying mechanisms are essential to optimize fertilization management for sustainable agriculture production. In this study, we examined the potential rate of asymbiotic N 2 fixation, nif H gene abundance, the composition and co-occurrence network of diazotrophic community in an acidic red soil received different organic and inorganic fertilization regimes for more than 40 years. Our results showed that long-term chemical fertilizer application drastically decreased soil microbial biomass, nitrogenase activity and nif H gene abundance in comparison to the unfertilized control. Organic manure application showed significantly positive effect on soil nitrogenase activity and crop yield via regulating soil pH and the key ecological cluster of diazotrophic community (module #2 which was mainly represented by Bradyrhizobium , Pseudacidovorax and Azospirillum), while phosphorus fertilization showed no obvious promotion effect. Organic manure amendment significantly increased the diversity of diazotrophs and enriched some diazotrophic taxa, particularly Pseudacidovorax and Rhodopseudomonas which were likely responsible for the high N 2 -fixation potential. The control and organic manure amendment treatments possessed a more complex and stable diazotrophic network than the chemical fertilizer treatments did, which greatly facilitated the resistance of diazotrophic community to environmental stress and thus sustained a high N 2 fixation potential. Together, our study demonstrated that organic manure application can effectively alleviate the inhibitory effect of nitrogen fertilization on N 2 fixation via regulating soil property and shaping a more stable diazotrophic network. • Long-term N fertilization markedly inhibited BNF and nif H gene size in red soil. • Organic manure largely mitigated the inhibitory effect of N fertilization on BNF. • Phosphorus fertilization showed slight promotion effect on BNF. • Chemical fertilizer application reduced the stability of diazotrophic community. • Organic manure shaped a more complex diazotrophic community and enriched key taxa. [ABSTRACT FROM AUTHOR]

• Dazomet fumigation significantly suppressed pathogen, as well as soil microbes. • Bacteria recovered from fumigation suppression more quickly than fungi. • Fumigation simplified microbial associations and enriched beneficial microbes. • Healthy plant rhizosphere steered a highly connected association network. • Non-FON Fusarium was markedly enriched in healthy plant rhizosphere. Soil fumigation is an effective method to control soil-borne diseases like Fusarium wilt, however the processes and mechanisms driving microbial community reestablishment and pathogen suppression in the rhizosphere after fumigation remain poorly understood. In this study, we examined the dynamics of the rhizosphere microbiome and microbial network associations across different watermelon development stages and plant statuses (i.e. healthy and dead) after soil fumigation and organic fertilizer (OF) application in plastic shelters with Fusarium oxysporum f. sp. niveum (FON) heavily infected. Our results showed that fumigation treatments significantly reduced Fusarium wilt disease incidence and pathogen abundance, meanwhile, decreased soil microbial metabolic activity, fungal biomass and diversity. Bacterial community recovered from fumigation suppression in a short period, while fungal suppression was longer lasting, resulting in decreased fungi to actinomycetes (F/A) and fungi to bacteria (F/B) ratios in PLFA profiles. We further found some bacterial families, such as Actinospicaceae within Actinobacteria, Haliangiaceae , Rhizobiaceae and uncultured Rhodospirillales within Proteobacteria, Sporolactobacillaceae and Limnochordaceae within Firmicutes were greatly enriched after fumigation and might potentially contribute to pathogen suppression. The fumigation treatments significantly reduced microbial network complexity and the percentage of fungal nodes in comparison to un-fumigated control treatment. In contrast, a more complex microbial network was observed in the rhizosphere soil of healthy plants than that in the soil surrounding dead plant roots within fumigation treatments. Furthermore, healthy plant rhizosphere significantly enriched potential beneficial and nitrogen cycle-related bacterial phyla like Gemmatimonadetes, Verrucomicrobia, and Nitrospirae. More interestingly, Fusarium were markedly enriched in the rhizosphere soil of healthy plants and mainly represented by non-FON Fusarium like F. verticillioides and F. solani , implying a potential niche competition between FON and nonpathogenic Fusarium species in the rhizosphere of healthy watermelon. Taken together, our results provide vital information on the reconstruction of microbial communities and potential interactions between plant and its beneficial consortium after fumigation, which is instructive to develop more systematic strategies through targeting both beneficial and pathogen-similar taxa to improve disease control and soil suppression. [ABSTRACT FROM AUTHOR]

Denitrification and anammox are the main pathways of N loss in wet habitats while their relative contribution to N 2 production and underlying microbial mechanisms across marine-terrestrial ecotone remain unclear. Here we investigated the rates of anammox and denitrification, and the distribution patterns of anammox bacteria and nosZ clade I and II denitrifiers across coastal tidal flat to inland paddy soils. Results showed that denitrification dominated the N 2 production over anammox in all samples, accounting for 87.1%–100% of total N 2 production. Coincident with the rate, the abundance of nosZ clade I and II genes were 1–2 orders of magnitude higher than those of hzsB gene. The community of anammox bacteria was mainly driven by salinity while nosZ clade I and II denitrifiers communities were mainly determined by both salinity and pH. Alphaproteobacteria dominated in the nosZ clade I community in all samples while Betaproteobacteria and Gammaproteobacteria were mainly present in low salinity wetland and paddy soils. The nosZ clade II community was composed of more phyla, in which Bacteoidetes and Chloroflexi were ubiquitous while Gemmatimonadetes was present only in low salinity wetland and paddy soils. These findings have direct implications for explicitly incorporating both nosZ clade I and II into future N loss estimation and N 2 O mitigation in marine-terrestrial ecotone. Unlabelled Image • Denitrification dominantly contributed to N 2 production over anammox. • The nosZ type I and type II gene numerically dominated over the hzsB gene. • nosZ I community was exclusively dominated by α-Proteobacteria in tidal flat. • Gemmatimonadetes -belonging nosZ II denitrifier was sensitive to high salinity. • Both salinity and pH were main factors shaping the nosZ clade I and II community. [ABSTRACT FROM AUTHOR]

Long-term livestock grazing often comes with inputs of manure and urine of animals to grassland soils and can influence the microbial communities. However, the effects of grazing on the diversity and abundance of soil antibiotic resistance genes (ARGs) are still obscure. Here we profiled soil resistome using high-throughput quantitative PCR analysis from desert and typical grasslands (Siziwang and Xilingol steppe, respectively) in Inner Mongolia, each with four grazing intensities (no grazing, light grazing, moderate grazing, and heavy grazing). Totally, 54 and 39 ARGs were detected in the Siziwang steppe and the Xilingol steppe, respectively. The relative abundance of ARGs significantly decreased in the Siziwang steppe or remained unchanged in the Xilingol steppe along the gradient of increasing grazing intensity. Mobile genetic elements (MGEs) were significantly and positively correlated with ARGs in the Siziwang steppe but not in the Xilingol steppe. Structural equation model revealed that grazing indirectly affected ARGs through its impact on MGEs, bacterial diversity, and bacterial community composition. These findings suggest that livestock grazing can impact soil resistome via regulating microbiome in grassland soils. However, grazing intensity has not resulted in a significant impact on the soil resistomes in these desert and typical grasslands. Unlabelled Image • Grassland soils are important reservoirs of antibiotic resistance genes (ARGs). • Grazing decreased or did not change the relative abundance of ARGs. • Grazing intensities had indistinctive effects on soil resistome. • Microbial community affected ARGs in grazing grassland soils. [ABSTRACT FROM AUTHOR]