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Electrochemical redox is an effective method to degrade halogenated organic pollutants (HOPs). Herein, highly dispersed Pd-polypyrrole (Pd-PPy) catalysts were synthesized by a facile one-step polymerization method. The morphology and phase structure of the catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrochemical redox of 4-fluorophenol (4-FP) was conducted in a single-chamber reactor with Pd-PPy as a moveable catalyst. The effects of the initial solution pH, constant current, and supporting electrolyte on the degradation of 4-FP were investigated. The removal efficiency of 4-FP was 84.6% after 2 h under an initial solution pH of 2.5 and an applied current density of 2.0 mA/cm2. The mechanism of 4-FP degradation was inferred, including the defluorination of 4-FP on the cathode and oxidation of 4-FP and phenol on the anode. The degradation of 4-FP in the Pd-PPy-mediated reactor showed lower energy consumption and higher removal efficiency. The degradation efficiency of 4-FP had almost no change after 20 cycles of experiments, which indicates the good durability of the prepared Pd-PPy catalysts.

A Sb-doped SnO2 anode modified with Ni and B was fabricated by the sol–gel method. The effect of major operation parameters of electrode preparation, such as Ni content, B content, and calcination temperature, on the mineralization degree of phenol was investigated. Response surface methodology was used to optimize the experimental conditions and evaluate the association between various operation parameters. The morphology, crystal structure, and electrocatalytic performance of the prepared SnO2–Sb–Ni–B anodes were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), linear sweep voltammetry (LSV), and cyclic voltammetry (CV). The optimized sol–gel preparation ratio of citric acid, ethylene glycol, tin tetrachloride, antimony trichloride, nickel chloride, and boric acid was 650:200:100:6.5:0.5:2, and the calcination temperature of the electrode was 550 °C. The SnO2–Sb–Ni–B anode has the highest oxygen evolution potential of 1.63 V (vs. Hg2/Hg2SO4). The removal degree of phenol reached 58% within 2 h on the SnO2–Sb–Ni–B anode. The accelerated lifetime of the selected SnO2–Ni–B anode was 720 min, which was carried out in a 3-mol/L sulfuric acid solution with a current density of 500 mA/cm2.

In this article, we present the optimal strategy for public plug-in electric vehicle (PEV) charging services with multiple charging options: fast charging service and slow charging service. The PEV user make decisions by firstly considering the remaining energy, travel distance to charging station, then about the charging prices, charging rates and estimated charging time. To obtain insights of such a highly coupled system, we consider both monopoly and duopoly markets, where the two services are operated by a single service provider (SP) and two different SPs, respectively. For the monopoly market, we propose a three-stage Stackelberg game model. For the duopoly market, we propose a two-stage Bertrand competition and Cournot competition. We provided the SP’s optimal pricing strategies and decisions in the monopoly market, and the optimal pricing contract and quantity contract for SPs in the duopoly market with Bertrand competition and Cournot competition. Both the analytical and simulation results show that, in the monopoly market, offering two charging options can potentially improve the SP’s profit compared with offering one option only in the monopoly market; while in the duopoly market, it is optimal for SPs to offer the quantity contract rather than the price contract to maximize profits.

Various metal cations M (M = Mg

Leaf trait-based research has become the preferred method to understand the ecological strategies of plants. However, there is still a debate on whether area-based or mass-based traits provide different insights into environmental adaptations and responses. In this study, seven key leaf traits (maximum net photosynthetic rate, dark respiration rate, nitrogen content, photosynthetic nitrogen use efficiency, leaf mass per area, leaf dry matter contents and leaf area) of 43 woody species were quantified on the basis of both area and mass along an altitudinal gradient (1100–2700 m) in the Qinling Mountains of China. Differences in leaf traits and bivariate correlations between the two expressions were compared. By considering different expressions, the strengths and directions of the responses of leaf traits to the altitudinal gradient were determined. Leaf traits showed large variations; interspecific variations contributed more to total variance than intraspecific variations. Bivariate correlations between photosynthetic traits and structural traits (mass per area, dry matter content, and area) were weaker on a mass basis than those on an area basis. Most traits exhibited quadratic trends along the altitudinal gradient, and these patterns were more noticeable for area-based than mass-based traits. Area-based traits were more sensitive to changes in temperature and precipitation associated with altitude. These results provide evidence that mass- versus area-based traits show different ecological responses to environmental conditions associated with altitude, even if they do not contain very broad spatial scales. Our results also indicate distinction of photosynthetic acclimation among the two expressions along an altitudinal gradient, reflecting trade-offs among leaf structure and physiological traits.

The exposure pathways and environmental impacts of titanium dioxide nanoparticles (TiO2 NPs) released into soils could be significantly influenced by their stability and transport behaviors. The aim of this study was to investigate the stability and transport of TiO2 NPs in three variable-charge soils and to determine the key factors controlling these behaviors. Three surface (0~15 cm) variable-charge soils derived from quaternary red clay, humid ferralsols and stagnic anthrosols collected from Yingtan, Jiangxi Province (YT-H and YT-S, respectively), and humid ferralsols collected from Fuyang, Zhejiang Province (FY-H), were used in this study. Batch sedimentation experiments of TiO2 NPs in soil suspensions were performed for 10 h to quantify their stability. Transport of TiO2 NPs in soil columns was conducted with and without the presence of fulvic acid (FA). Apart from soil organic matter (SOM) and iron oxides, there was no significant difference between the tested soils. Batch experiments showed that TiO2 NPs were more stable in the YT-S soil suspension with high dissolved organic matter than in the YT-H and FY-H soil suspensions. In the column experiments, all TiO2 NPs were retained in YT-H and YT-S, while 11% of the TiO2 NPs were eluted from FY-H with a low amorphous iron oxide content. The significant retention of TiO2 NPs in the soils could be attributed to the straining and adsorption of TiO2 NPs on the surface of soil particles. FA enhanced the transport of TiO2 NPs in YT-H and FY-H by dispersing the TiO2 NPs and reducing their adsorption onto soil particles, while all the TiO2 NPs dispersed in the FA solution were still deposited in YT-S with a high amorphous iron oxide content. The stability of TiO2 NPs in three variable-charge soil suspensions was dependent on the SOM. However, the mobility of TiO2 NPs in soils was not directly related to their stability in the soil suspensions. The difference in amorphous iron oxide content could induce the disparity in mobility of TiO2 NPs in soils.

Harvested fruit tissues produce reactive oxygen species (ROS) in response to wounding. ROS production is further elevated when biocontrol yeasts are introduced into the wounds, where they act as a bio-elicitor and this results in an environment in which the biocontrol yeast is subject to oxidative stress. In the present study, the effect of trehalose, a non-reducing disaccharide and a major reserve carbohydrate, on the level of oxidative stress tolerance of the biocontrol yeast Candida oleophila was examined in wounded pear fruits. Results indicated that the level of trehalose in C. oleophila yeast cells increased when they were cultured in a trehalose-containing medium. Exposure to a trehalose-medium and the increase in internal trehalose improved the adaptation of C. oleophila to the oxidative environment present in pear fruit wounds. Trehalose-treated cells exhibited a lower accumulation of ROS and mitochondrial impairment compared to untreated, control cells when they were introduced into wounded pear fruit. The trehalose treatment up-regulated the expression of antioxidant genes, including peroxisomal catalase and thioredoxin reductase, in yeast cells. Trehalose-treated yeast also exhibited a faster growth rate in pear wounds and greater biocontrol efficacy against blue mold (Penicillium expansum) and Alternaria rot (Alternaria alternata) than untreated, control yeast. These results support the premise that trehalose improves the biocontrol efficacy of C. oleophila via the activation of antioxidant defense systems which support a faster rate of growth of the yeast in wounds of pear fruit.

Ammonia borane (AB) (hydrogen donor), was used for the hydrodechlorination of p-chlorophenol on Fe3O4@PPY@Pd at room temperature and pressure. Fe3O4@PPY@Pd was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The high-performance liquid chromatography and carbon balance results showed that p-chlorophenol was efficiently and quantitatively transformed into phenol. At the AB and catalyst contents of 2.5 mmol and 60 mg, respectively, the dechlorination of p-chlorophenol (100 mg/L) followed pseudo-first-order kinetics (rate constant = 0.023 min−1), and removal efficiency up to 92.5% was obtained in 120 min. The apparent activation energy was 31.6 kJ/mol. The Fe3O4@PPY@Pd composite catalyst could be reused without a significant loss in activity. This confirms the good stability of the catalyst. Here, a reductive approach for the dechlorination of organic compounds in water is provided. It is also useful for the fabrication of Pd-based nanocatalysts with easy accessibility, superior activity, and convenient recovery.

Geomechanical properties are essential for safe drilling, successful completion, and exploration of both conven-tional and unconventional reservoirs, e.g. deep shale gas and shale oil. Typically, these properties could be calcu-lated from sonic logs. However, in shale reservoirs, it is time-consuming and challenging to obtain reliable log-ging data due to borehole complexity and lacking of in-formation, which often results in log deficiency and high recovery cost of incomplete datasets. In this work, we propose the bidirectional long short-term memory (BiL-STM) which is a supervised neural network algorithm that has been widely used in sequential data-based pre-diction to estimate geomechanical parameters. The pre-diction from log data can be conducted from two differ-ent aspects. 1) Single-Well prediction, the log data from a single well is divided into training data and testing data for cross validation; 2) Cross-Well prediction, a group of wells from the same geographical region are divided into training set and testing set for cross validation, as well. The logs used in this work were collected from 11 wells from Jimusaer Shale, which includes gamma ray, bulk density, resistivity, and etc. We employed 5 vari-ous machine learning algorithms for comparison, among which BiLSTM showed the best performance with an R-squared of more than 90% and an RMSE of less than 10. The predicted results can be directly used to calcu-late geomechanical properties, of which accuracy is also improved in contrast to conventional methods.

Bioleaching is an effective and promising approach for the recovery or removal of heavy metals from metal-laden municipal solid waste incineration fly ash. To exclude the risk of reacidification of the leached fly ash after bioleaching with sulfur powder, molded sulfur prills were used as energy substrate for sulfur oxidizing bacteria to examine the availability of reusing the recyclable sulfur forms. The chemical species of heavy metals during the bioleaching process were also investigated. Results showed that the pH reduction, sulfate production, and metal solubilization with sulfur prills were comparable to that with sulfur powder despite of the theoretically calculated smaller surface of the formers. After 15 days of bioleaching, 80.7&ndash, 82.1% of Cd, 72.5&ndash, 74.1% of Zn, 42.8&ndash, 43.9% of Cu, 24.1&ndash, 25.2% of Cr, and 12.4&ndash, 13.0% of Pb were removed from the fly ash, respectively. During bioleaching, heavy metals in the acid extractable and reducible fraction were significantly removed, and metals in oxidizable from were partially reduced. The low leaching toxicity of heavy metals according to toxicity characteristic leaching procedure (TCLP) verified the effective detoxification of fly ash. Moreover, the comparable pH reduction and metal removal efficiencies of bioleaching process with recycled sulfur prills to that with fresh sulfur revealed the potential of reusing the recoverable sulfur prills in the bioleaching process for decontamination of heavy metals from municipal solid waste fly ash.

This dataset is related to the research article in Chemosphere, entitled 'The limited facilitating effect of dissolved organic matter extracted from organic wastes on the transport of titanium dioxide nanoparticles in acidic saturated porous media' [1]. The data summarised the characterization of dissolved organic matter (DOM) extracted from organic wastes and their effects on the transport of titanium dioxide nanoparticles (TiO2 NPs) in acidic saturated porous media in the presence of monovalent electrolyte. Three types of dissolved organic matter were extracted from organic materials, including swine manure, sludge, and sediment, using deionized water, and were characterized with UV-Vis, FTIR and elementary analysis. The adsorption of DOM onto TiO2 NPs was evaluated in the presence of NaCl, and zeta potentials of TiO2 NPs were also determined. Breakthrough column experiments were conducted to quantify the effects of the extracted DOM on the transport behaviours of TiO2 NPs in acidic porous media compared with humic acid. Moreover, the interaction energy between nanoparticles and between nanoparticles and quartz media was calculated according to the classical DLVO theory. The dataset could be used as a reference for the evaluation and prediction of the environmental fate and subsequent risk of engineered nanomaterials.

This work aimed at investigating electrocatalytic hydrodechlorination (ECH) mechanisms of chlorophenols (CPs) on a Pd-modified cathode. Experiments on the ECH of 2,4-dichlorophenol were conducted under extreme test conditions, i.e., with various buffer solutions and several sodium salt solutions as supporting electrolytes. Buffer solutions promote dechlorination due to their property of retarding the alkalinity of a solution. ECH was found to be significantly inhibited by sulfite. Experimental results showed that sulfite poisoning on Pd catalysts was reversible. Protonation may account, at least in part, for the observed high pH dependency of ECH, which proceeded rapidly, with lower apparent activation energy (Ea) in the acidic electrolyte. In addition, pH influenced the selectivity of dechlorination of CPs. It was inferred that the ECH of CPs on the Pd-modified electrode was a preactivated electrocatalytic reaction.

The control strategy of shifting actuators is the most crucial part in the development of automated mechanical transmission (AMT) system. To solve problems such as large workload of parameters tuning and worse disturbance-rejecting ability under traditional PID for selecting and shifting gear in present industry, a new strategy based on active disturbance rejection control (ADRC) was proposed. The extended state observer (ESO) was used to observe and compensate total disturbances in real time to achieve precise closed-loop control for shifting motor position. The Hardware-In-the-Loop (HIL) experiments show that the speed of selecting actuator moving to target position under ADRC is 14.3% faster than that of PID, and the position deviation of selecting actuator is 0.9mm under ADRC with an external disturbance of 1N·m added, which is 59.1% less than that under PID. And the target gear tracking test indicates that the total shifting time under ADRC can be reduced by 2.37% to 5.08% compared with PID. This strategy has better control accuracy and robustness under load mutation condition compared to traditional PID.

A polypyrrole-modified bimetallic electrode composed of Pd-Ag on a Ti substrate (Pd-Ag/PPY/Ti) was successfully prepared via a chemical deposition method, and was applied to the electrocatalytic hydrodechlorination of 4-chlorophenol (4-CP) in aqueous solution. The electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Various influences on the dechlorination efficiency of 4-chlorophenol, including applied current, initial pH value, and temperature, were studied. The dechlorination efficiency of 4-CP reached 94% within 120 min under the optimum conditions, i.e., a dechlorination current of 6 mA, an initial pH of 2.30, and a temperature of 303 K. The apparent activation energy of the dechlorination of 4-CP by the Pd-Ag/PPY/Ti electrode was calculated to be 49.6 kJ/mol. The equivalent conversion rate constant kPd was 0.63 L.gPd−1·min−1, which was higher than the findings presented in comparable literature. Thus, a highly effective bimetallic electrode with promising application prospects and low Pd loading was fabricated.

Facilitation studies typically compare plants under differential stress levels with and without neighbors, while the density of neighbors has rarely been addressed. However, recent empirical studies indicate that facilitation may be density-dependent too and peak at intermediate neighbor densities. Here, we propose a conceptual model to incorporate density-dependence into theory about changes of plant–plant interactions under stress. To test our predictions, we combine an individual-based model incorporating both facilitative response and effect, with an experiment using salt stress and Arabidopsis thaliana. Theoretical and experimental results are strikingly consistent: (1) the intensity of facilitation peaks at intermediate density, and this peak shifts to higher densities with increasing stress; (2) this shift further modifies the balance between facilitation and competition such that the stress-gradient hypothesis applies only at high densities. Our model suggests that density-dependence must be considered for predicting plant–plant interactions under environmental change., Density-dependence is rarely accounted for in plant-plant facilitation studies. Here the authors develop a framework that incorporates density-dependence in the stress-gradient hypothesis, and test it first through modeling and then empirically on Arabidopsis thaliana along salt stress gradients.

The effects of a biocontrol yeast Candida oleophila and a bio-elicitor, oligogalacturonide (OGA), were evaluated for controlling postharvest gray mold caused by Botrytis cinerea and black rot caused by Alternaria alternata, and natural infection on kiwifruit stored at room temperature. Results indicated that C. oleophila and OGA as individual treatments, markedly inhibited development of gray mold and black rot, as well as natural decay occurrence on kiwifruit, compared to control fruit. A combination of both C. oleophila and OGA, however, provided a better control result than each single treatment. C. oleophila growth in kiwifruit wounds was not significantly affected by OGA. Moreover, C. oleophila and OGA individually or in combination induced gene expression and enzyme activity of the defensive enzymes, peroxidase and phenylalanine ammonia-lyase, in kiwifruit. Collectively, the combined application of a biocontrol yeast and OGA may represent an integrative, effective method to manage postharvest diseases of kiwifruit.

Local-scale study on leaf traits and their relationships in a single species along an environmental gradient is essential for scaling up ecophysiological processes from the leaf to the ecosystem level. Here, we quantified 25 leaf traits of two individual species, Quercus aliena var. acutiserrata (Qa, deciduous) and Quercus spinosa (Qs, evergreen), in the same genus, but with different life-form to investigate the leaf traits and relationship variations within and between species along an altitudinal gradient in the Qinling Mountains. Variations of leaf traits were common along an altitudinal gradient at species level, but with different trends between two species. The relationships between plant functional traits were complex and showed different patterns between two species. Two species show different response patterns and adaptation strategies to environmental gradients. The Qa at high altitude suffers from low temperature stress that breaks its carbon balance and leads to growth restriction, which supports the “source-limitation” hypothesis, while Qs at high altitude possesses an adequate supply of carbon to protect from stress, which supports the “sink- or growth-limitation” hypothesis. The effect of environmental change on leaf traits is greater in leaf form than the genetic relationship.

Postharvest decay and senescence results in significant losses in harvested mushrooms. Integrated management, utilizing different eco-friendly, non-chemical methods, represents a strategy for controlling postharvest decay and reducing economic losses in horticultural crops that is being actively developed and commercialized. In the present study, the use of the biocontrol yeast Pichia kluyveri combined with UV-C treatment was evaluated for its ability to control postharvest decay of king oyster mushrooms (Plerrotus eryngii) caused by Lactococcus lactis subsp. lactis. As stand-alone treatments, the use of P. kluyveri or UV-C significantly reduced disease development, relative to untreated mushrooms. The control effects on L. lactis decay and natural infection were significantly improved by the combination of P. kluyveri and UV-C, compared to either treatment alone. Treatment of mushrooms with P. kluyveri or UV-C alone and in combination also induced the activity the antioxidant enzymes of catalase and superoxide dismutase in treated mushrooms, and also enhanced the accumulation of antimicrobial substances, such as total phenolics and flavonoids. These data indicate that the mode of action by which UV-C enhances the biocontrol efficacy of P. kluyveri may be partially attributed to the elicitation of host defense responses in mushrooms. Integrating the use of a biocontrol agent with UV-C treatment represents an effective strategy for controlling postharvest decay in mushrooms.

To prepare an anode with high catalytic activity, long service life and suitability for electrochemical oxidation of industrial wastewater, a noble Al-doped SnO2-Sb electrode on a porous titanium substrate was prepared via an improved sol-gel process. The Al concentration in the sol for the doped metallic oxide on the electrode was investigated. The surface morphologies of the electrodes were characterized via SEM, EDS, XRD and XPS. The electrochemical properties and stabilities of the anodes were investigated by CV, LSV, EIS and accelerated life tests. The surface of the SnO2-Sb-Al anode was uniform and compact when the amount of doped Al was 2.0 at.%, and it possessed the smallest particle size with a long service life. Moreover, the SnO2-Sb-Al-2 anode had the highest oxygen evolution potential (1.57 V). The mineralization degree of phenol reached 69.2% after 2 h when the effective area of the SnO2-Sb-Al-2 anode was 8 cm2 and the applied current density was 10 mA/cm2. Thus, the electrode is suitable for printing, dyeing, and electroplating, while also having potential applications in the pharmaceutical industry and in wastewater cleanup of other refractory biodegradables.

The complexity of natural dissolved organic matter (DOM) motivates the determination of how DOM from diverse sources affects the environmental behaviors of engineered nanoparticles. Here, three types of DOM, DOM extracted from swine manure (SWDOM), sludge (SLDOM) and sediment (SEDOM), were characterized, and their effects on the transport of titanium dioxide nanoparticles (TiO2 NPs, 30 nm in diameter) were evaluated and compared with those of humic acid (HA). Characterization tests showed differences in the aromaticity and weight-average molecular weight (Mw) properties among the three extracted DOM solutions, and greater distinctions were found between the extracted DOM and HA. All the extracted DOM facilitated TiO2 NPs transport in acidic porous media. Nevertheless, the enhancing effects varied among the different extracted DOM types. SWDOM had a promoting effect on TiO2 NPs mobility that was equivalent to that of SEDOM and much higher than that of SLDOM. However, the facilitating effects of all three extracted DOM types were limited compared to that of HA. Based on the combined analysis of DOM properties and TiO2 NPs transport behaviors, it could be concluded that aromaticity and Mw were the key properties determining the limited promoting effects of DOM on TiO2 NPs mobility, and the specific UV absorbance at 280 nm (normalized by concentration, SUVA280) was a facile and useful indicator of the DOM-promoted transport of TiO2 NPs. These findings revealed that transport potential in the presence of DOM would be overestimated if either HA or fulvic acid were chosen as the DOM model in studies.

Plant-plant interactions are reciprocal and include effects on and response to neighbours. Distinct traits confer competitive effect and response ability, but how specific traits determine effect and response in facilitative interactions has not been studied experimentally. We utilized the model species Arabidopsis thaliana to test for trait dependence of facilitative interactions. Salt-sensitive (sos) mutants or salt-tolerant wild-types were exposed to an experimental salinity gradient with and without intraspecific neighbours and the intensity of plant-plant interactions was measured for three performance variables. We tested whether salt tolerance can predict facilitative effect and response and whether a tradeoff exists between competitive ability and tolerance to stress. Interactions shifted very clearly from negative to positive with increasing stress. Salt-sensitive genotypes were less negatively affected by competition but more dependent on facilitation than were wild-types, indicating a tradeoff between competitive ability and stress tolerance. Surprisingly, sensitive genotypes imposed stronger facilitative effects, despite being much smaller under stress, probably because they retrieved more salt from the soil. Stress tolerance defined facilitative effect and response via distinct mechanisms. We advocate more controlled experiments with model species to advance our understanding of the trait dependence of biotic interactions and their consequences for community organization.

In forest succession, the ecological strategies of the dominant species that are based on functional traits are important in the determination of both the mechanisms and the potential directions of succession. Thirty-one plots were established in the Loess Plateau region of northern Shaanxi in China. Fifteen leaf traits were measured for the 31 dominant species that represented the six stages of succession, and the traits included four that were related to morphology, seven to stoichiometry and four to physiological ecology. The species from the different successional stages had different patterns of distribution of the traits, and different key traits predicted the turnover of the species during succession. The ash and the cellulose contents were key regulatory factors of species turnover in the early successional communities, and the trait niche forces in sugar and leaf dry mass content might become more important with the progression of succession. When only the three herb stages were considered, a progressive replacement of the ruderal by the competitive-ruderal species occurred in the intermediate stages of succession, which was followed by the stress-tolerant-competitive or the competitive-stress tolerant-ruderal strategists late in the succession. Thus, the different species that occurred in the different stages of succession shared different trait-based ecological strategies. Additionally, these differences occurred concomitantly with a shift toward competitive-stress tolerant-ruderal strategies.

Toxicity of engineered nanoparticles on organisms is of concern worldwide due to their extensive use and unique properties. The impacts of ZnO nanoparticles (ZnO NPs) on seed germination and root elongation of corn (Zea mays L.) and cucumber (Cucumis sativus L.) were investigated in this study. The role of seed coats of corn in the mitigation toxicity of nanoparticles was also evaluated. ZnO NPs (1,000 mg L(-1)) reduced root length of corn and cucumber by 17 % (p0.05) and 51 % (p0.05), respectively, but exhibited no effects on germination. In comparison with Zn(2+), toxicity of ZnO NPs on the root elongation of corn could be attributed to the nanoparticulate ZnO, while released Zn ion from ZnO could solely contribute to the inhibition of root elongation of cucumber. Zn uptake in corn exposed to ZnO NPs during germination was much higher than that in corn exposed to Zn(2+), whereas Zn uptake in cucumber was significantly correlated with soluble Zn in suspension. It could be inferred that Zn was taken up by corn and cucumber mainly in the form of ZnO NPs and soluble Zn, respectively. Transmission electron microscope confirmed the uptake of ZnO NPs into root of corn. Although isolation of the seed coats might not be the principal factor that achieved avoidance from toxicity on germination, seed coats of corn were found to mitigate the toxicity of ZnO NPs on root elongation and prevent approximately half of the Zn from entering into root and endosperm.

The rapid development of high-throughput technologies enables researchers to sequence the whole metagenome of a microbial community sampled directly from the environment. The assignment of these sequence reads into different species or taxonomical classes is a crucial step for metagenomic analysis, which is referred to as binning of metagenomic data. Most traditional binning methods rely on known reference genomes for accurate assignment of the sequence reads, therefore cannot classify reads from unknown species without the help of close references. To overcome this drawback, unsupervised learning based approaches have been proposed, which need not any known species’ reference genome for help. In this paper, we introduce a novel unsupervised method called MCluster for binning metagenomic sequences. This method uses N-grams to extract sequence features and utilizes automatic feature weighting to improve the performance of the basic K-means clustering algorithm. We evaluate MCluster on a variety of simulated data sets and a real data set, and compare it with three latest binning methods: AbundanceBin, MetaCluster 3.0, and MetaCluster 5.0. Experimental results show that MCluster achieves obviously better overall performance ( $F$ -measure) than AbundanceBin and MetaCluster 3.0 on long metagenomic reads ( $\ge$ 800 bp); while compared with MetaCluster 5.0, MCluster obtains a larger sensitivity, and a comparable yet more stable $F$ -measure on short metagenomic reads ( ${ bp). This suggests that MCluster can serve as a promising tool for effectively binning metagenomic sequences.

The potential of a hybrid process incorporating sulfur-based bioleaching and sulfide-based precipitation for treatment of metal-contaminated soil was examined in batch-type experiments. The sulfur-based soil bioleaching process with Acidithiobacillus sp. could be initiated at a wide range of initial pH from 4.0 to 6.3. After 15 days, 98% of Zn, 89% of Cu and 79% of Cd was bioleached. The gaseous sulfides recycling from Desulfovibrio sp.-mediated sulfate-reducing reactor via N2 sparging efficiently treated metal-loaded soil leachate. With a sulfide/metal ratio of 3.0, 88% of Zn, 100% of Cu and 95% of Cd were precipitated, resulting in effluent metal concentrations of 3.5 mg Zn2+/L, 0.2 mg Cu2+/L and 0.03 mg Cd2+/L. Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the supplemental file.

Quantifying the drivers underlying the distribution of biodiversity during succession is a critical issue in ecology and conservation and also can provide insights into the mechanisms of community assembly. Ninety plots were established in the Loess Plateau region of northern Shaanxi in China. The taxonomic and phylogenetic (alpha and beta) diversity were quantified within six succession stages. Null models were used to test whether phylogenetic distance observed differed from random expectations. Taxonomic beta diversity did not show a regular pattern, while phylogenetic beta diversity decreased throughout succession. The shrub stage occurred as a transition from phylogenetic overdispersion to clustering either for NRI (Net Relatedness Index) or betaNRI. The betaNTI (Nearest Taxon Index) values for early stages were on average phylogenetically random, but for the betaNRI analyses, these stages were phylogenetically overdispersed. Assembly of woody plants differed from that of herbaceous plants during late community succession. We suggest that deterministic and stochastic processes respectively play a role in different aspects of community phylogenetic structure for early succession stage and that community composition of late succession stage is governed by a deterministic process. In conclusion, the long-lasting evolutionary imprints on the present-day composition of communities arrayed along the succession gradient.

A bench-scale, stirred-tank batch precipitator was used to assess the selective removal of Cu2+, Zn2+, Ni2+ and Fe2+ from acidic electroplating wastewater using sulphide from a sulphidogenic bioreactor effluent. At pH approximately 1.7,99% of Cu was selectively precipitated, over Zn, Ni and Fe, from the wastewater as pure CuS by recycling H2S from the bioreactor effluent via N2 sparging, resulting in a Cu effluent concentration0.4 mg/L. The rate of Cu precipitation increased from 1.6 to 6.4 mg Cu/(L x min) when the pH of the bioreactor effluent decreased from 7.5 to 5.5. Experiments focusing on the precipitation of Zn, Ni and Fe from the wastewater devoid of Cu (at pH approximately 1.7), using sulphide-rich bioreactor effluent, achieved approximately 85-97% precipitation efficiency for Zn, approximately 25-92% for Ni, and approximately 2-99% for Fe, depending on the initial sulphide/metal molar ratio. The sulphide/metal ratio of 1.76 was found to be optimal for the precipitation of Zn, Ni and Fe with sulphides and, to a lesser extent, with hydroxides, resulting in residual metal concentrations of 1 mg Zn/L, 3 mg Ni/L, and 0.5 mg Fe/L. These findings suggest the potential of waste biogenic sulphides for the selective recovery of valuable metals from acidic metal-rich industrial wastewaters.

The transport behavior of titanium dioxide nanoparticles (TiO2 NPs, 30 nm in diameter) was studied in well-defined porous media composed of clean quartz sand over a range of solution chemistry under acidic conditions. Transport of TiO2 NPs was dramatically enhanced by humic substances (HS) at acidic pH (4.0, 5.0 and 6.0), even at a low HS concentration of 0.5 mg L−1. Facilitated transport of TiO2 NPs was likely attributable to the increased stability of TiO2 NPs and repulsive interaction between TiO2 NPs and quartz sands due to the adsorbed HS. The mobility of TiO2 NPs was also increased with increasing pH from 4.0 to 6.0. Although transport of TiO2 NPs was insensitive to low ionic strength, it was significantly inhibited by high concentrations of NaCl and CaCl2. In addition, calculated Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction energy indicated that high energy barriers were responsible for the high mobility of TiO2 NPs, while the secondary energy minimum could play an important role in the retention of TiO2 NPs at 100 mmol L−1 NaCl. Straining and gravitational settlement of larger TiO2 NPs aggregates at 1 mg L−1 HS, pH 5.0, and 2 mmol L−1 CaCl2 could be responsible for the significant retention even in the presence of high energy barriers. Moreover, more favorable interaction between approaching TiO2 NPs and TiO2 NPs that had been already deposited on the collector resulted in a ripening-shape breakthrough curve at 2 mmol L−1 CaCl2. Overall, a combination of mechanisms including DLVO-type force, straining, and physical filtration was involved in the retention of TiO2 NPs over the range of solution chemistry examined in this study.

Nucleosome positioning plays an essential role in cellular processes by modulating accessibility of DNA to proteins. Many computational models have been developed to predict genome-wide nucleosome positions from DNA sequences. Comparative analysis of predicted and experimental nucleosome positioning maps facilitates understanding the regulatory mechanisms of transcription and DNA replication. Therefore, a comprehensive evaluation of existing computational methods is important and useful for biologists to choose appropriate ones in their research. In this article, we carried out a performance comparison among eight widely used computational methods on four species including yeast, fruitfly, mouse and human. In particular, we compared these methods on different regions of each species such as gene sequences, promoters and 5 0 UTR exons. The experimental results show that the performances of the two latest versions of the thermodynamic model are relatively steadier than the other four methods. Moreover, these methods are workable on four species, but their performances decrease gradually from yeast to human, indicating that the fundamental mechanism of nucleosome positioning is conserved through the evolution process, but more and more factors participate in the determination of nucleosome positions, which leads to sophisticated regulation mechanisms.

Method names play an important role in software maintenance. A good name explains the function of a method to developers, while bad names mislead them. However, method naming is a complicated task. For example, Java programming specification suggests that method names should be verbs or verb phrases. Previous research shows that each identical verb is related to at least one name rule and each rule is consists of 30 conditions. Since large-scale software contains hundreds of identical verbs, choosing the proper verb for a method is related to thousands of conditions. There exists some semi-automated method verb rule mining techniques. these rules are useful to find if a method uses the wrong verb. However, they are not effective for general case when no rules are applicable. In addition, none of them discusses how to find the proper target of the verb. This paper proposes an automated method-naming tool, based on machine learning approach. Experiments on Eclipse and other Java projects show that our tool can successfully predict the verbs of 70% methods and pick out the proper targets in method contents for 90% methods.

A hybrid process combining solubilization via sulfuric acid produced by sulfur-oxidizing bacteria with precipitation via sulfide produced by sulfate-reducing bacteria was investigated to isolate soil-borne metal contaminants as purified metal-sulfides. The highly efficient two-step acidification process involved bioproduction of sulfuric acid in a culture medium containing 30% (v/v) of sludge filtrate (SF). Soil was added to the culture after maximum acid production. Solubilization efficiencies of 95% for Zn, 76% for Cu and 97% for Cd were achieved after 16 days. At pH 1.9, 3.0 and 4.0, 99% of Cu2+, 96% of Cd3+ and 93% of Zn2+, respectively, were precipitated from the soil leachate by sulfide transported from sulfidogenic bioreactor via N2 sparging, resulting in final effluent metal contents at the ppb-level. The introduction of SF did not affect the precipitation kinetics and purity of the recovered precipitates. Ultimately, 75% of Cu and 86% of Zn were recovered from the soil as pure CuS and ZnS (confirmed by SEM–EDS and XRD). These results demonstrate the potential of the integrated method for the selective production of valuable metals from metal contamination in soils.

A synthetic mildly acidic wastewater containing 47.1 mg Zn2+/L, 19.8 mg Cu2+/L, 5.0 mg Cr3+/L, and 4.0 g SO42-/L was treated using a sulfate-reducing bioreactor. A laboratory-scale continuous-flow stirred tank reactor was applied. The results showed that the sodium lactate-supplemented sulfate-reducing process resulted in the effluent pH increase from ~5.0 to ~8.0, nearly complete sulfate reduction, and metal removal efficiencies greater than 99% for Zn and Cu, and >;89% for Cr, respectively. Changing the concentration of sodium lactate from 17 to 4.0 g/L (i.e. the decrease of chemical oxygen demand (COD)/SO42- ratio from 3.0 to 0.78) decreased greatly the percentage of sulfate reduction from ~100 to ~15%, but had no adverse influence on the final efficiencies of metals removal. The ability of this process to effectively remove sulfate and heavy metals makes it particularly attractive for the treatment of these contaminated aqueous streams similar to acid mine drainage.

A linked microbial process comprising bioleaching with sulfate-oxidizing bacteria and bioprecipitation with sulfate-reducing bacteria operating sequentially was investigated to deeply remove contaminating metals from dredged sediment. The results showed that sediment bioleaching resulted in a sharp decrease in sediment pH from an initial pH ∼7.6 to pH ∼2.5 within 10–20 days, approximately 65% of the main heavy metals present (Zn + Cu + Cr) were solubilized, and most of the unsolubilized metals existed in residual form of sediment. The acidic leachate that resulted from sediment bioleaching was efficiently stripped of metal sulfates using a bioprecipitation reactor when challenged with influent as low as pH ∼3.7. More than 99% of Zn 2+ , 99% of Cu 2+ and 90% of Cr 3+ were removed from the leachate, respectively, due to the formation of ZnS, Cu 2 S and CrOOH precipitates, as confirmed by SEM-EDS and XRD detection. It was also found that alkalization of bioleached sediment using Ca(OH) 2 excluded the risk of sediment re-acidification. The ability of the combined process developed in this study to deeply remove heavy metals in insoluble sulfides or hydroxides forms makes it particularly attractive for the treatment of different types of metal contaminants.