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The intertidal zone—a transitional boundary between terrestrial and marine environments—has important ecological functions, and receives polycyclic aromatic hydrocarbons (PAHs) from human activities, but how and to what extent anthropogenic factors influence the distribution of PAHs in this important niche remain largely unknown. Here we measured the distribution of United States Environmental Protection Agency priority PAHs in samples of intertidal sediments from across more than 4,500 km of China’s coastline. The total PAH concentrations ranged from 2.3 to 1,031.7 ng g−1 sediment (dry weight) and all PAHs showed positive correlations with total organic carbon (TOC). TOC-normalized high-molecular-weight (HMW) PAH concentrations, but not TOC-normalized low-molecular-weight (LMW) PAHs, were positively correlated with TOC. Moreover, population size and economic development influenced TOC-normalized HMW PAH concentrations, whereas urbanization had a major influence on TOC-normalized LMW PAHs. Human activities also indirectly influenced TOC-normalized PAH concentrations by affecting TOC. In sum, our investigation provides continental-scale evidence that human activities have key and differential effects on the distribution and deposition of PAHs in intertidal sediments, and shows that pollution status and profile of PAHs can be used to index regional industrialization and urbanization status. Little is known about how human factors influence the patterns of polycyclic aromatic hydrocarbons (PAHs) in the intertidal zone, a transitional boundary between terrestrial and marine environments. This study shows that human activities affect both the distribution and the deposition of PAHs.

Pore structure characteristics of ultra-low permeability reservoirs are studied in this paper. The impact of pore structure characteristics on permeability and reservoir development effect is analyzed by conventional and constant-rate mercury penetration experiments. The results show that the frequency curve of pore radius distribution of ultra-low permeability reservoirs has little change with permeability. The average pore radius in ultra-low permeability reservoirs with different permeability levels had little difference, and its distribution ranges from 98.5 to 110.1 μm. With decrease of permeability, the frequency distribution curves of throat radius and pore-throat ratio change significantly. The peak value of throat radius curve moves to the left and increases significantly, and the average throat-radius distribution decreases from 2.33 to 0.91 μm. However, the impact of pore-throat ratio on permeability is contrary to that of throat radius. Both throat radius and pore-throat ratio has strong correlation with permeability, and they are in exponential relationship. With the in-depth study, it is found that seepage capacity of reservoirs is restricted mainly by throat radius and pore-throat ratio. When throat radius decreases to less than 1 μm and pore-throat ratio increases more than 130, permeability decreases sharply and obviously. When permeability is less than 2 × 10−3μm2, the proportion of fine throats and medium throats under the condition of effective water injection is significantly lower, and the production of single well and the recovery efficiency by water flooding in ultra-low permeability reservoirs are low. The study explains effectively the fundamental reason for the poor efficiency of production and recovery of ultra-low permeability reservoirs from the mechanism.

The purposes of this study were to analyse the spatiotemporal variations in greenhouse gas diffusive fluxes at the sediment–water interface of sewage-draining rivers and natural rivers, and investigate the factors responsible for the changes in greenhouse gas diffusive fluxes. Greenhouse gas diffusive fluxes at the sediment–water interface of rivers in Tianjin city (Haihe watershed) were investigated during July and October 2014, and January and April 2015 by laboratory incubation experiments. The influence of environmental variables on greenhouse gas diffusive fluxes was evaluated by Spearman’s correlation analysis and a multiple stepwise regression analysis. Sewage-draining rivers were more seriously polluted by human sewage discharge than natural rivers. The greenhouse gas diffusive fluxes at the sediment–water interface exhibited obvious spatiotemporal variations. The mean absolute value of the CO2 diffusive fluxes was seasonally variable with spring>winter>fall>summer, while the mean absolute values of the CH4 and N2O diffusive fluxes were both higher in summer and winter, and lower in fall and spring. The annual mean values of the CO2, CH4 and N2O diffusive fluxes at the sewage-draining river sediment–water interface were − 123.26 ± 233.78 μmol m−2 h−1, 1.88 ± 6.89 μmol m−2 h−1 and 1505.03 ± 2388.46 nmol m−2 h−1, respectively, which were 1.22, 4.37 and 134.50 times those at the natural river sediment–water interface, respectively. The spatial variation of the N2O diffusive fluxes in the sewage-draining rivers and the natural rivers was the most significant. As a general rule, the more serious the river pollution was, the greater the diffusive fluxes of the greenhouse gases were. On average for the whole year, the river sediment was the sink of CO2 and the source of CH4 and N2O. There were positive correlations among the CO2, CH4 and N2O diffusive fluxes. The main influencing factor for CO2 and N2O diffusive fluxes was the water temperature of the overlying water; however, the key factors for CH4 diffusive fluxes were the Eh of the sediment and the NH4+-N of the overlying water. River sediment can be either a sink or a source of greenhouse gases, which varies in different levels of pollution and different seasons. Human sewage discharge has greatly affected the carbon and nitrogen cycling of urban rivers.

Light alkenes are the key building blocks in chemical industry. Dehydrogenation of light alkanes to light olefins offers an important route for the value-added utilization of alkanes and the diversification in olefin supplies. Featured with the free coking and no thermodynamic restriction, oxidative dehydrogenation of alkanes to olefins has attracted much attention. The early reported metal oxide catalysts usually have good activities, but tend to deeply oxidize olefins to CO2, leading to poor yield of olefin products. Later on, metal-free catalysts start to catch the eye. As a new estabilished catalytic system, metal-free boron-based catalysts show distinctive reaction characteristics of the high selectivity of olefins and the inhibition of deep oxidation reactions, as compared to metal-based catalysts. Hexagonal boron nitride ( h -BN) was first proved to be a highly active catalyst in the oxidative dehydrogenation reaction. Afterwards, some borides (e.g., SiB6, CB4) and supported boron catalysts have also been reported. The boron-based catalysts exhibit high activities and selevtivities to olefins with negligible formations of CO2, which provides a new sight in the selective cleavage of C–H bonds. In the combination of spectroscopic and kinetic analysis, the BO x species on the catalyst surface was determined as the active sites. The unique catalysis of boron-based catalysts updates the traditional perception on the alkane activation and has becoming a new hotspot worldwide. Besides, other metal-free catalysts, nanostructured carbon-based materials including carbon nanotubes, carbon nanofibers and nano-diamonds have also been shown a great potential in the dehydrogenation of light alkanes. The carbonyl/quinone groups are verified to be the active sites for dehydrogenation of light alkanes; the carboxyl, carboxylic anhydride and lactone groups could act as deep oxidative sites and cause the reduction of olefin selectivity. Moreover, doping of heteroatoms (B, P and N) into carbon matrix is effective for the improvement of olefin selectivity. This review timely highlights the recent developments of metal-free catalysts in the oxidative dehydrogenation of light alkanes, particulary focusing on the newly established boron-based catalytic system. At the end, we propose the perspective research directions of the dehydrogenation of light alkanes.

This work concerned the oxo exchange of americyl(VI) ([AmO2]2+) in alkaline solution by means of B3LYP calculations. Four possible reaction pathways were investigated and compared, which covered the direct intramolecular proton transfer pathway (Path 1 and 2), the pathway via a T-shape [AmO3](aq) intermediate (Path 3), and the binuclear pathway (Path 4). The Path 3 was predicted as the most probable pathway in view of the energetics, the activation energy (∆G≠) to which was calculated to be 55.7 kJ/mol. The evolution of the Mayer bond order of key bonds were analyzed to assist the understanding of the mechanism.

The functionalization of CO2 mediated by a series of U(IV) mixed-sandwich compounds, (COTTIPS2)Cp*UR (R = −CH3, −CH2Ph, −CH2TMS, −CH(TMS)2, −NHPh, −OPh, −SPh, −SePh; COTTIPS2 = C8H6(SiiPr3-1,4)2; C...

While nitrogen (N2) fixation is an important process in nitrogen (N) biogeochemical cycling, supplying a significant portion of the N in natural ecosystems, few quantitative constraints exist concerning its contribution to the N enrichment and export from river ecosystems. This study estimates the N2 fixation rates of urban rivers in the Yangtze Estuary area using acetylene reduction. The results demonstrate that the prominent spatiotemporal variability of river N2 fixation rates is driven by various environmental factors. River N2 fixation rates are significantly higher in the summer (90.57 ± 14.60 ngN·L−1·h−1) than in the winter (57.98 ± 15.73 ngN·L−1·h−1). Spatially, rivers draining urban and suburban areas have higher N2 fixation rates than those draining rural areas. The N2 fixation rates are positively correlated with the N2 fixing cyanobacteria density, water temperature, light, and the water phosphorus (P) concentration, but they are negatively correlated with the dissolved N concentration (NH4+-N and NO3−-N). The N2 fixation rates annually range from 53.20 to 89.24 ngN·L−1·h−1 for all of the sampling rivers, which is equivalent to a depth integrated (0–0.6 m) N input of 0.163–0.274 gN·m−2·a−1. The determined annual N input via N2 fixation is generally higher than that of marine systems, but it is lower than that of eutrophic lakes. This study provides robust evidence that N2 fixation can supply a substantial portion of the N input to human-impacted river ecosystems, which has not been sufficiently accounted for when determining the N mass balance of riverine ecosystems. A high N2 fixation rate may increase the ratio of N to P input to river systems, and therefore render P the limiting factor in aquatic eutrophication.

Almost all of the aerobic granular sludge (AGS) reactors were fed on certain amounts of Ca

For the geological repository of high-level radioactive waste (HLW) built in granitic host rock，the control of buffer material (compacted bentonite) erosion and subsequent loss caused by groundwater in granite fissures is an unresolved problem of major concern. We propose here new insight into enhancing the erosion resistance of compacted bentonite by means of its electrostatic interaction with oppositely-charged layered double hydroxide (LDH). The interaction between bentonite and LDH was studied by dropwise addition of colloidal LDH into colloidal bentonite suspension, during which the variation in electrical conductivity, zeta potential and particle size proved a strong interaction between these two materials. Interestingly, in addition to their aggregation, intercalated structures of LDH and montmorillonite were found in the composite (BEN@LDH) by a combined characterization of X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM), and were confirmed by density functional theory (DFT) calculation. Colloid generation of compacted BEN@LDH under ultrasonic conditions is negligible comparing with that of compacted bentonite, indicating a significantly higher erosion resistance. Besides, a small amount of LDH by mechanically mixing with bentonite (mass ratio 1:99) can also effectively improve the erosion resistance of compacted bentonite. Moreover, BEN@LDH displayed stronger retention performance towards U(VI) and Se(IV) than bentonite under near-neutral/weakly alkaline conditions. Our results indicate that LDH is a promising additive in compacted bentonite, and this approach may be extended to common geotechnical structures built with clays and soils.

Polyphosphate (polyP) accumulating organisms (PAOs) are the key agent to perform enhanced biological phosphorus removal (EBPR) activity, and intracellular polyP plays a key role in this process. Potential associations between EBPR performance and the polyP structure have been suggested, but are yet to be extensively investigated, mainly due to the lack of established methods for polyP characterization in the EBPR system. In this study, we explored and demonstrated that single-cell Raman spectroscopy (SCRS) can be employed for characterizing intracellular polyPs of PAOs in complex environmental samples such as EBPR systems. The results, for the first time, revealed distinct distribution patterns of polyP length (as Raman peak position) in PAOs in lab-scale EBPR reactors that were dominated with different PAO types, as well as among different full-scale EBPR systems with varying configurations. Furthermore, SCRS revealed distinctive polyP composition/features among PAO phenotypic sub-groups, which are likely associated with phylogenetic and/or phenotypic diversity in EBPR communities, highlighting the possible resolving power of SCRS at the microdiversity level. To validate the observed polyP length variations via SCRS, we also performed and compared bulk polyP length characteristics in EBPR biomass using conventional polyacrylamide gel electrophoresis (PAGE) and solution 31P nuclear magnetic resonance (31P-NMR) methods. The results are consistent with the SCRS findings and confirmed the variations in the polyP lengths among different EBPR systems. Compared to conventional methods, SCRS exhibited advantages as compared to conventional methods, including the ability to characterize in situ the intracellular polyPs at subcellular resolution in a label-free and non-destructive way, and the capability to capture subtle and detailed biochemical fingerprints of cells for phenotypic classification. SCRS also has recognized limitations in comparison with 31P-NMR and PAGE, such as the inability to quantitatively detect the average polyP chain length and its distribution. The results provided initial evidence for the potential of SCRS-enabled polyP characterization as an alternative and complementary microbial community phenotyping method to facilitate the phenotype-function (performance) relationship deduction in EBPR systems.

Boron-based catalysts show excellent performance in oxidative dehydrogenation (ODH) of light alkanes to alkenes with high selectivity and extremely good antioxidation properties. However, the anti-deep-oxidation mechanism remains unclear. Herein, we chose h-BN and B2O3 as representative boron-based catalysts to investigate their reactions with two important intermediates in the light alkane ODH, Et· (evolving to ethene) and EtO· (evolving to ethene or COx), to elucidate the origin of the antioxidation of alkanes. The density functional theory calculations reveal that surface boron sites could eliminate alkoxy in their vicinity, resulting in exceptional inhibition of alkane deep-oxidation. The analysis of the electronic and geometric structures of key stationary points showed that the oxophilicity of B determined the low deep-oxidation of alkanes, and the homoleptic coordination of B with all three ligating atoms being O moderately enhanced its oxophilicity. This work represents a novel conceptual advance in the mechanistic understanding of alkane ODH.

Bioretention has been considered as an effective management practice for urban stormwater in the removal of pollutants including polycyclic aromatic hydrocarbons (PAHs). However, the accumulation of high-molecular-weight (HMW) PAHs in bioretention systems and their potential impact on the pollutants removal performance and microbial ecology are still not fully understood. In this study, comparisons of treatment effectiveness, enzyme activity and microbial community in bioretention systems with different types of media amendments were carried out at different spiking levels of pyrene (PYR). The results showed that the removal efficiencies of chemical oxygen demand (COD) and total nitrogen in the bioretention systems were negatively impacted by the PYR levels. The relative activities of soil dehydrogenase and urease were increasingly inhibited by the elevated PYR level, indicating the declining microbial activity regarding organic matter decomposition. The spiking of PYR negatively affected microbial diversity, and distinct time- and influent-dependent changes in microbial communities were observed. The relative abundance of PAH-degrading microorganisms increased in PYR-spiked systems, while the abundance of nitrifiers decreased. The addition of media amendments was beneficial for the enrichment of microorganisms that are more resistant to PYR-related stress, therefore elevating the COD concentration removal rate by ∼50%. This study gives new insight into the multifaceted impacts of HMW PAH accumulation on microbial fingerprinting and enzyme activities, which may provide guidance on better stormwater management practices via bioretention in terms of improved system longevity and performance.

Polycyclic aromatic hydrocarbons (PAHs) are key organic pollutants in the environment that pose threats to the ecosystem and human health. The degradation of high molecular weight (HMW) PAHs by enriched bacterial consortia has been previously studied, while the involved metabolisms and microbial communities are still unclear and warrant further investigations. In this study, five bacterial consortia capable of utilizing different PAHs (naphthalene, anthracene, and pyrene) as the sole carbon and energy sources were enriched from PAH-contaminated soil samples. Among the five consortia, consortium TC exhibited the highest pyrene degradation efficiency (91%) after 19 d of incubation. The degradation efficiency was further enhanced up to 99% by supplementing yeast extract. Besides, consortium TC showed tolerances to high concentrations of pyrene (up to 1000 mg/L) and different heavy metal stresses (including Zn2+, Cd2+, and Pb2+). The dominant genus in consortium TC, GS, and PL showing relatively higher degradation efficiency for anthracene and pyrene was Pseudomonas, whereas consortium PG and GD were predominated by genus Achromobacter and class Enterobacteriaceae, respectively. Consortium TC, as a highly efficient HMW PAH-degrading consortium, could be applied for synergistic biodegradation of HMW PAHs and in situ bioremediation of the sites contaminated with both PAHs and heavy metals.

The identification of protein–ligand interaction plays a key role in biochemical research and drug discovery. Although deep learning has recently shown great promise in discovering new drugs, there remains a gap between deep learning-based and experimental approaches. Here, we propose a novel framework, named AIMEE, integrating AI model and enzymological experiments, to identify inhibitors against 3CL protease of SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2), which has taken a significant toll on people across the globe. From a bioactive chemical library, we have conducted two rounds of experiments and identified six novel inhibitors with a hit rate of 29.41%, and four of them showed an IC50 value

Rivers and streams contribute significant quantities of methane (CH

Aiming at analyzing the temporal structures in evolutionary networks, we propose a community detection algorithm based on graph representation learning. The proposed algorithm employs a Laplacian matrix to obtain the node relationship information of the directly connected edges of the network structure at the previous time slice, the deep sparse autoencoder learns to represent the network structure under the current time slice, and the K-means clustering algorithm is used to partition the low-dimensional feature matrix of the network structure under the current time slice into communities. Experiments on three real datasets show that the proposed algorithm outperformed the baselines regarding effectiveness and feasibility.

Sidestream EBPR (S2EBPR) is an emerging alternative process to address common challenges in EBPR related to weak wastewater influent and may improve EBPR process stability. A systematic evaluation and comparison of the process performance and microbial community structure was conducted between conventional and S2EBPR facilities in North America. The statistical analysis suggested higher performance stability in S2EBPR than conventional EBPR, although possible bias associated with other plant-specific factors might have affected the comparison. Variations in stoichiometric values related to EBPR activity and discrepancies between the observed values and current model predictions suggested a varying degree of metabolic versatility of PAOs in S2EBPR systems that warrant further investigation. Microbial community analysis using various techniques suggested comparable known candidate PAO relative abundances in S2EBPR and conventional EBPR systems, whereas the relative abundance of known candidate GAOs seemed to be consistently lower in S2EBPR facilities than conventional EBPR facilities. 16S rRNA gene sequencing analysis revealed differences in the community phylogenetic fingerprints between S2EBPR and conventional facilities and indicated statistically higher microbial diversity index values in S2EBPR facilities than those in conventional EBPRs. PRACTITIONER POINTS: Sidestream EBPR (S2EBPR) can be implemented with varying and flexible configurations, and they offer advantages over conventional configurations for addressing the common challenges in EBPR related to weak wastewater influent and may improve EBPR process stability. Survey of S2EBPR plants in North America suggested statistically more stable phosphorus removal performance in S2EBPR plants than conventional EBPRs, although possible bias might affect the comparison due to other plant-specific factors. The EBPR kinetics and stoichiometry of the S2EBPR facilities seemed to vary and are associated with metabolic versatility of PAOs in S2EBPR systems that warrant further investigation. The abundance of known candidate PAOs in S2EBPR plants was similar to those in conventional EBPRs, and the abundance of known candidate GAOs was generally lower in S2EBPR than conventional EBPR facilities. Further finer-resolution analysis of PAOs and GAOs, as well as identification of other unknown PAOs and GAOs, is needed. Microbial diversity is higher in S2EBPR facilities compared with conventional ones, implying that S2EBPR microbial communities could show better resilience to perturbations due to potential functional redundancy.

Oxidative dehydrogenation (ODH) of light alkanes catalyzed by metal oxides is considered to be a thermodynamically favorable process for olefin production. The strong interaction between the unoccu...

Molecular dynamics (MD) simulations were performed to investigate the influence of curvature and backbone rigidity of an oxygenated surface, here graphene oxide (GO), on its adsorption of uranyl in collaboration with humic acid (HA). The planar curvature of GO was found to be beneficial in impeding the folding of HA. This, together with its rigidity that helps stabilize the extended conformation of HA, offered rich binding sites to interact with uranyl with only marginal loss of binding strength. According to our simulations, the interaction between uranyl and GO was mainly driven by electrostatic interactions. The presence of HA not only provided multiple sites to compete/cooperate with GO for adsorption of free uranyl but also interacted with GO acting as a "bridge" to connect uranyl and GO. The potential of mean force (PMF) profiles implied that HA significantly enhanced the interaction strength between uranyl and GO and stabilized the uranyl-GO complex. Meanwhile, GO could reduce the diffusion coefficients of uranyl and HA and retard their migrations in aqueous solution. This work provides theoretical hints on the GO-based remediation strategies for the sites contaminated by uranium or other heavy metal ions and oxygenated organic pollutants.

In this paper, the influence of humic acid (HA) and fulvic acid (FA) on biomineralization behaviour was evaluated. The results showed HA and FA did not obviously inhabit or promote the precipitation of U-phosphate minerals. The data from molecular dynamic simulation indicated that the free energy for the dissociation of uranyl the PO43− -uranyl was 202.49 kJ/mol, which was much larger than that form HA-uranyl (88.3 kJ/mol). These simulated results revealed the less competitiveness of HA and FA with PO43− for uranyl and explained why HA and FA had less impacted on the formation of U-phosphate minerals. However, the influence of HA/FA on the morphology was obvious, the microstructure of the bio-minerals changed from small particles to lamellar stacking structure with the addition of HA or FA. The findings of this study are helpful for us to gain a better understanding natural U-phosphate biomineralization behaviour.

The nine-membered ring-bearing bicyclo[5.2.2]tetrahydrooxonines frameworks have enantioselectively been constructed via a tandem [3 + 2] cycloaddition/Cope rearrangement reaction of vinylethylene carbonates (VECs) with coumalates or pyrones. Under mild conditions, palladium-catalyzed asymmetric tandem reaction of various substituted VECs and coumalates or pyrones proceeds smoothly to produce the corresponding medium-sized heterocyclic compounds in high yields with very high enantioselectivities. Moreover, the reaction on the gram scale and further diverse transformations of the products were workable. The reaction mechanism was investigated through control experiments and DFT calculations, which show the reaction proceeds via a tandem [3 + 2] cycloaddition/Cope rearrangement pathway rather than via a [5 + 4] cycloaddition pathway.

Aims: Stratification of the risk of malignant arrhythmias in patients with coronary artery disease remains a challenge. This study evaluated the potential of high voltage J-waves in patients with acute ST-segment elevated myocardial infarction (STEMI) to predict the risk of malignant arrhythmias during hospitalization. Methods: A total of 128 consecutive STEMI patients with J-waves were enrolled within 48 h after the onset of the STEMI in this prospective study. The mean age was 62.97 ± 12.1 years, and 108 patients were male. Both 12-lead electrocardiograms (ECGs) and right-sided chest lead ECGs were recorded simultaneously within 10 min of admission to the hospital. Continuous ECG monitoring was administered from admission until discharge. Clinical characteristics and ECG parameters were compared between patients who survived and those who died during hospitalization. Results: Malignant ventricular arrhythmias (MVAs) were seen with J-waves more frequently in STEMI patients who subsequently died (P < 0.05). J-wave voltage, QTDc, Tp-e, and the Tp-e/QT ratio increased significantly in patients who died (P < 0.05). Multivariate logistic regression analysis revealed that J-wave voltage (odds ratio [OR], 89.09; 95% confidence interval [CI], 2.606-3045.108; P < 0.05) and MVAs (OR, 4.296; 95% CI, 1.348–13.693; P < 0.05) were associated with the occurrence of sudden death in patients with STEMI during hospitalization. Conclusions: High voltage J-waves are a potential ECG parameter for predicting sudden death in patients with STEMI during hospitalization.

A new class of tantalum-based peroxocarbonate ionic liquid ([P4,4,4,4]3[Ta(η2-O2)3(CO4)]) has been generated through the reaction of pressurized CO2 with [P4,4,4,4]3[Ta(O)3(η2-O2)] in the presence of H2O2 during the reaction process. The newly formed species has been verified by NMR, FT-IR, HRMS and density functional theory (DFT) calculations. The CO2-induced monomeric peroxocarbonate anion-based ionic liquid is more advantageous than the monomeric peroxotantalate analogue for the epoxidation of olefins under very mild conditions. Interestingly, the transformation between peroxotantalate and peroxocarbonate species is completely reversible, and CO2 can actually act as a trigger agent for epoxidation reaction. The further mechanism studies by DFT calculation reveal that peroxo η2-O2 (site a) affords higher reactivity towards the CC bond than that of peroxocarbonate–CO4 (site b). These quantitative illustrations of the relationship between structural properties and kinetic consequences enable rational design for an efficient and environmental IL catalyst for the epoxidation of olefins.

Enterobactin (Ent) is a typical siderophore with strong iron affinity. Its dynamics in its intact form and holo state remains to be studied to understand its role in the in vivo behavior of metal ions and to facilitate its potential application in drug design and environmental remediation. Here, we report molecular dynamics simulations of both Ent enantiomers and their complexes with key actinides (Am3+, Cm3+, Th4+, U4+, Np4+ and Pu4+) to study the folding equilibria of Ent enantiomers and their binding affinity with actinides. For comparison, the ferric cation was also considered. In their neutral state, both enantiomers may exist in their folded and extended states in the aqueous phase with the former more stable owing to the favorable cation-π, π-π, and H-bond interactions. A helicity preference was observed in the folded states of Ent enantiomers, which was solidified when binding with Fe3+ while disrupted when binding with actinides. Upon binding with metal ions, the dynamics of Ent enantiomers exhibited dependence on the metal ions, and appeared to be more flexible in An3+/4+-Ent complexes than in Fe3+-Ent complexes. The conformational analysis and the energy decomposition of M3+/4+-Ent complexes indicated that their distinct conformational variations and dynamic fluxionality are enthalpy driven behaviors and dependent on the nature of the loaded metal ions. The Fe3+-Ent complexes had a more compact conformation, while the relatively loosely bound An3+/4+-Ent complexes allowed solvent water molecules to access the first coordination shell of An3+/4+ and weaken the interaction between An3+/4+ and Ent. This work is expected to enrich our knowledge of the folding equilibria of Ent enantiomers and their An3+/4+-Ent complexes, and contribute to communities that concern the in vivo and in vitro behaviors of Ent enantiomers and actinides.

In this manuscript, phosphine-dependent [3 + 3] and [4 + 3] annulation reactions of allenoate with aziridines were disclosed. The alkyldiphenylphosphine-promoted [4 + 3] annulation of allenoate with aziridines has been achieved under mild conditions, providing biologically interesting functionalized tetrahydroazepines in moderate to excellent yield with moderate to excellent regioselectivity and diastereoselectivity.

A DFT mechanistic study is undertaken on the functionalization of CO2 to form C-C, C-N, C-S, and C-O bonds promoted by trivalent uranium complexes (Tp*)(2)UR [Tp*=hydrotris(3,5-dimethylpyrazolyl)-borate ligand, R= -C equivalent to CPh (Cpda-CC), -C equivalent to CSiMe3 (Cpda-CSi), -NHPh (Cpda-N), -SPh (Cpda-S), and -OPh (Cpda-O)]. These model systems are similar in view of their two-step reaction mechanisms, that is, the insertion of CO2 into the U-E (E=C, N, O, S) bond to form a [U-kappa(1)-O2C] intermediate, followed by the reorientation of the carboxylate group to coordinate with the U atom in the kappa(2) manner (Cpdb-X, X=CC, CSi, N, S, O). However, the free energy barriers to the rate-determining steps are substantially different, increasing in the order Cpda-S

Inter-tidal wetlands at mangroves, salt marshes and sea grass bed are important carbon reservoirs that play a significant role in climate change mitigation. However, the lack of large-scale quantification and source identification of sediment organic carbon (SOC) in inter-tidal wetlands hampers the assessment of carbon storage potential in these systems. In this research, we hypothesized that SOC in the inter-tidal wetlands of Chinese East Coast were mainly from three potential sources (terrestrial soil, marine phytoplankton, local C3 and C4 plants as mangrove and salt marsh plants ). Based on elemental ratios and stable carbon isotope of core sediment from the inter-tidal wetlands along the east coast of China, we quantified the contribution of organic carbon (OC) sources and explored the hydrological and plant drivers controlling the variations of OC source contribution among different coastal environmental settings. We found SOC in the large estuaries (river runoff more than 50 billion m3/a) originated predominantly from terrestrial soil OC (46±9%), while the primary OC source of the smaller estuaries was marine phytoplankton OC (61±14%). These results suggested that the contribution of terrestrial soil OC increased with river runoff, whereas the share of marine phytoplankton OC decreased with runoff. Moreover, while mangroves played a substantial role in carbon storage at the southern part of the coast, our estimates revealed a sharp decline in the contribution of mangrove OC since the 1980s. These findings indicate carbon storage in the inter-tidal wetlands varies among contrasting coastal environmental conditions and among wetlands with different ages, providing implications for inter-tidal wetlands as an important carbon sink in the global carbon budget.

Coasts and estuaries are key contributors to atmospheric nitrous oxide (N2O) emissions. Here, we used laboratory incubation experiments to investigate temperature (12, 25, and 35 °C) and tidal effects on N2O fluxes in sediments sampled from three contrasting latitudinal subareas along the East China Coast (ECC) (North, Mid, and South). Overall, responses of N2O emissions to increasing temperature varied among the three climatic zones. During non-flood and flooding, mean N2O fluxes in sediments sampled from the North subarea increased exponentially with temperature (49.0 ±40.6 nmol m-2 h-1 at 12 °C to 3160 ±3960 nmol m-2 h-1 at 35 °C, and 741 ±518 nmol m-2 h-1 at 12 °C to 1020 ±1400 nmol m-2 h-1 at 35 °C, respectively). However, mean N2O fluxes in sediments sampled from the South subarea decreased at higher temperatures during flooding (977 ±306 nmol m-2 h-1 at 12 °C to 68.0 ±47.5 nmol m-2 h-1 at 35 °C) and non-flood (233 ±292 nmol m-2 h-1 at 12 °C to 183 ±142 nmol m-2 h-1 at 35 °C). Under ongoing global warming, intertidal areas at temperate may act as potential sources of N2O, whereas the contribution of low latitude coastal sediments to N2O budget may decrease. In addition, there is a combined impact of temperature and tidal fluctuation on N2O emissions that controls N2O production and consumption. Our results improve understanding of the diverse feedbacks of N2O emissions from coastal area to global climate change.

The enhanced biological phosphorus removal (EBPR) has been widely applied in treating domestic wastewater, while the performance on high-strength P wastewater is less investigated and the feasibility of coupling with short-cut nitrogen removal process remains unknown. This study first achieved the simultaneous high-efficient P removal and stable nitrite accumulation in one sequencing batch reactor for treating the synthetic digested manure wastewater. The average effluent P could be down to 0.8 ± 1.0 mg P/L and the P removal efficiency was 99.5 ± 0.8%. Candidatus Accumulibacter was the dominant polyphosphate accumulating organism (PAO) with the relative abundance of 14.2-33.1% in the reactor. Examination of the micro-diversity of Candidatus Accumulibacter using 16s rRNA gene-based oligotyping analysis revealed one unique Accumulibacter oligotype that different from the conventional system, which accounted for 64.2-87.9% of the total Accumulibacter abundance. The presence of high-abundant glycogen accumulating organisms (GAO) (15.6-40.3%, Defluviicoccus and Candidatus Competibacter) did not deteriorate the EBPR performance. Moreover, nitrite accumulation happened in the system with the effluent nitrite up to 20.4 ± 6.4 mg N/L and the nitrite accumulation ratio was nearly 100% maintained for 140 days (420 cycles). Nitrosomonas was the dominant ammonia-oxidizing bacteria with relative abundance of 0.3-2.4% while nitrite-oxidizing bacteria were almost undetected (

Nitrogen nutrient surplus is the main cause of a series of environmental problems in the Yangtze Estuary and its adjacent East China Sea (ECS). Denitrification plays an important role in controlling nitrate dynamics and fate in estuarine and coastal environments. We investigated the natural and potential rates of denitrification in the sediments of the Yangtze Estuary and ECS via slurry incubation experiments combined with acetylene inhibition techniques to reveal its contributions to total nitrogen reduction in this hypereutrophic continental shelf area. Key environmental factors, such as the sediment grain size, sediment extractable inorganic nitrogen (NH4+, NO3- and NO2-), sediment organic carbon (SOC), total nitrogen (TN), isotopic compositions (δ13C and δ15N), etc., were also investigated to determine the main factors controlling the denitrification processes. The measured rates of denitrification ranged from 0.39 to 28.49 ng N g-1·h-1. The total nitrogen removed by denitrification in the study area was 3.7 × 1010 g during August. In total, at least 3.3% of the external inorganic nitrogen transported annually into the estuary could be removed by the denitrification processes in the study area. The sediment denitrification rates correlated significantly with the extractable ammonium and δ15N values of surface sediments, indicating that coupled nitrification-denitrification processes may play an important role in nitrogen removal. Almost undetectable levels of nitrate in the sediment further revealed that nitrate supply, regardless of diffusion from the overlying water or production by sediment nitrification processes, is the bottleneck for denitrification.

Public-Private-Partnership (PPP) which allows private firms to finance projects for public sector infrastructure has been adopted as one of the most efficient procurement and delivery methods in mega construction projects recently. However, some problems, such as the allocation of excess revenue between public and private sectors are still found to be researched in order to get a sustainable development of PPP construction projects. Therefore, this paper developed a game model on the allocation of excess revenue between public and private parts based on the Cobb-Douglas project function; and meanwhile, two scenarios, namely priority strategy of private sector and priority strategy of public sector are considered respectively in this study. To be specific, firstly, this paper analyzed the emergence mechanism of game behavior between the two sectors. Secondly, priority strategy model of private sector and public sector were established and analyzed. Thirdly, Beijing Metro Line Four was taken as a numerical example to apply the model. Research results show that (1) both the revenue function of public sector and private sector are in positive correlation with the collaborative management capacity of PPP project (\( \beta \)); (2) the increase of investment of public sector contributes to more revenue of total excess revenue in PPP projects. The research outcomes are anticipated to deliver insights and guidance for successful and sustainable management of mega PPP projects.

Bisphenol A diglycidyl ether (BADGE)-based epoxy resin is one of the most widely used epoxy resins with an annual production amount of several million tons. Compared with all other legacy or emerging organic compounds, BADGE is special due to its toxicity and high reactivity in the environment. More and more studies are available on its analytical methods, occurrence, transformation and toxicity. Here, we provided a comprehensive review of the current BADGE-related studies, with focus on its production, application, available analytical methods, occurrences in the environment and human specimen, abiotic and biotic transformation, as well as the in vitro and in vivo toxicities. The available data show that BADGE and its derivatives are ubiquitous environmental chemicals and often well detected in human specimens. For their analysis, a water-free sample pretreatment should be considered to avoid hydrolysis. Additionally, their complex reactions with endogenous metabolites are areas of great interest. To date, the monitoring and further understanding of their transport and fate in the environment are still quite lacking, comparing with its analogues bisphenol A (BPA) and bisphenol S (BPS). In terms of toxicity, the summary of its current studies and Environmental Protection Agency (EPA) ToxCast toxicity database suggests BADGE might be an endocrine disruptor, though more detailed evidence is still needed to confirm this hypothesis in in vivo animal models. Future study of BADGE should focus on its metabolic transformation, reaction with protein and validation of its role as an endocrine disruptor. We believe that the elucidation of BADGEs can greatly enhance our understandings of those reactive compounds in the environment and human. National Environmental Agency (NEA) Published version This work was funded by Singapore National Environmental Agency (Grant No. 04SBS000714N025), the National Natural Science Foundation of China (Grant No. 52070156 and 31600421) and Visiting Researcher Fund Program of the State Key Laboratory of Eco-hydraulics in Northwest Arid Region, Xi’an University of Technology (Grant No. 2019KFKT-10).

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Streams and rivers, especially in urban areas, are substantial sinks of bioavailable nitrogen owing to their hydrological connections with terrestrial systems and the intensity of inputs mediated by human activities. Denitrification can account for nitrogen removal in rivers, but its importance in urban rivers has been scarcely studied. This study chose 8 representative rivers in Shanghai, under different level of urbanization, and measured denitrification rates of sediments across a year. The results showed significant differences in temporal, spatial and vertical distributions (p

The identification of protein-drug interaction plays an important role in the early stage of drug discovery. Recently, deep learning has been introduced into this area and gained excellent results, which mainly benefits from effective representations of protein and drug. However, the sparseness of raw input data builds the fundamental barrier for protein and drug representation learning. In this paper, we propose an end-to-end model representing better the characteristics of protein and drug to estimate binding affinity between protein and drug. By incorporating protein sequence, protein contact map and drug SMILES, our model achieves better results on PDBbind dataset as compared to 3D structure based classical deep model Pafnucy. Moreover, we explore the effects of different parts of our model with ablation study and find that by combining all the modules of our model we can get the best predictive results.

Side-stream enhanced biological phosphorus removal process (S2EBPR) refers to modified EBPR configurations that have been demonstrated to improve the performance stability and offer a suite of advantages compared to conventional EBPR design. Design and optimization of S2EBPR requires modification of the current EBPR models that were not able to fully reflect the metabolic functions of and competition between the PAOs and GAOs under extended anaerobic conditions as in the S2EBPR conditions. In this study, we proposed and validated an improved iEBPR model for simulating PAO and GAO competition that incorporated heterogeneity and versatility in PAO sequential polymer usage, staged maintenance-decay and glycolysis-TCA pathway shifts. The iEBPR model was first calibrated against a bulk batch test experimental data. The improved iEBPR model performed better than the previous EBPR model for predicting the soluble orthoP, ammonia, biomass glycogen and PHA temporal profiles in a batch starvation testing under prolong anaerobic conditions. We further validated the model with another independent set of batch anaerobic batch testing data that included high-resolution cellular and population-level intracellular polymers measurements enabled by single-cell Raman microspectroscopy technique. The model accurately predicted the temporal changes in the intracellular polymers at cellular and population levels within PAOs and GAOs, further confirmed the proposed mechanism of sequential polymer utilization, and polymer availability-dependent and staged maintenance and decay in PAOs. These results indicate that under extended anaerobic phases as in S2EBPR, the PAOs may gain competitive advantage over GAOs due to the possession of multiple intracellular polymers and the adaptive switching of the anaerobic metabolic pathways that consequently lead to the later and slower decay in PAOs than GAOs. The iEBPR model can be applied to facilitate and optimize the design and operations of S2EBPR for more reliable nutrient removal and recovery from wastewater.

Designing a swarm of robots to address different tasks and adapt to various environments through self-assembly is one of the most challenging topics in the field of robotics research. Here, we present an assembly robotic system with inchworm robots as modules. The system is called BioARS (Bionic Assembly Robotic System). It can either work as a swarm of individual untethered inchworm robots or be assembled into a quadruped robot. The inchworm robots are connected by magnets using a "shoulder-to-shoulder" connecting method, which helps strengthen the magnetic connection. Central pattern generators are used to control the trot gait of the quadruped robot. Our experiments demonstrate that the bionic assembly system is adaptive in that it can pass through confined spaces in the form of inchworms and walk on rough terrain in the form of a quadruped robot. The proposed BioARS, therefore, combines the flexibility of inchworms and the adaptability of quadruped animals, which is promising for application in planetary exploration, earthquake search and rescue operations. We also provide several examples of directions for future research regarding our system.

For the application of non-cooperative target acquisition in space, the elephant-trunk robot has the advantages of self-adaptability and large-scale acquisition. However, due to the non-cooperative characteristic of space objects, the stability of the capture process cannot be guaranteed. In this paper, the stable envelope holding of elephant-trunk robot is studied. The whole structure of the robot is a series structure, which can capture the object by envelope holding. On this basis, the holding range and stability of the elephant-trunk robot were studied, and the holding model was established. According to the holding state and holding stability of the elephant-trunk robot, the optimal holding contact point is planned to realize stable envelope holding.

Identifying vital nodes in complex networks is of paramount importance in understanding and controlling the spreading dynamics. Currently, this study is facing great challenges in dealing with big data in many real-life applications. With the deepening of the research, scholars began to realize that the analysis on traditional graph model is insufficient because many nodes in a multilayer network share connections among different layers. To address this problem both efficiently and effectively, a novel algorithm for identifying vital nodes in both monolayer and multilayer networks is proposed in this paper. Firstly, a node influence measure is employed to determine the initial leader of a local community. Subsequently, the community structures are revealed via the Maximum Influential Neighbors Expansion (MINE) strategy. Afterward, the communities are regarded as super-nodes for an iteratively folding process till convergence, in order to identify influencers hierarchically. Numerical experiments on 32 real-world datasets are conducted to verify the performance of the proposed algorithm, which shows superiority to the competitors. Furthermore, we apply the proposed algorithm in the graph of adjacencies derived from the maps of China and USA. The comparison and analysis of the identified provinces (or states) suggest that the proposed algorithm is feasible and reasonable on real-life applications.

The influence maximization problem (IMP) in complex networks is to address finding a set of key nodes that play vital roles in the information diffusion process, and when these nodes are employed as &rdquo, seed nodes&rdquo, the diffusion effect is maximized. First, this paper presents a refined network centrality measure, a refined shell (RS) index for node ranking, and then proposes an algorithm for identifying key node sets, namely the reject neighbors algorithm (RNA), which consists of two main sequential parts, i.e., node ranking and node selection. The RNA refuses to select multiple-order neighbors of the seed nodes, scatters the selected nodes from each other, and results in the maximum influence of the identified node set on the whole network. Experimental results on real-world network datasets show that the key node set identified by the RNA exhibits significant propagation capability.

This paper focuses on the research of diversified e-commerce activities in e-commerce platform, mapping various business activities into the framework of resource allocation. When a certain number of users access the platform concurrently, the system allocates resources. This paper abandons the traditional simple filtering mode to analyze the historical data of e-commerce platform, abstracts the user commodity binary network and divides the user communities according to the attribute information of users and commodities and the purchase logs of users. By analyzing the community of users, we can allocate resources reasonably. In the binary network of users and goods, there are still many problems in user based clustering. For example, the sparseness of user attribute information, the proportion of intersection between users' purchasing goods is too small and so on. According to the characteristics of data and the existing problems, this paper selects the SimRank algorithm and improves it. In this paper, a combined similarity index based on user attributes and network structure is proposed to improve the accuracy of user clustering, and a reasonable scheme of resource allocation is proposed by using the community division of users, which increases the accuracy of user clustering, achieves the expected design goals, and improves work efficiency.