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The raw materials of Poly(ethylene terephthalate) (PET) are derived from petroleum‐based resources, which are no sustainable. Therefore, previous researchers introduced biomass‐derived 2,5‐tetrahydrofurfuryl dimethanol (THFDM) into PET. However, its heat resistance has decreased compared to PET. In this paper, a novel bio‐based copolyester, poly(ethylene glycol‐co‐2,5‐tetrahydrofuran dimethanol‐co‐isosorbide terephthalate) (PEIFT), is prepared by introducing biomass‐derived isosorbide (ISB) and THFDM into the PET chains through melting copolymerization process. With the introduction of ISB content, copolyesters' hydrophilicity and rigidity improve. Compared to PET, glass transition temperature (Tg) increases by over 5 °C. In addition, the toughness and spinning performance of PEIFT have also been improved as a result of the addition of THFDM components. The hydrophobicity of PEIFTs electrospinning is greatly improved, with a contact angle exceeding 135°. Finally, due to the good hydrophobicity of PEIFTs nanofibers, they have potential application value in the manufacture of hydrophobic nanofiber and filter films. Given its biomass source and excellent performance, they make it easier to replace materials derived from petroleum. [ABSTRACT FROM AUTHOR]

The packing of hard segment in polyurethane hard domain has not been resolved or seen clearly yet. In this work, we prepared polyurethane blends, which were composed of different weight ratios of crystallizable 1195A and non‐crystallizable EG85A, to study the structural evolution and crystallization in mixed hard domain. Time and temperature dependent differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), and x‐ray diffraction results were used to record the micro‐phase evolution and crystallization processes. It was very surprising to find that the multiple melting temperatures in these blends were similar. We deduced that the packing of hard segment tended to separate into different groups, probably dependent on their segmental length. The crystalline nucleus was consist of 1195A hard segments with similar length, and the out‐layer structure was consisted of mixed hard segments of varying lengths. The FTIR results demonstrated that crystallinity did not affect the degree of hydrogen bonding association (HBA), and the stacking of hard segments may be only differed in the degree of ordering. Moreover, the degree of HBA of the blends was always higher than the calculated number based on weight ratio of pure samples. [ABSTRACT FROM AUTHOR]

Both graphene and hexagonal boron nitride (h‐BN) have found their application in catalysis and electronic devices owing to their unique π electronic nature. However, it remains unclear on how their sizes and growing modes influence their electronic properties. In order to extensively understand their structure–property relationship to stimulate and assist potential applications, in this work, the electronic structures of the polyaromatic hydrocarbons (PAHs) and polyborazines (boron nitride nanosheets, BNNSs) were analyzed by means of density functional theory calculations to investigate how the one‐ and two‐dimensional growth of their building blocks, benzene and borazine, respectively, may modulate/govern their aromaticity and reactivities. The analysis shows that the aromaticity and reactivity of PAHs exhibit significant response to their geometries, while the properties of BNNSs show strong localization nature and are nearly size‐independent. This unique nature of BNNSs is different from both the organic polyaromatic molecules and the inorganic metal/metal oxides whose reactivity may be significantly enhanced upon modulating their sizes, and offers implications in the design of new materials grafted by BNNS for manipulatable electronic properties. This study also brings caution on the application of widely used aromaticity descriptors, and shows that in general the descriptors derived from electronic structure are more reliable. [ABSTRACT FROM AUTHOR]

The photocatalytic conversion of soluble U(VI) into insoluble U(IV) is a robust strategy to harvest aqueous uranium, but remains challenging owing to the intermittent availability of solar influx and reoxidation of U(IV) without illumination. Herein, a dual platform based on K+ and cyano group co‐decorated poly(heptazine imide) (K‐CN‐PHI) is reported that can drive persistent U(VI) extraction upon/beyond light. K‐CN‐PHI achieves the photocatalytic reduction of U(VI) with a reaction rate of 0.89 min−1, being 47 times greater than that over pristine carbon nitride (PCN). This system can further be triggered by light to form long‐living radicals, driving the reduction of U(VI) in the dark for over 3 d. The flexible structural K+ as counterions stabilize the electrons trapped by cyanamide groups, enabling the long lifetime of the generated radicals. The results collectively prove K‐CN‐PHI to be a novel and efficient photocatalyst enabling persistent U(VI) extraction around the clock, and broadening the practical applications of the photocatalytic extraction of U(VI). [ABSTRACT FROM AUTHOR]

Intertidal wetlands 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 different discharge estuaries hampers the assessment of the carbon storage potential in these systems. In this study, based on the elemental ratios and stable carbon isotopes of the core sediment from the intertidal wetlands along the east coast of China, we quantified the contribution of organic carbon (OC) derived from terrestrial/estuarine particulate organic matter (POM), marine phytoplankton, and local plants, such as mangrove and salt marsh plants in the study area. We explored the hydrological and plant drivers controlling the variation in the contribution of OC sources among different coastal environmental settings. We found that SOC in high discharge estuaries (river runoff more than 50 billion m3/a) originated predominantly from terrestrial/estuarine POM (45 ± 6%), whereas the primary source for low discharge estuaries was marine phytoplankton OC (51 ± 14%). Moreover, our estimates revealed a sharp increase in the contribution of OC from mangroves to deep sediments compared with surface sediments, owing to the infiltration of mangrove roots at greater depths and the slow degradation of roots contributing to the substantial refractory OC buried in the deep sediments. These findings indicate that carbon storage in the intertidal wetlands varies among contrasting coastal environmental conditions, which provides implications for intertidal wetlands as a critical carbon sink in the global carbon budget. Plain Language Summary: Better constraints on the sources of sediment organic carbon (SOC) in intertidal wetlands are very important for calculating the global carbon budget. Many researchers have studied the distribution, source, burial of SOC, but still, there is an obvious lack of quantification of the contributions of multiple SOC sources in different discharge estuaries across a large geographical area. Terrestrial/estuarine particulate organic matter (POM), marine phytoplankton, and local plants contribute organic carbon (OC) to sediments, varying in different places. In this study, by comparing the total organic carbon and total nitrogen content, δ13C values, and C/N ratios of the sediment cores, we quantified the relative contributions of three OC sources to sediments from 12 intertidal wetlands along the east coast of China. We found a higher percentage of terrestrial/estuarine POM input in high discharge estuaries (river runoff more than 50 billion m3/a). Results suggest that the contribution of terrestrial/estuarine POM increases with river runoff, whereas the contribution of marine phytoplankton OC decreases with runoff. Moreover, there was a sharp increase in the relative contribution of long‐term OC supplied by mangrove OC with depth. The large‐scale quantification of the contributions of SOC sources has important implications for better estimation of the potential of OC sequestration. Key Points: Organic carbon (OC) contribution was assessed in coastal wetlands of China by using MixSIARThe contribution of terrestrial/estuarine particulate organic matter rose with river runoff, while the contribution of marine OC decreasedThe infiltration of mangrove roots resulted in mangrove OC dominated in deeper sediments and preserved [ABSTRACT FROM AUTHOR]

Estuaries and coasts are areas of intense biogeochemical cycling and are sensitive to global climate change. However, the effect of temperature increase on the emissions of the powerful greenhouse gas nitrous oxide (N2O) in different estuarine and coastal areas is still uncertain. In this study, we used laboratory incubation experiments to investigate increasing temperatures (12, 25, and 35°C) and tidal effects on N2O fluxes in intertidal sediments from the East China coast (ECC). Overall, the ECC acts as a net source of atmospheric N2O and exhibited considerable spatial variability over three orders of magnitude (from −0.17 to 8.4 μmol m−2 h−1). The warming promoted N2O emissions in most intertidal areas, while reducing N2O emissions at some sampling sites. In addition, the overall effect of flooding on N2O emissions changed from a positive to a negative effect with increasing temperature. By combining the sediment properties of all the sampling sites, we found that large differences in N2O emissions at the same amended floodwater nitrogen concentration were due to the quality and quantity of sediment organic matter. Sediment derived mainly from marine sources emitted more N2O than sediment derived from terrestrial sources. This suggests that the mangroves, salt marshes, and intertidal zones of estuaries have a mitigating effect on N2O emissions due to their elevated terrestrial organic matter inputs. This research improves our understanding of the impact of future global climatic changes on intertidal N2O fluxes, which can inform future studies and models and can be used to constrain intertidal N2O emissions. Plain Language Summary: Nitrous oxide (N2O) is one of the most potent greenhouse gases in the world, resulting in intensified global warming and contributing to the destruction of the ozone layer. Coasts and estuaries are often to release N2O through sediment‐air and water‐air interfaces that are regulated by tidal flooding. In this study, we used laboratory incubation experiments to investigate the responses of N2O emissions to increasing temperature in intertidal sediments from the East China coast. We found that the responses of N2O varied across sediments with different characteristics, wherein those dominated by terrestrial organic matter displayed decreased N2O emissions, and those derived mainly from marine sources showed increased N2O emissions. The quality and quantity of sediment organic matter were key to the variance in N2O fluxes. In the future, climate change will affect global N2O fluxes by altering the intrinsic characteristics (e.g., carbon or nitrogen composition in the sediment) of intertidal sediments. This study provides new insight into the mechanisms of N2O production and consumption and may be useful for policy makers tasked with controlling and mitigating the effects of global warming by allowing for improved estimates of global N2O emissions. Key Points: The N2O fluxes increased with the rising temperature in most intertidal areas, while reducing at some sampling sitesThe effect of flooding on N2O emissions changed from a positive to a negative effect with increasing temperatureThe sediment dominated by marine sources emits more N2O fluxes under the warming condition than sediment derived from terrestrial sources [ABSTRACT FROM AUTHOR]

We first review current knowledge on PAOs, with a focus on bacteria, in terms of their phylogenetic identities, metabolic pathways and detection methods. Our preliminary investigation of the presence of PAOs in lake sediment implied the role of PAOs in the seasonal release of phosphorus from the sediment (Zhou I et al i ., 2020). The biological component of most global P cycling models is based on a presumed C/N/P ratio of cells, whereas PolyP storage and degradation alters the C/N/P ratio and influences the fate and transformation of P species that can be rather significant. Sequencing the conserved regions of polyphosphate kinase ( I ppk i ) and exopolyphosphatase genes has been used to delineate higher-level phylogenetic (micro)diversity of PAOs beyond that offered by 16S rRNA sequencing, and to identify clades within each PAO lineage (McMahon I et al i ., 2007). [Extracted from the article]

Background. Many doctors ignored the possibility that there is still a spinal cord compression (SCC) need for decompression after atlantoaxial reduction. Reduction can be achieved on kinematic magnetic resonance imaging (MRI); thus, we want to analyze the role of kinematic MRI in reducible atlantoaxial dislocation and make a preoperative decision whether to perform decompression. Methods. 36 patients with atlantoaxial reduction on preoperative kinematic MRI in extension postures were enrolled retrospectively. Grouping was based on the condition of SCC after atlantoaxial reduction preoperatively. Group A: patients with SCC after atlantoaxial reduction on dynamic cervical MRI were treated with C1 laminectomy for decompression and atlantoaxial fixation. Group B: patients with no significant SCC, according to dynamic MRI, underwent only atlantoaxial fixation. Clinical outcomes were evaluated using JOA score for spinal cord function. Radiological outcomes were assessed by measuring spinal cord diameter on MRI. Results. The mean follow-up time was 17.1 months. Postoperative JOA score and percentage of SCC in both groups were significantly better than its preoperative score. There were no significant statistical differences in the JOA score at 12 months after surgery and the JOA improvement rate between two groups. All patients in the two groups had a lower percentage of SCC on preoperative extension MRI, compared with neutral MRI. No significant statistical differences in the spinal decompression improvement rate were observed between the two groups. Conclusions. Decompression should be performed in patients who still have significant SCC on preoperative kinematic MRI. Kinematic MRI could be used to assess SCC and decide whether to perform decompression preoperatively. [ABSTRACT FROM AUTHOR]

Tidal flats form around the estuarine and coastal zone by continuous terrigenous sediment transport and deposition processes. Now a large body of published carbon research work frame within the vegetated area (mangrove forests, sea grass bed, and salt marshes). Nonvegetated tidal flats, which are characterized by predominantly silts and clays sediment, were generally impressed with low carbon stock due to their meager primary productivity. However, these regions may be a potentially important carbon sink, given their high burial rate, expanding areal coverage, and detrial organic carbon derived from watershed and adjacent vegetated area. Low carbon densities (<0.01 g cm−3) were found in Chinese tidal flat sediments by the study, but the carbon sequestration rates ranged from 35 to 361 g C m−2 yr−1, which were comparable to rates of worldwide vegetated coastal areas. The high rates can be ascribed to rapid sedimentation rates (1–2 cm yr−1) during the past several decades. The highest areal carbon stocks were located at tidal flat sites proximal to mangrove forests. The majority of carbon stocks (100 cm) was found in the unvegetated tidal flats instead of in the vegetated tidal flats. The former occupied 87% of the entire tidal area, 6.7 times larger than the latter. Tidal flats in coastal China store 78.07 Tg C (100 cm), accounting for nearly 80% of the C deposited in entire coastal tidal area. The future carbon sequestration rates of Chinese tidal flats are facing uncertainties under the pressures of reduced fluvial sediment loads from major rivers. Key Points: Soil organic carbon density is lower in the Chinese unvegetated tidal flats than vegetated coastal area in the worldThe overall carbon sequestration rate of Chinese tidal flats is comparable to rates of global coastal marshesTidal flats account for nearly 80% of the C stored in the Chinese tidal area [ABSTRACT FROM AUTHOR]

While aquaculture ponds are potentially important sources of atmospheric N2O, the magnitude and variability of N2O concentrations and fluxes both within and across the ponds remain poorly understood. In this study, we examined the small‐scale spatial variations of dissolved N2O concentrations in water and N2O fluxes across the water‐air interface from three mariculture ponds in a subtropical estuary in southeast China. Our results showed that the dissolved concentrations and diffusive fluxes of N2O in the shrimp ponds ranged between 2.3–19.2 nM and 16.4–589.7 nmol m−2 hr−1, respectively, over the culture period. Significant variations of N2O concentrations and fluxes were observed within the ponds, with higher values being observed in the aeration area that could be attributed to the high rates of nitrification in the water column, as well as sediment N2O production and diffusive flux into the overlying water. Also, N2O concentrations and fluxes varied significantly among the three ponds as a result of the difference in N‐NO3− and N‐NH4+ concentrations in the water column. The large fine‐scale spatial variations of N2O concentrations and fluxes observed in our aquaculture ponds suggested that management practices such as aeration and bait feeding could largely affect the extent that aquaculture activities have on N2O emissions and climate change through their influence on the physicochemical environment (e.g., oxygen and N‐NH4+ concentrations) of the ponds. Key Points: Marked spatial difference in N2O flux both between and within pondsNitrogen substrate availability and aeration affected the spatial variations of N2O fluxSubtropical estuarine aquaculture ponds were important sources of N2O [ABSTRACT FROM AUTHOR]

Cyanex301 is considered as an important extractant in liquid–liquid extraction, while its dynamics in condensed phase remains unclear. By means of molecular dynamics simulations, the biphasic behavior of Cyanex301 in water–toluene binary solvents is addressed and compared to that of its two analogs, Cyanex272 and Cyanex302. The simulations shows that deprotonated ligands retard the de‐mixing of the binary solvents compared to their neutral counterparts, but display higher surface activity, and assemble in a more orderly manner at the interface. Increasing their concentrations results in the formation of microtubule‐like structures to maximize their contact with aqueous phase, which is not observed for their native states. The presence of counterion Na+ "salts out" ligands and enhances their distribution at the interface. This work complements experimental studies of the ligands with details of their conformations and distributions at the molecular level, and is expected to contribute to the extensive development of their applications in hydrometallurgy. [ABSTRACT FROM AUTHOR]

Core IdeasWe investigated estuarine environmental factors on CH4 flux from two vegetation communities.Warming significantly affected on CH4 emission from the Phragmites australis community.There was a significant correlation between CH4 flux and water level in both communities.Salinity significantly affects CH4 emissions from the Phragmites australis community.The interaction between temperature and water level was the most important factor controlling CH4 flux. Global warming, rising sea levels, and saltwater intrusion interact to affect carbon cycling, specifically methane (CH4) flux in estuarine coastal wetlands. In the present study, Phragmites australis and Spartina alterniflora communities in the intertidal zone of the Yangtze estuary were selected for investigating CH4 flux under different temperature (natural/warming), water level (high/low), and salinity (0, 5, 15, and 30‰) conditions. The average CH4 flux (from April to October 2016) under natural conditions was 141.0 ± 21.5 and 502.8 ± 65.3 μmol m−2 h−1 for P. australis and S. alterniflora communities, respectively. Warming had a particularly pronounced effect on CH4 emissions from the P. australis community and increased CH4 flux by 130%. There was a significant correlation between CH4 flux and water level; at high water levels, CH4 flux was 2.64‐ and 3.78‐fold higher in P. australis and S. alterniflora communities, respectively. Salinity had a significant pronounced effect on CH4 emissions from the P. australis community, and there was a clear order (5‰ > 15‰ > 0‰ > 30‰) in CH4 flux. The interaction between temperature and water level was the most important factor controlling CH4 flux from wetlands; CH4 emissions were greater at higher temperature and higher water levels. However, at low water level, the effect of salinity was more prominent. The results suggest that CH4 flux from estuarine wetlands could be further enhanced in the future under the influence of rising sea levels due to global warming. [ABSTRACT FROM AUTHOR]

Based on the features of microemulsion flooding in low-permeability reservoir, a three-dimension three-phase five-component mathematical model for microemulsion flooding is established in which the diffusion and adsorption characteristics of surfactant molecules are considered. The non-Darcy flow equation is used to describe the microemulsion flooding seepage law in which the changes of threshold pressure gradient can be taken into account, and the correlation coefficients in the non-Darcy flow equation are determined through the laboratory experiments. A new treatment for the changes of threshold pressure and the quantitative description of adsorption quantity of surfactant and relative permeability curves are presented, which enhance the coincidence between mathematical model and experiment results. The relative errors of main development indexes are within 4%. A software is programmed based on the model to execute a core-level small-scale numerical simulation in Chaoyanggou Oilfield. The fitting relative errors of the pressure, flow rate, and moisture content are 3.25%, 2.71%, and 2.54%, respectively. The results of laboratory experiments and numerical simulation showed that microemulsion system could reduce the threshold pressure gradient by 0.010 MPa/m and injection pressure by 0.6 MPa. The biggest decline in moisture content reaches 33%, and the oil recovery is enhanced by 10.8%. [ABSTRACT FROM AUTHOR]

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*)2UR [Tp*=hydrotris(3,5‐dimethylpyrazolyl)‐borate ligand, R= −C≡CPh (Cpda‐CC), −C≡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‐κ1‐O2C] intermediate, followed by the reorientation of the carboxylate group to coordinate with the U atom in the κ2 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

Abstract: A formal [5+3] cycloaddition of zwitterionic allylpalladium intermediates with 1,3‐dipoles is developed, providing N,O‐containing eight‐membered heterocyclic compounds in high yields. Catalytically generated zwitterionic allylpalladium intermediates in situ from vinylethylene carbonates or vinyloxiranes acted as dipolarophile. [ABSTRACT FROM AUTHOR]

Oxidative dehydrogenation of propane to olefins is a promising alternative route to industrialized direct dehydrogenation, but encounters the difficulty in selectivity control for olefins because of the overoxidation reactions that produce a substantial amount of undesired CO2. Here we report edge-hydroxylated boron nitride, a metal-free catalyst, that efficiently catalyzed dehydrogenation of propane to propylene with superior selectivity (80.2 %) but with only negligible CO2 formation (0.5 %) at a given propane conversion of 20.6 %. Remarkable stability was evidenced by the operation of a 300 h test with steady conversion and product selectivity. The active BNO. site, generated dynamically through hydrogen abstraction of B−OH groups by molecular oxygen, triggered propane dehydrogenation by selectively breaking the C−H bond but simultaneously shut off the pathway of propylene overoxidation towards CO2. [ABSTRACT FROM AUTHOR]

The dehydrogenation of bioethanol to acetaldehyde and hydrogen is a sustainable process, owing to the atom-economical transformation and easy separation of the products. However, oxide-supported Cu catalysts show a low selectivity to acetaldehyde because of considerable side reactions caused by their oxygen-rich surfaces. A conventional carbon-supported Cu catalyst shows high selectivity, but is quickly deactivated owing to the migration and agglomeration of copper particles. Here, we have produced a highly porous nitrogen-rich carbon support that contains 6.2 wt % N and can nicely disperse and stabilize Cu nanoparticles (∼6.3 nm). If used for ethanol dehydrogenation, approximately 98 % selectivity to acetaldehyde has been achieved, with excellent anti-agglomeration ability for as long as 500 min. X-ray photoelectron spectroscopy (XPS) data prove that electrons transfer to the Cu particles from the N sites. Theoretical calculations further show that nitrogen sites enhance the adsorption of Cu20 clusters and can stabilize them against coalescence and that graphitic-N sites (approximately 40 % of total N content) are the most significant. [ABSTRACT FROM AUTHOR]

Revealing the structural features of social networks is vitally important to both scientific research and practice, and the explosive growth of online social networks in recent years has brought us dramatic advances to understand social structures. Here we proposed a community detection approach based on user interaction behavior in weighted dynamic online social networks. We researched interaction behaviors in online social networks and built a directed and unweighted network model in terms of the Weibo following relationships between social individuals at the very beginning. In order to refine the interaction behavior, level one fuzzy comprehensive evaluation model was employed to describe how closely individuals are connected to each other. According to this intimate degree description, weights are tagged to the prior unweighted model we built. Secondly, a heuristic community detection algorithm for dynamic network was provided based on the improved version of modularity called module density. As for the heuristic rule, we chose greedy strategy and merely fed the algorithms with the changed parts within neighboring time slice. Experimental results show that the proposed algorithm can obtain high accuracy and simultaneously get comparatively lower time complexity than some typical algorithms. More importantly, our algorithm needs no a priori conditions. [ABSTRACT FROM AUTHOR]

BACKGROUND The effluent from pulp and paper mills is difficult to treat effectively via conventional biochemical processes due to the high concentration of lignin and its derivatives. In this study, the integration of electrochemical oxidation and biodegradation ( EO-BD) for Kraft lignin ( KL) was proposed to potentially enhance the efficiency of the treatment. Typical anodes, titanium based antimony doped tin dioxide electrodes (Ti/Sb- SnO2), were used in the pre-degradation of KL solution (1000 mg L−1), followed by post-biodegradation using aerobic flora as inocula. Response surface methodology ( RSM) was applied to optimize the EO-BD of KL. RESULTS The optimum conditions obtained via RSM were: current density 3.68 mA cm−2, electric quantity 14.49 kC and pH 9.0. Under these conditions, the maximum chemical oxygen demand ( COD) removal rate and minimum specific energy consumption were predicted by the correlation developed to be 70.83% and 28.84 kWh kg−1 COD, respectively, which agreed well with the experimental data. The results of gas chromatography-mass spectrometry ( GC-MS) analysis indicated that KL was partially degraded by EO, which was beneficial to the subsequent biodegradation. CONCLUSION This study validated the technical feasibility of adopting the EO-BD process to enhance KL degradation. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The individual and competitive adsorption of PbII, NiII, and SrII on graphene oxides (GOs) was investigated by experimental and density functional theory (DFT) studies. Experimental results indicate that 1) in all the single, binary, and ternary metal-ion adsorption systems, the sequence of maximum adsorption capacities is PbII>NiII>SrII on GOs; 2) the desorption hysteresis of metal ions from GOs shows the adsorption affinity in the same sequence: PbII>NiII>SrII. For the first time, DFT calculations indicate that 1) PbII and NiII prefer to interact with the COH group, whereas SrII interacts with COH and COC comparably, and 2) PbII can easily abstract the OH group from the GOs to form the much more stable Pb(OH)-GO complex. These findings are very important and useful for understanding the mechanisms of heavy-metal-ion adsorption on GOs and assessing the adsorption of coexisting heavy-metal ions on GOs. [ABSTRACT FROM AUTHOR]

A diverse superfamily of phospholipases consisting of the type VI lipase effectors Tle1-Tle5 secreted by the bacterial type VI secretion system (T6SS) have recently been identified as antibacterial effectors that hydrolyze membrane phospholipids. These effectors show no significant homology to known lipases, and their mechanism of membrane targeting and hydrolysis of phospholipids remains unknown. Here, the crystal structure of Tle1 (∼96.5 kDa) from Pseudomonas aeruginosa refined to 2.0 Å resolution is reported, representing the first structure of this superfamily. Its overall structure can be divided into two distinct parts, the phospholipase catalytic module and the putative membrane-anchoring module; this arrangement has not previously been observed in known lipase structures. The phospholipase catalytic module has a canonical α/β-hydrolase fold and mutation of any residue in the Ser-Asp-His catalytic triad abolishes its toxicity. The putative membrane-anchoring module adopts an open conformation composed of three amphipathic domains, and its partial folds are similar to those of several periplasmic or membrane proteins. A cell-toxicity assay revealed that the putative membrane-anchoring module is critical to Tle1 antibacterial activity. A molecular-dynamics (MD) simulation system in which the putative membrane-anchoring module embedded into a bilayer was stable over 50 ns. These structure-function studies provide insight into the hydrolysis and membrane-targeting process of the unique phospholipase Tle1. [ABSTRACT FROM AUTHOR]

B3LYP and MP2 methods are used to study the hydroxylation and dehydrogenation of thymine at different sites in the presence of hydroxyl radicals (⋅OH). With a 6-311++G(d,p) level of description, the consistent results thermodynamically show that the relative free energy increases in the order of CM5 < N1 < C6 < N3 on the hydrogen abstraction. However, toward the hydroxylation, though the two methods give a similar trend that free energy barrier increases in the order of C6 < C5 < C4 < C2, they describe the reaction at C6 site in a different way: B3LYP calculation gives a barrierless pathway, whereas MP2 calculation gives a reactant complex with an energy of 19.5 kJ/mol and a pathway with a barrier energy of 64.9 kJ/mol. The calculated results are consistent with experimental data and the preference for the C5 site is due to the facility of ⋅OH in approaching the substrate. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Global nitrogen (N) enrichment has resulted in increased nitrous oxide ( N2O) emission that greatly contributes to climate change and stratospheric ozone destruction, but little is known about the N2O emissions from urban river networks receiving anthropogenic N inputs. We examined N2O saturation and emission in the Shanghai city river network, covering 6300 km2, over 27 months. The overall mean saturation and emission from 87 locations was 770% and 1.91 mg N2O-N m−2 d−1, respectively. Nitrous oxide ( N2O) saturation did not exhibit a clear seasonality, but the temporal pattern was co-regulated by both water temperature and N loadings. Rivers draining through urban and suburban areas receiving more sewage N inputs had higher N2O saturation and emission than those in rural areas. Regression analysis indicated that water ammonium ( NH4+) and dissolved oxygen ( DO) level had great control on N2O production and were better predictors of N2O emission in urban watershed. About 0.29 Gg N2O-N yr−1 N2O was emitted from the Shanghai river network annually, which was about 131% of IPCC's prediction using default emission values. Given the rapid progress of global urbanization, more study efforts, particularly on nitrification and its N2O yielding, are needed to better quantify the role of urban rivers in global riverine N2O emission. [ABSTRACT FROM AUTHOR]

A molecular-dynamics (MD) simulation study of two heptapeptides containing α- and β-amino acid residues is presented. According to NMR experiments, the two peptides differ in dominant fold when solvated in MeOH: peptide 3 adopts predominantly β-hairpin-like conformations, while peptide 8 adopts a 14/ 15-helical fold. The MD simulations largely reproduce the experimental data. Application of NOE atomatom distance restraining improves the agreement with experimental data, but reduces the conformational sampling. Peptide 3 shows a variety of conformations, while still agreeing with the NOE and 3 J-coupling data, whereas the conformational ensemble of peptide 8 is dominated by one helical conformation. The results confirm the suitability of the GROMOS 54A7 force field for simulation or structure refinement of mixed α/ β-peptides in MeOH. [ABSTRACT FROM AUTHOR]

The Front Cover shows an edge‐hydroxylated boron nitride that can efficiently catalyze the oxidative dehydrogenation of propane to propylene.In their Full Paper, L. Shi et al. demonstrate that boron nitride, upon steam activation to generate B−OH groups at the edges, offers rather high selectivity toward propylene (up to 80.2 %) and a significantly minimized CO2 emission at a given propane conversion of 20.6 %. The hydrogen abstraction of B−OH groups by molecular oxygen dynamically generates the active sites, which triggered propane dehydrogenation by selectively breaking the C−H bond, but simultaneously shuts off the pathway of propylene over‐oxidation towards CO2. More information can be found in the Full Paper by L. Shi et al. on page 1788 in Issue 10, 2017 (DOI: 10.1002/cctc.201700004). [ABSTRACT FROM AUTHOR]

Review: 143 refs. [ABSTRACT FROM AUTHOR]

The article presents chemical equations for an article "Direct Access to Isoindolinone Derivatives by Palladium-Catalyzed C-H Activation and Isocyanide Insertion by Using Molecular Oxygen as the Sole Oxidant" by D. Wang and others, published in the periodical "Synthesis" in 2014.

The Rh-catalyzed coupling of N-allyl sulfonamides (I) with alkyl acrylates (II) in the presence of silver acetate as an oxidant yields (Z,E)-dienes (III) as sole reaction products. [ABSTRACT FROM AUTHOR]

Depending on the reaction conditions, the oxidative Rh-catalyzed and Ag(I)-mediated process provides pyridine or sterically defined cyclopentanone scaffolds. [ABSTRACT FROM AUTHOR]

Review: 355 refs. [ABSTRACT FROM AUTHOR]