Abstract  High CO2 is able to ameliorate some negative effects due to climate change and intensify others. This study involves the sweet cherry (Prunus avium) cultivar 'Burlat' grafted on the 'Mariana 2624', 'Adara' and 'LC 52' rootstocks. In a climate chamber at two CO2 concentrations, ambient (400 µmol mol(-1) ) and elevated (800 µmol mol(-1) ), the plants were submitted to waterlogging for 7 d, followed by 7 d of recovery after drainage. Waterlogging drastically decreased the rate of photosynthesis, significantly endangering plant survival, particularly for the 'LC 52' and 'Adara' rootstocks. 'Mariana 2624' was also clearly affected by waterlogging that increased lipid peroxidation and the Cl(-) and SO4(2-) concentrations in all the studied plants. Nevertheless, CO2 was able to overcome this reduction in photosynthesis, augmenting growth, increasing soluble sugars and starch, raising turgor and regulating the concentrations of Cl(-) and SO4(2-) , while lowering the NO3(-) concentration in leaves of all the studied rootstocks. In concordance with these results, the proline levels indicated a more intense stress at control CO2 than at high CO2 for waterlogged plants. 'Mariana 2624' was more resistant to waterlogging than 'Adara', and both were more resistant than 'LC 52' in control CO2 conditions; this clearly enhanced the chance of survival under hypoxia.

Abstract  5,10,15,20-Tetrakis(4-sulfonatophenyl)porphyrinato iron(III) chloride (FeTPPS) is a water-soluble heme analog, which has been used as a scavenger of peroxynitrite in many studies. Similar to heme, it may also possess pseudo-peroxidase activity that could cause protein tyrosine nitration through the peroxidase-H2O2-NO2- pathway. In this paper, we used western blotting and spectrophotometry analysis to study the capability of FeTPPS in catalyzing protein tyrosine nitration. Furthermore, the capability of FeTPPS in catalyzing protein nitration in tissue homogenate and cultured cells was also investigated. Our results showed that FeTPPS induced bovine serum albumin (BSA) nitration in the presence of H2O2 and NaNO2, and the reaction was dose-, time- and pH-dependent. In acidic condition, more protein was nitrated by FeTPPS than heme, which corresponded to their peroxidase activities. Meanwhile, our results also confirmed the catalytic effect of FeTPPS on protein tyrosine nitration in rat brain homogenate and human hepatocellular carcinoma (HepG2) cells. At the end of this study, we used liquid chromatography (LC)-tandem mass spectrometry (MS/MS) to investigate differences of site selectivity between heme and FeTPPS catalyzed protein tyrosine nitration. The result indicated that FeTPPS tended to catalyze tyrosine residues locating in more hydrophilic sites, whereas heme was more likely to induce nitration of tyrosine residues locating in relatively hydrophobic environment. Taken together, this is the first report that FeTPPS is an effective and convenient nitration catalyzer in vitro, and this study confirms that the hydrophilicity of the nitrating agents would play an important role in nitration site selection.

Abstract  Understanding how water and solutes enter and propagate through freshwater landscapes in the Anthropocene is critical to protecting and restoring aquatic ecosystems and ensuring human water security. However, high hydrochemical variability in headwater streams, where most carbon and nutrients enter river networks, has hindered effective modelling and management. We developed an analytical framework informed by landscape ecology and catchment hydrology to quantify spatiotemporal variability across scales, which we tested in 56 headwater catchments, sampled periodically over 12 years in western France. Unexpectedly, temporal variability in dissolved carbon, nutrients and major ions was preserved moving downstream and spatial patterns of water chemistry were stable on annual to decadal timescales, partly because of synchronous variation in solute concentrations. These findings suggest that while concentration and flux cannot be extrapolated among subcatchments, periodic sampling of headwaters provides valuable information about solute sources and subcatchment resilience to disturbance.

Abstract  Accurate estimation of constituent loads is important for studies of ecosystem mass balance or total maximum daily loads. In response, there has been an effort to develop methods to increase both accuracy and precision of constituent load estimates. The relationship between constituent concentration and stream discharge is often complicated, potentially leading to high uncertainty in load estimates for certain constituents, especially at longer-term (annual) scales. We used the loadflex R package to compare uncertainty in annual load estimates from concentration vs. discharge relationships in constituents of interest in agricultural systems, including ammonium as nitrogen (NH4-N), nitrate as nitrogen (NO3-N), soluble reactive phosphorus (SRP), and suspended sediments (SS). We predicted that uncertainty would be greatest in NO3-N and SS due to complex relationships between constituent concentration and discharge. We also predicted lower uncertainty with a composite method compared to regression or interpolation methods. Contrary to predictions, we observed the lowest uncertainty in annual NO3-N load estimates (relative error 1.5-23%); however, uncertainty was greatest in SS load estimates, consistent with predictions (relative error 19-96%). For all constituents, we also generally observed reductions in uncertainty by up to 34% using the composite method compared to regression and interpolation approaches, as predicted. These results highlight differences in uncertainty among different constituents and will aid in model selection for future studies requiring accurate and precise estimates of constituent load.

Abstract  Free nitrous acid (FNA) exerts a broad range of antimicrobial effects on bacteria, although susceptibility varies considerably among microorganisms. Among nitrifiers found in activated sludge of wastewater treatment processes (WWTPs), nitrite-oxidizing bacteria (NOB) are more susceptible to FNA compared to ammonia-oxidizing bacteria (AOB). This selective inhibition of NOB over AOB in WWTPs bypasses nitrate production and improves the efficiency and costs of the nitrogen removal process in both the activated sludge and anaerobic ammonium oxidation (Anammox) system. However, the molecular mechanisms governing this atypical tolerance of AOB to FNA have yet to be understood. Herein we investigate the varying effects of the antimicrobial FNA on activated sludge containing AOB and NOB using an integrated metagenomics and label-free quantitative sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS) metaproteomic approach. The Nitrosomonas genus of AOB, on exposure to FNA, maintains internal homeostasis by upregulating a number of known oxidative stress enzymes, such as pteridine reductase and dihydrolipoyl dehydrogenase. Denitrifying enzymes were upregulated on exposure to FNA, suggesting the detoxification of nitrite to nitric oxide. Interestingly, proteins involved in stress response mechanisms, such as DNA and protein repair enzymes, phage prevention proteins, and iron transport proteins, were upregulated on exposure to FNA. In addition enzymes involved in energy generation were also upregulated on exposure to FNA. The total proteins specifically derived from the NOB genus Nitrobacter was low and, as such, did not allow for the elucidation of the response mechanism to FNA exposure. These findings give us an understanding of the adaptive mechanisms of tolerance within the AOB Nitrosomonas to the biocidal agent FNA.

Abstract  Oxygen minimum zones (OMZs), where the concentrations of oxygen are at analytical detection limits, but sulfate reduction is not occurring, are termed suboxic and typically nitrate serves as the terminal electron acceptor for heterotrophic respiration. Such respiration is highest near the top of OMZs where maxima in nitrite and other redox active species are observed. Within OMZs, the availability of free electrons for reduction reactions (p epsilon) can range from -2 to 10 and at thermodynamic equilibrium could control the oxidation states of essential trace elements like iron and toxic ones like arsenic. In turn, this oxidation/reduction speciation affects trace element solubility and bioavailability, thus controlling their reactivity and transport. Field observations and mesoscale models demonstrate the increasing areal extent of oxygen minimum zones, but whether this in turn affects trace element cycling and fluxes remains to be verified. From current observations, it is difficult to determine the relative importance of in situ processes and lateral transport from boundaries to trace elements' redox cycling, which are typically highly redox- and biologically-active in these systems. Such processes could lead to the co-occurrence of redox species that are not controlled by a unique pe. In order to evaluate the effects of in situ redox processes versus advective/diffusive transport on trace elements, the cycling of nitrate/nitrite, iodate/iodide, Fe(II), As(III)/As(V), and hydrogen sulfide was examined in the low oxygen waters off the Peru shelf to the open South Pacific Ocean during the US GEOTRACES GP16 transect in 2013. Nitrite, Fe(II), and iodide were observed from the shelf to 95 degrees W, while reduced forms of sulfur and arsenic were absent. Maxima in nitrite, Fe(II) and iodide were coincident, indicating the utilization of Fe(III), iodate and nitrate as terminal electron acceptors was possible. For iron, this finding was unexpected with regards to thermodynamics. However, closer inspection combined with advective/diffusive modeling of water column data and Ra-228-based flux calculations, showed that benthic redox processes, coupled with westward isopycnal transport, influenced the chemical composition and redox speciation within the upper OMZ well offshore. This horizontal transport contributed to the coexistence of Fe(II) with nitrate, indicating that Fe redox chemistry is under kinetic, rather than thermodynamic, control.

Abstract  Nitric oxide (NO) plays important role in alleviating abiotic stresses in plants, including those caused by arsenic (As). Here, we examined the effects of endogenous and exogenous NO in Spirodela intermedia W. Koch (Lemnaceae) under As exposure. For this purpose, we evaluated the As content, reactive oxygen species (ROS) levels, membrane damage and enzymatic antioxidant system. The levels of endogenous NO and the activity of nitrate reductase (NR) were also addressed. The As treatment triggered the production of high endogenous levels of NO and a pronounced activation of the antioxidant enzymes; however, it was not sufficient to completely avoid the increment in ROS content and membrane damage. In contrast, exogenous NO decreased the As levels in plants exposed to As and NO donor, mitigating the ROS production and membrane damage, while maintaining a lower activity of the antioxidant enzymes compared with As- treated plants. Exogenous NO further downregulated the NR activity by a negative feedback, while As boosted the NR activity, consistent with the high endogenous levels of NO observed upon As treatment. Our results suggest that both endogenous and exogenous NO play critical roles in alleviating the As- induced oxidative stress in S. intermedia by reducing As uptake, and possibly by acting as an antioxidant molecule.

Abstract  This study reports nutrient dynamics during the "Run-in-", "Batch-" and "Staggered 1 - 3" production phases of African catfish (Clarias gariepinus Burchell, 1822) in commercial warm water recirculation aquaculture systems (RAS) under three different stocking densities, extensive (max 50 kg m(-3); 35 fish tank(-1)), semi-intensive (max 100 kg m(-3); 70 fish tank(-1)) and intensive (max 200 kg m(-3); 140 fish tank(-1)) at similar system volumes of 13.9, 15.1 and 16.9 m(3). The concentrations of the dissolved macronutrients Total Ammonia Nitrogen (TAN, as NH4+-N), nitrite (NO2--N), nitrate (NO3--N), Total Dissolved Nitrogen (TDN), Total Oxidized Nitrogen (TON), phosphorus (measured as ortho-phosphate) (P), potassium (K), calcium (Ca) and magnesium (Mg) were monitored with colorimetric analyses and budgeted for potential use for aquaponics. We found, that stocking density and RAS maintenance affected oxygen thresholds, subsequently affecting nutrient concentrations of NO3--N due to denitrification. K proportionally increased with feed input, while Ca, Mg and P reacted disproportionally, because of precipitation. Highest deviation was observed for TON, especially when oxygen levels dropped < 6 mg L-1. Maintenance intervals, feed ratios and resulting oxygen levels changed dissolved nutrient concentrations, with highest concentrations under intensive stocking density, medium feed input and oxygen > 6 mg L-1, and lowest under semi-intensive stocking density, high feed input and oxygen > 6 mg L-1. Calculated nutrient budgets under consideration of stocking density, feed input and water exchange rates demonstrated that the production conditions affected nutrient availability and output. The macronutrient ratios TDN, P, K, Ca and Mg as well as the physical and chemical parameters changed constantly under production conditions, due to daily adjusted feeding and RAS maintenance. This must be considered during process management, in stand-alone commercial catfish aquaculture as well as in integrated systems such as aquaponics.

Abstract  We investigate the representation of emissions from the largest (Class 3) commercial marine vessels (c3 Marine) within the Community Multiscale Air Quality (CMAQ) model. In present emissions inventories developed by the United States Environmental Protection Agency (EPA), c3 Marine emissions are divided into off-shore and near shore files. Off-shore c3 Marine emissions are vertically distributed within the atmospheric column, reflecting stack-height and plume rise. Near-shore c3 Marine emissions, located close to the US shoreline, are erroneously assumed to occur only at the surface. We adjust the near-shore c3 Marine emissions inventory by vertically distributing these emissions to be consistent with the off-shore c3 Marine inventory. Additionally, we remove near-shore c3 Marine emissions that overlap with off-shore c3 Marine emissions within the EPA files.

The CMAQ model generally overestimates surface ozone (O-3) compared to Air Quality System (AQS) site observations, with the largest discrepancies occurring near coastal waterways. We compare modeled O-3 from two CMAQ simulations for June, July, and August (JJA) 2011 to surface O-3 observations from AQS sites to examine the efficacy of the c3 Marine emissions improvements. Model results at AQS sites show average maximum 8-hr surface O-3 decreases up to similar to 6.5 ppb along the Chesapeake Bay, and increases similar to 3-4 ppb around Long Island Sound, when the adjusted c3 Marine emissions are used.

Along with the c3 Marine emissions adjustments, we reduce on-road mobile NOX emissions by 50%, motivated by work from Anderson et al. 2014, and reduce the lifetime of the alkyl nitrate species group from 10 days to similar to 1 day based on work by Canty et al. 2015, to develop the "c3 Science" model scenario. Simulations with these adjustments further improve model representation of the atmosphere. We calculate the ratio of column formaldehyde (HCHO) and tropospheric column nitrogen dioxide (NO2) using observations from the Ozone Monitoring Instrument and CMAQ model output to investigate the photochemical O-3 production regime (VOC or NOX-limited) of the observed and modeled atmosphere. Compared to the baseline, the c3 Science model scenario more closely simulates the HCHO/NO2 ratio calculated from OMI data.

Model simulations for JJA 2018 using the c3 Science scenario show a reduction of surface O-3 by as much as similar to 13 ppb for areas around the Chesapeake Bay and similar to 2-3 ppb at locations in NY and CT downwind of New York City. These reductions are larger in 2018 than in 2011 due to a change in the photochemical O-3 production regime in the Long Island Sound region and the projected decline of other (non-c3 Marine) sources of O-3 precursors, highlighting the importance of proper representation of c3 Marine emissions in future modeling scenarios.

Abstract  Bioaugmentation was used to upgrade the nitrification process in a full-scale municipal WWTP with an A2/O system. A mixture of nitrifying bacteria was inoculated into the bioreactor for a final concentration of 1% (v/v). The upgrade process took 25 days, and the NH4+-N removals reached 94.6% (increased at least by 75%). The effluent concentrations of COD and NH4+-N stabilized at <30 mg/L and <4 mg/L even when the corresponding influent concentrations were over 300 mg/L and 60 mg/L, which met the first-class requirement of the National Municipal Wastewater Discharge Standards of China (COD ≤ 50 mg/L, NH4+-N ≤ 5 mg/L). The succession of the microbial community showed the enhanced NH4+-N removal efficiency mainly resulted from the persistence of introduced ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), which increased from 0% to 0.4% and from 0.01% to 2.1%, respectively. This bioaugmentation was shown as an effective technology for upgrading or retrofitting conventional systems to tertiary-level.

Abstract  RATIONALE: The isotopic tracer technique is widely used to identify the sources and fate of nitrogen (N) in order to understand the N cycle and contamination in water environments. The stable isotope ratio of ammonium is expected to greatly enhance the tracing analysis by combining it with the traditional nitrate isotope ratio. Diffusion followed by gas-phase trapping is the most commonly applied method for ammonium isotope ratio measurement. Although dissolved organic nitrogen (DON) is abundant in natural water and its breakdown in the diffusion procedure has been reported, the interference of DON with the measurement of ammonium isotope ratios has not been fully examined.

METHODS: This study aims to test the effect of DON contamination by using organic N compounds, viz. humic acid and alanine. A series of diffusion experiments was conducted at a temperature of 80°C for a maximum of 7 days. Ammonia was transferred from alkaline solution and trapped with an acidic filter. This method was applied for samples with ammonium concentrations between 0.5 and 2.0 mg-N/L.

RESULTS: There was no difference between the ammonium N stable isotope ratios for samples with and without added DON compounds; the fractionation between the observed value and the actual value was negligible, in the range of 0.2 to 1.0‰. The modifications of previous studies, i.e. shorter diffusion period, no vigorous shaking and using gas-phase trapping, successfully avoided any breakdown of DON in fresh water samples.

CONCLUSIONS: The modified method provides high precision and accuracy and it is recommended for the analysis of anthropogenically influenced water samples, such as paddy fields, ground water, rivers and lakes.

Abstract  Nitric acid, an air pollutant with strong acidity and oxidizability, can be found in considerable quantities in the gas and aerosol phase. Understanding the role of nitric acid in atmospheric new particle formation is essential to study the complicated nucleation mechanism. Using density functional theory combined with the Atmospheric Clusters Dynamic Code (ACDC), the role of nitric acid in the formation of new particles has been investigated under different atmospheric conditions (different precursor concentrations and temperatures). The results show that nitric acid can form clusters with sulfuric acid and ammonia by hydrogen bond or even proton-transfer interactions. The concentrations of clusters involving nitric acid can be comparable with those of sulfuric acid-ammonia-based clusters, considering the thermodynamic stability combined with the realistic atmospheric concentrations of precursors. Within the atmospheric concentration range, nitric acid can enhance the formation rates of sulfuric acid-ammonia clusters, especially at low temperature, low sulfuric acid concentration and high ammonia concentration. In addition, the new particle formation mechanism indicates that nitric acid can contribute to the cluster formation and the role of nitric acid in the cluster formation pathway is as a "bridge" connecting the smaller and larger clusters.

Abstract  Although Nitrobacter winogradskyi is an important chemoorganotrophic organism for the study of nitrite-oxidizing bacteria physiology as well as nitrification, until now, the mixotrophic medium for this organism growth has not been optimized, comprehensively. In this study, we aimed to improve the growth medium of N. winogradskyi using the one-factor-at-a-time (NaNO2 , glycerol, pH) method. In addition, a further experimental design was carried out based on central composite design with response surface methodology. Different combinations of the three cultural parameters were fitted by multiple regression analysis to calculate the predicted response. Our results suggest that optimal culture condition for the growth of N. winogradskyi was a modified DSMZ 756a medium containing NaNO2 (5·74 g l-1 ) and glycerol (37·88 mmol l-1 ), pH 7·83, a temperature of 28°C and agitation at 120 rev min-1 . The results from a validation experiment (bacterial growth: OD600 1·0293) were close to the value predicted by the quadratic model (OD600 1·0994). In addition, we uncovered the potential mechanism at the cellular and ultrastructural levels. The results indicated that glycerol in the media enhanced the rate of cell division and cell growth by increasing the accumulation of polyphosphates and phosphorus, and high concentrations of NaNO2 provided sufficient energy for growth and contributed to the generation of carboxysomes in cells for CO2 fixation.

SIGNIFICANCE AND IMPACT OF THE STUDY: Due to the extremely slow growth rate and the low growth yield of ammonia-oxidizing bacteria and NOB (nitrite-oxidizing bacteria), nitrification is still the rate-limiting step of nitrogen cycle in the current research. Nitrobacter winogradskyi, an important NOB, participates in the second step of nitrification in water and soil. This study reported an optimized culture condition for N. winogradskyi, which increased the growth yield by 5·06 times than that in the basal medium and uncovered the potential mechanism. We expect our study will contribute to the research on water and soil nitrogen cycle. In addition, the optimized culture conditions have the potential to be suitable for the chemoorganotrophic growth of other nitrifiers.

Abstract  Poly-γ-glutamic acid (γ-PGA) is an important multifunctional biopolymer with various applications, for which adenosine triphosphate (ATP) supply plays a vital role in biosynthesis. In this study, the enhancement of γ-PGA production was attempted through various approaches of improving ATP supply in the engineered strains of Bacillus licheniformis. The first approach is to engineer respiration chain branches of B. licheniformis, elimination of cytochrome bd oxidase branch reduced the maintenance coefficient, leading to a 19.27% increase of γ-PGA yield. The second approach is to introduce Vitreoscilla hemoglobin (VHB) into recombinant B. licheniformis, led to a 13.32% increase of γ-PGA yield. In the third approach, the genes purB and adK in ATP-biosynthetic pathway were respectively overexpressed, with the AdK overexpressed strain increased γ-PGA yield by 14.69%. Our study also confirmed that the respiratory nitrate reductase, NarGHIJ, is responsible for the conversion of nitrate to nitrite, and assimilatory nitrate reductase NasBC is for conversion of nitrite to ammonia. Both NarGHIJ and NasBC were positively regulated by the two-component system ResD-ResE, and overexpression of NarG, NasC, and ResD also improved the ATP supply and the consequent γ-PGA yield. Based on the above individual methods, a method of combining the deletion of cydBC gene and overexpression of genes vgB, adK, and resD were used to enhance ATP content of the cells to 3.53 μmol/g of DCW, the mutant WX-BCVAR with this enhancement produced 43.81 g/L of γ-PGA, a 38.64% improvement compared to wild-type strain WX-02. Collectively, our results demonstrate that improving ATP content in B. licheniformis is an efficient strategy to improve γ-PGA production.

Abstract  Water-soluble organic matter (WSOM) represents a critical fraction of fine particles (PM2.5) in the air, but its changing behaviors and formation mechanisms are not well understood yet, partly due to the lack of fast techniques for the ambient measurements. In this study, a novel system for the on-line measurement of water-soluble components in PM2.5, the particle-into-liquid sampler (PILS)-Nebulizer-aerosol chemical speciation monitor (ACSM), was developed by combining a PILS, a nebulizer, and an ACSM. High time resolution concentrations of WSOM, sulfate, nitrate, ammonium, and chloride, as well as mass spectra, can be obtained with satisfied quality control results. The system was firstly applied in China for field measurement of WSOM. The mass spectrum of WSOM was found to resemble that of oxygenated organic aerosol, and WSOM agreed well with secondary inorganic ions. All evidence collected in the field campaign demonstrated that WSOM could be a good surrogate of secondary organic aerosol (SOA). The PILS-Nebulizer-ACSM system can thus be a useful tool for intensive study of WSOM and SOA in PM2.5.

Abstract  The mature landfill leachate containing high ammonia concentration (>1000 mg/L) is a serious threat to environment; however, the low COD to TN ratio (C/N, <3) strongly inhibits the denitrification process and poses a severe obstacle for efficient treatment. Herein, two kinds of acidogenic liquids, fermented from oil-removed food waste and oil-added food waste, were first applied as external carbon sources for the biological nitrogen removal from mature landfill leachate in an aerobic/anoxic membrane bioreactor. "Acidogenic liquid b" served quite better than commercial sodium acetate, considering the higher denitrification efficiency and the slightly rapider denitrification rate. The effect of C/N and temperature were investigated under hydraulic retention time (HRT) of 7 d, which showed that C/N ≥ 7 (25 °C) was enough to meet the general discharge standards of NH4+-N, TN and COD in China. Even for some special areas of China, the more stringent discharge standards (NH4+-N ≤ 8 mg/L, TN ≤ 20 mg/L) could also be achieved under longer HRT of 14 d and C/N ≥ 6. Notably, the COD concentration in effluent could also be well reduced to 50-55 mg/L, without further physical-chemical treatment. This proposed strategy, involving the high-value utilization of food waste, is thus promising for efficient nitrogen removal from mature landfill leachate.

Abstract  Nitrification plays a crucial role in global nitrogen cycling and treatment processes. However, the relationships between the nitrifier guilds of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) are still poorly understood, especially in freshwater habitats. This study examined the physiological interactions between the AOB and NOB present in a freshwater aquarium biofilter by culturing them, either together or separately, in a synthetic medium. Metagenomic and 16S rRNA gene sequencing revealed the presence and the draft genomes of Nitrosomonas-like AOB as well as Nitrobacter-like NOB in the cultures, including the first draft genome of Nitrobacter vulgaris. The nitrifiers exhibited different growth rates with different ammonium (NH4+) or nitrite concentrations (50-1,500 μM) and the growth rates were elevated under a high bicarbonate (HCO3-) concentration. The half-saturation constant (Ks for NH4+), the maximum growth rate (μmax), and the lag duration indicated a strong dependence on the synergistic relationships between the two guilds. Overall, the ecophysiological and metagenomic results in this study provided insights into the phylogeny of the key nitrifying players in a freshwater biofilter and showed that interactions between the two nitrifying guilds in a microbial community enhanced nitrification.

Abstract  Two lab-scale nitrifying sequencing batch biofilm reactors, with (SBBR_CN) or without the addition of organics (SBBR_N), were operated to investigate potential roles of acyl homoserine lactone (AHL) based quorum sensing. AHLs of N-[(RS)-3-Hydroxybutyryl]-L-homoserine lactone, N-hexanoyl-L-homoserine lactone (C6-HSL) and N-octanoyl-L-homoserine lactone (C8-HSL) were detected in both reactors. C6-HSL and C8-HSL were also detected in batch experiments, especially with stimulated nitrite oxidizing bacteria activities. Quorum sensing affected biofilm formation mainly through the regulation of extracellular protein production. By the metagenomics analysis, many identified genera and species could participate in quorum sensing, quorum quenching and extracellular polymeric substances (EPS) production. A high quorum quenching activity was obtained in SBBR_CN, whereas a high quorum sensing activity in SBBR_N. Nitrosomonas-like ammonia oxidizing bacteria, Nitrospira-like nitrite oxidizing bacteria and Comammox harbored genes for AHL synthesis and EPS production. Possible relationships among AHLs synthesis, biofilm formation and nitrifiers activity were proposed.

Abstract  An efficient coordination high-speed counter-current chromatography method for the preparative separation of ginkgolic acids from the sarcotesta of Ginkgo biloba L was developed. The type, concentration, and mechanism of the coordination agent were investigated. Following the use of four types of metal salts including silver nitrate, copper chloride, ferric chloride, and aluminium nitrate, n-heptane-ethyl acetate-methanol-acetic acid (5:4:1:1, v/v) with 0.20 mol/L silver nitrate as the coordination agent was chosen as the optimum two-phase solvent system. Five main ginkgolic acids including C13:0, C15:0, C15:1, C17:1 and C17:2 were successfully separated with purities greater than 98%. The sample loading was 500 mg, the flow-rate was 2.0 mL/min, rotation speed was 800 revolutions per minute and temperature was 20°C. The structures of the separated ginkgolic acids were identified by standard samples and electrospray ionization mass spectrometry. The introduction of coordination chemistry in high-speed counter-current chromatography is novel and effective for the preparative separation and isolation of ginkgolic acids from the sarcotesta of Ginkgo biloba L and could also be applied to separate compounds which form coordination bonds in other complex natural products. This article is protected by copyright. All rights reserved.

Abstract  Herein, on a zinc substrate, a superhydrophobic Co5Zn21 alloy surface with a nanometer needle structure was fabricated by immersing processed Zn sheets perpendicularly into a cobalt(II) nitrate aqueous solution followed by the annealing treatment. This alloy surface exhibited not only outstanding superhydrophobicity with a water contact angle of 1601 but also excellent mechanical durability and corrosion resistance. The morphology and chemical composition of the superhydrophobic surface (SHS) were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction pattern (XRD), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the samples was characterized via polarization, Nyquist, and bode modulus plots. The SHS endures mechanical stretch for more than 800 mm of abrasion using sandpaper with different grit sizes (P1200, P800, and P400) and shows abrasion resistance. When the super-hydrophobic surface lost its superhydrophobicity after a long-term damage, the superhydrophobicity could be easily regenerated again by immersion and annealing treatment. The surface after repair can still maintain its superhydrophobicity after anti-friction, anti-ice, and UV irradiation tests.

Abstract  Mountain ecosystems are sensitive and reliable indicators of climate change. Long-term studies may be extremely useful in assessing the responses of high-elevation ecosystems to climate change and other anthropogenic drivers from a broad ecological perspective. Mountain research sites within the LTER (Long-Term Ecological Research) network are representative of various types of ecosystems and span a wide bioclimatic and elevational range. Here, we present a synthesis and a review of the main results from ecological studies in mountain ecosystems at 20 LTER sites in Italy, Switzerland and Austria covering in most cases more than two decades of observations. We analyzed a set of key climate parameters, such as temperature and snow cover duration, in relation to vascular plant species composition, plant traits, abundance patterns, pedoclimate, nutrient dynamics in soils and water, phenology and composition of freshwater biota.& para;& para;The overall results highlight the rapid response of mountain ecosystems to climate change, with site-specific characteristics and rates. As temperatures increased, vegetation cover in alpine and subalpine summits increased as well. Years with limited snow cover duration caused an increase in soil temperature and microbial biomass during the growing season. Effects on freshwater ecosystems were also observed, in terms of increases in solutes, decreases in nitrates and changes in plankton phenology and benthos communities. This work highlights the importance of comparing and integrating long-term ecological data collected in different ecosystems for a more comprehensive overview of the ecological effects of climate change. Nevertheless, there is a need for (i) adopting co-located monitoring site networks to improve our ability to obtain sound results from cross-site analysis, (ii) carrying out further studies, in particular short-term analyses with fine spatial and temporal resolutions to improve our understanding of responses to extreme events, and (iii) increasing comparability and standardizing protocols across networks to distinguish local patterns from global patterns. (C) 2017 Elsevier B.V. All rights reserved.

Abstract  Forest fires are a regular occurrence in the Mediterranean basin. High severity fires and post-fire management can affect biological, chemical and physical properties of soil, including the composition and abundance of soil microbial communities. Salvage logging is a post-fire management strategy, which involves the removal of burnt wood from land after a fire. The main objective of this work was to evaluate the impact of post-fire salvage logging and microaggregation on soil microbial communities, specifically on the abundance of nitrogen cyclers and, thus, the potential of the soil for microbial nitrogen cycling. The abundance of nitrogen cyclers was assessed by quantification of microbial nitrogen cycling genes in soil DNA, including nifH (involved in nitrogen fixation), nirS/K and nosZ (involved in denitrification), amoA-B and amoA-Arch (involved in bacterial and archaeal nitrification, respectively). It was demonstrated that salvage logging reduced bacterial load post-fire when compared to tree retention control and resulted in significant changes to the abundance of functional bacteria involved in nitrogen cycling. Microbial gene pools involved in various stages of the nitrogen cycle were larger in control soil than in soil subjected to post-fire salvage logging and were significantly correlated with organic matter, available phosphorous, nitrogen and aggregate stability. The microaggregate fraction of the soil, which has been associated with greater organic carbon, was shown to be a hotspot for nitrogen cyclers particularly under salvage logging. The impact of post-fire management strategies on soil microbial communities needs to be considered in relation to maintaining ecosystem productivity, resilience and potential impact on climate change.

Abstract  The Sr-free mixed ionic electronic conducting perovskites La0.8Ca0.2FeO3-delta (LCF82) and Pr0.8Ca0.2FeO3-delta (PCF82) were synthesized via a glycine-nitrate process. Crystal structure, phase purity, and lattice constants were determined by XRD and Rietveld analysis. The oxygen exchange kinetics and the electronic conductivity were obtained from in-situ dc-conductivity relaxation experiments at 600-800 degrees C and 1x10(-3)<= pO(2)/bar <= 0.1. Both LCF82 and PCF82 show exceptionally fast chemical surface exchange coefficients and chemical diffusion coefficients of oxygen. The oxygen nonstochiometry of LCF82 and PCF82 was determined by precision thermogravimetry. A point defect model was used to calculate the thermodynamic factors of oxygen and to estimate self-diffusion coefficients and ionic conductivities. Density Functional Theory (DFT) calculations on the crystal structure, oxygen vacancy formation as well as oxygen migration energies are in excellent agreement with the experimental values. Due to their favourable properties both LCF82 and PCF82 are of interest for applications in solid oxide fuel cell cathodes, solid oxide electrolyser cell anodes, oxygen separation membranes, catalysts, or electrochemical sensors.

Abstract  Two known lanthanide complexes, [KLa(HL1)(2){(CH3)(2)NCHO} 2(H2O)(3)] (1) and [Sm(H2O)(9)](E-H2L2)(3)center dot 2H(2)O (2) were prepared by reaction of lanthanum(III) and samarium(III) nitrates with potassium 3-(2-(2,4-dioxopentan-3-ylidene) hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonate (KH2L1) and potassium (E, Z)--5chloro-3-(2-(1,3-dioxo-1-phenylbutan-2-ylidene) hydrazinyl)-2-hydroxybenzenesulfonate (KH2L2), respectively. Catalytic activities of 1 and 2 were evaluated in the cyanosilylation of aldehydes with trimethylsilyl cyanide in different solvents such as tetrahydrofuran, dichloromethane or methanol. Complex 1 was found to be efficient catalyst for the cyanosilylation reaction in methanol medium at room temperature, producing cyanohydrin trimethylsilyl ethers with good yields (76-99%). (C) 2017 Elsevier B.V. All rights reserved.

Abstract  Cerium (Ce) belongs to the rare earth elements (REEs), and although it is not essential for plants, it can stimulate growth and other physiological processes. The objective of this research was to evaluate the effect of Ce on seed germination, initial seedling growth, and vegetative growth in rice (Oryza sativa L.) cv. Morelos A-98. During the germination process, the seeds were treated with Ce concentrations of 0, 4, 8, and 12 μM; after 5 d, germination percentage was recorded and after 10 d seedling growth was measured. For vegetative growth, a hydroponic system was established where 14-d-old plants without previous Ce treatment were transferred into nutrient solution. After two weeks of acclimatizing, 0, 25, 50, and 100 μM Ce were added to the nutrient solution for 28 d. Ce significantly increased germination and the initial growth variables of the seedlings. During vegetative growth, Ce increased plant height, number of tillers, root volume, and shoot fresh and dry biomass, without affecting root biomass weight. With low Ce concentrations (25 and 50 μM), the concentrations of chlorophylls and amino acids in the shoots were similar to those in the control, like amino acid concentration in the roots at a concentration of 25 μM Ce. Conversely, the concentration of total sugars increased in the shoot with the application of 25, 50, and 100 μM Ce, and in the roots with the application of 50 μM Ce. Also, Ce did not affect the concentration of macro or micronutrients in the shoots. However, in the roots, the high Ce concentration decreased the concentrations of Ca, Fe, Mn, and Zn, while the Mg concentration increased. Our results indicate that Ce, at the right concentrations, can function as a biostimulant in rice germination and growth.