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Reduced graphene oxide (RGO)/Fe nanocomposites were synthesized by a facile one-step reduction reaction, using reduced graphene oxide and FeSO4•7H2O as raw materials. These RGO/Fe nanocomposites combine Fe nanoparticles with graphene in various thicknesses. The results show that the residual defects and groups in chemically reduced graphene oxide brought about defect polarization relaxation and groups' electronic dipole relaxation, which both make the electromagnetic absorbing performance of RGO/Fe nanocomposites better than that of pure Fe nanoparticles. Most importantly, this paper reveals that graphene with different thicknesses has a great influence on the microwave-absorbing properties of the composites. There was serious agglomeration in RGO/Fe nanocomposites synthesized by thin graphene, while the graphene of a certain thickness could support the nanoparticles on its surface, thereby reducing the effect of agglomeration on the composite material and giving full play to dielectric loss properties of the graphene. [ABSTRACT FROM AUTHOR]

In view of the final destination of nanomaterials, the water system would be an important sink. However, the environmental behavior of nanomaterials is rather confusing due to the complexity of the real environment. In this study, a freshwater ecosystem, including water, sediment, water lettuce, water silk, Asian clams, snails, water fleas, Japanese medaka, and Yamato shrimp, was constructed to study the distribution, bioaccumulation, and potential impacts of CeO2 nanoparticles (CeO2 NPs) via long-term exposure. The results demonstrated most of the CeO2 NPs deposited in the sediment (88.7%) when the partition approached to the constant 30 days later. The bioaccumulated Ce in six tested biota species was negatively correlated with its trophic level, showing no biomagnification of CeO2 NPs through this food web. CeO2 NP exposure induced visual abnormalities in hydrophytes, including chlorophyll loss in water silk and water lettuce, ultrastructural changes in pyrenoids of water silk, and root elongation in water lettuce. The generation of hydroxyl radical (·OH) and cell-wall loosening induced by CeO2 NP exposure might mediate the root growth in water lettuce. The findings on the environmental behavior of CeO2 NPs in water system have provided useful information on the risk assessment of nanomaterials. [ABSTRACT FROM AUTHOR]

The interactions between monovalent counterions and polyelectrolyte are important in chemical and biological systems. The condensation and screening effect of counterions complicate the polyelectrolyte solutions. By means of single-molecule AFM, the single-chain mechanics of a strong polyelectrolyte, poly(sodium styrenesulfonate) (PSSNa), in KCl aqueous solutions over almost whole concentration range have been studied. The M-FJC model has been used to describe the single-chain elasticity of PSSNa in KCl solutions with a parameter of single-chain modulus (K0). Along with the increase of the concentration of KCl from zero to almost the saturation concentration, a reentrant variation of K0 of single PSSNa chain can be observed. When [K+] is between 0.01 to 3 M, the charges on the PSSNa backbone are almost completely screened, i.e., the PSSNa chain is virtually neutral in this case. Because K0 has a positive correlation with the net charge of the polymer chain, the increased K0 at very high KCl concentrations (≥3.5 M) indicates that the chain is charged again. Due to the negative charges on the backbone of PSSNa, only the positively charged counterions (K+) can be adsorbed on the chain. Thus, the PSSNa chain should be positively charged when KCl concentrations ≥3.5 M. That is, the charge inversion occurs in this case, which is induced by a monovalent salt. This finding may lay the foundation for the future applications of drug delivery and gene therapy. [ABSTRACT FROM AUTHOR]

Polyoxyethylene(20) cetyl ether (C56H114O21, POELE20) and three sulfate salts (Li2SO4, ZnSO4, and MgSO4) were used as phase-forming material of the aqueous two-phase system, and the binodal data was measured at the three temperatures (288.15, 298.15, 308.15 K). Three classic experienced formulas were used to fit the binodal data, and they had better performance in data association. The tie-line data of studied systems were measured and fitted by the empirical formulas, i.e., Othmer-Tobias and Bancroft equations. It has better performance in data association. For the investigated systems, the influence of the salt type on the binodal curves was studied by the Gibbs free energy of ions hydration and effective excluded volume, and the influence of temperature on the tie-lines and binonal curves was also discussed. First, as it is confirmed, when the salts are of the same anion, salts with higher cation valence will have stronger abilities of salting out; the salting out abilities of salts strengthen with the increasing absolute value of Gibbs free energies of cations. Second, the salting-out abilities of salts enhance with the increase in system effective excluded volume in the investigated systems. Third, the studied aqueous two-phase systems are more prone to formation at the higher temperature than those at lower temperature. Finally, for the tie-lines in the studied systems, the absolute value of slope decreases with the temperature falling. [ABSTRACT FROM AUTHOR]

Real time online calibration of mass shift and intensity fluctuation to improve the accuracy of measurements for identification and quantitation in trace mass spectrometric analysis was demonstrated using extractive electrospray ionization mass spectrometry (EESI-MS). The signals of authentic compounds (e.g., lysine (Lys), proline (Pro), and histidine (His)) spiked into the extractive solution for the EESI process were used as the references to calibrate the signal of analytes (e.g., methionine (Met)) in the untreated sample solution. The intensity of the analyte signal was recorded simultaneously with the reference signals. The analyte signals at a given time point were calibrated on the basis of these correlation factors and real time signal response of the reference. The calibrated signal of Met at 10 µg L-1 was improved with a better signal-to-noise ratio (S/N from 2.3 to 4.3), better linearity (R² from 0.9758 to 0.9980), and reduced relative standard deviation (RSD from 9.8% to 6.0%). The shift of mass-to-charge ratio of Met signal between the detected and theoretical values was decreased from 247 ± 133 to -7 ± 167 ppm for 50 min of detection using a linear ion trap mass analyzer and was reduced from -0.27 ± 0.60 to -0.12 ± 0.23 ppm for 50 min of detection using an Orbitrap mass analyzer (P = 95%). This method has been validated using a certified standard amino acids solution (GBW(E)100062) and applied for quantitative detection of amino acids in chicken feed, urine, nutritional drink, and facial mask samples, showing that the method is useful to improve the accuracy of mass spectrometric analysis. [ABSTRACT FROM AUTHOR]

The high-density lipoprotein (HDL) receptor scavenger receptor class B, type I (SR-BI), binds HDL and mediates selective cholesteryl ester uptake. SR-BI's structure and mechanism are poorly understood. We used mass spectrometry to assign the two disulfide bonds in SR-BI that connect cysteines within the conserved Cys321-Pro322-Cys323 (CPC) motif and connect Cys280 to Cys334. We used site-specific mutagenesis to evaluate the contributions of the CPC motif and the side chain of extracellular Cys384 to HDL binding and lipid uptake. The effects of CPC mutations on activity were context-dependent. Full wild-type (WT) activity required Pro322 and Cys323 only when Cys321 was present. Reduced intrinsic activities were observed for CXC and CPX, but not XXC, XPX, or XXX mutants (X ≠ WT residue). Apparently, a free thiol side chain at position 321 that cannot form an intra-CPC disulfide bond with Cys323 is deleterious, perhaps because of aberrant disulfide bond formation. Pro322 may stabilize an otherwise strained CPC disulfide bond, thus supporting WT activity, but this disulfide bond is not absolutely required for normal activity. C384X (X = S, T, L, Y, G, or A) mutants exhibited altered activities that varied with the side chain's size: larger side chains phenocopied WT SR-BI treated with its thiosemicarbazone inhibitor BLT-1 (enhanced binding, weakened uptake); smaller side chains produced almost inverse effects (increased uptake:binding ratio). C384X mutants were BLT-1-resistant, supporting the proposal that Cys384's thiol interacts with BLT-1. We discuss the implications of our findings on the functions of the extracellular loop cysteines in SR-BI and compare our results to those presented by other laboratories. [ABSTRACT FROM AUTHOR]

The first examples of catalytic enantioselective ring-opening/cross-metathesis (EROCM) reactions that involve enol ethers are reported. Specifically, we demonstrate that catalytic EROCM of several oxa- and azabicycles, cyclobutenes and a cyclopropene with an alkyl- or aryl-substituted enol ether proceed readily in the presence of a stereogenic-at-Mo monopyrrolide-monoaryloxide. In some instances, as little as 0.15 mol % of the catalytically active alkylidene is sufficient to promote complete conversion within 10 min. The desired products are formed in up to 90% yield and >99:1 enantiomeric ratio (er) with the disubstituted enol ether generated in >90% Z selectivity. The enol ether of the enantiomerically enriched products can be easily differentiated from the terminal alkene through a number of functionalization procedures that lead to the formation of useful intermediates for chemical synthesis (e.g., efficient acid hydrolysis to afford the enantiomerically enriched carboxaldehyde). In certain cases, enantioselectivity is strongly dependent on enol ether concentration: larger equivalents of the cross partner leads to the formation of products of high enantiomeric purity (versus near racemic products with one equivalent). The length of reaction time can be critical to product enantiomeric purity; high enantioselectivity in reactions that proceed to >98% conversion in as brief a reaction time as 30 s can be nearly entirely eroded within 30 min. Mechanistic rationale that accounts for the above characteristics of the catalytic process is provided. [ABSTRACT FROM AUTHOR]

Since their first synthesis in the 1940s, zeolites have found wide applications in catalysis, ion-exchange, and adsorption. Although the uniform, molecular-size pores of zeolites and their excellent thermal and chemical stability suggest that zeolites could be an ideal membrane material, continuous polycrystalline zeolite layers for separations were first prepared in the 1990s. Initial attempts to grow continuous zeolite layers on porous supports by in situ hydrothermal synthesis have resulted in membranes with the potential to separate molecules based on differences in molecular size and adsorption strength. Since then, further synthesis efforts have led to the preparation of many types of zeolite membranes and better quality membranes. However, the microstructure features of these membranes, such as defect size, number, and distribution as well as structure flexibility were poorly understood, and the fundamental mechanisms of permeation (adsorption and diffusion), especially for mixtures, were not clear. These gaps in understanding have hindered the design and control of separation processes using zeolite membranes. [ABSTRACT FROM AUTHOR]

Gated ion diffusion is found widely in hydrophobic biological nanopores, upon changes in ligand binding, temperature, transmembrane voltage, and mechanical stress. Because water is the main media for ion diffusion in these hydrophobic biological pores, ion diffusion behavior through these nanochannels is expected to be influenced significantly when water wettability in hydrophobic biological nanopores is sensitive and changes upon small external changes. Here, we report for the first time that ion diffusion through highly hydrophobic nanopores (3 nm) showed a gated behavior due to change of water wettability on hydrophobic surface upon small temperature change or ultrasound. Dense carbon nanotube (CNT) membranes with both 3-nm CNTs and 3-nm interstitial pores were prepared by a solvent evaporation process and used as a model system to investigate ion diffusion behavior. Ion diffusion through these membranes exhibited a gated behavior. The ion flux was turned on and off, apparently because the water wettability of CNTs changed. At 298 K, ion diffusion through dense CNT membranes stopped after a few hours, but it dramatically increased when the temperature was increased 20 K or the membrane was subjected to ultrasound. Likewise, water adsorption on dense CNT membranes increased dramatically at a water activity of 0.53 when the temperature increased from 293 to 306 K, indicating capillary condensation. Water adsorption isotherms of dense CNT membranes suggest that the adsorbed water forms a discontinuous phase at 293 K, but it probably forms a continuous layer, probably in the interstitial CNT regions, at higher temperatures. When the ion diffusion channel was opened by a temperature increase or ultrasound, ions diffused through the CNT membranes at a rate similar to bulk diffusion in water. This finding may have implications for using CNT membrane for desalination and water treatment. [ABSTRACT FROM AUTHOR]

The Suzuki−Miyaura coupling of aryl nitriles with aryl/alkenyl boronic esters is reported. With this method, the cyano group could be applied as a protecting group of arenes and finally as a leaving group to further construct polyaryl scaffolds. [ABSTRACT FROM AUTHOR]

A method is presented to prepare high-density, vertically aligned carbon nanotube (VA-CNT) membranes. The CNT arrays were prepared by chemical vapor deposition (CVD), and the arrays were collapsed into dense membranes by capillary-forces due to solvent evaporation. The average space between the CNTs after shrinkage was ∼3 nm, which is comparable to the pore size of the CNTs. Thus, the interstitial pores between CNTs were not sealed, and gas permeated through both CNTs and interstitial pores. Nanofiltration of gold nanoparticles and N2adsorption indicated the pore diameters were approximately 3 nm. Gas permeances, based on total membrane area, were 1−4 orders of magnitude higher than VA-CNT membranes in the literature, and gas permeabilities were 4−7 orders of magnitude higher than literature values. Gas permeances were approximately 450 times those predicted for Knudsen diffusion, and ideal selectivities were similar to or higher than Knudsen selectivities. These membranes separated a larger molecule (triisopropyl orthoformate (TIPO)) from a smaller molecule (n-hexane) during pervaporation, possibly due to the preferential adsorption, which indicates separation potential for liquid mixtures. [ABSTRACT FROM AUTHOR]

Methods that use n-hexane ( n-hexane permporosimetry and n-hexane/2,2-dimethylybutane (DMB) separation) are shown to notbe effective for characterizing MFI zeolite membranes because n-hexane adsorption swells MFI crystals and shrinks the size of nonzeolitic pores. Measurements on a membrane in which 30% of its helium flux at 300 K was through nonzeolitic pores demonstrate that benzene permporosimetry and isooctane vapor permeation as a function of feed activity provide better characterizations. Isooctane condensed in nonzeolitic pores at high activities, and this was used to estimate the sizes of those pores. The average nonzeolitic pore size in this membrane decreased from approximately 3.0 to 1.5 nm as the temperature increased from 300 to 348 K, apparently due to thermal expansion of MFI crystals. Benzene permporosimetry yielded dramatically different results from n-hexane permporosimetry because benzene does not swell the MFI crystals significantly. Single-component pervaporation fluxes as a function of molecular kinetic diameter verified the results from benzene permporosimetry. Larger molecules had higher fluxes than n-hexane because they diffused through nonzeolitic pores that were shrunk by n-hexane adsorption. Nonzeolitic pores were estimated to account for only 0.5% of the membrane permeation area, but 30% of the helium flux, because these pores were significantly larger than MFI pores. [ABSTRACT FROM AUTHOR]

The structure of the Ag(111)(√7×√7)R19°-CH3S surface phase, formed by interaction of Ag(111) with gas-phase dimethyl disulfide, (CH3S)2, has been investigated by normal-incidence X-ray standing wave (NIXSW) analysis, using (111), (1̄11), and (200) Bragg reflections. The resulting NIXSW structural parameter values clearly exclude any simple overlayer adsorption model on an Ag unreconstructed surface. A reconstructed surface model is proposed that is consistent with the NIXSW measurements and with previous scanning tunneling microscopy results. This comprises a near-hexagonal Ag surface layer with an Ag density of only 3/7 that of the underlying substrate layers; the methanethiolate molecules are adsorbed into 3-fold coordinated hollow sites on this open layer. The results are discussed in the context of the very limited published studies of longer alkyl chain thiolates on Ag(111). [ABSTRACT FROM AUTHOR]

Defect-free, microporous Al2O3/SAPO-34 zeolite composite membranes were prepared by coating hydrothermally grown zeolite membranes with microporous alumina using molecular layer deposition. These inorganic composite membranes are highly efficient for H2 separation: their highest H2/N2 mixture selectivity was 1040, in contrast with selectivities of 8 for SAPO-34 membranes. The composite membranes were selective for H2 for temperatures up to at least 473 K and feed pressures up to at least 1.5 MPa; at 473 K and 1.5 MPa, the H2/N2 separation selectivity was 750. The H2/CO2 separation selectivity was lower than the H2/N2 selectivity and decreased slightly with increasing pressure; the selectivity was 20 at 473 K and 1.5 MPa. The high H2 selectivity resulted either because most of the pores in the Al2O3 layer were slightly smaller than 0.36 nm (the kinetic diameter of N2) or because the Al2O3 layer slightly narrowed the SAPO-34 pore entrance. These composite membranes may represent a new class of inorganic membranes for gas separation. [ABSTRACT FROM AUTHOR]

Airborne particulate pollution is a critical environmental problem affecting human health and sustainable development. Understanding of the sources of aerosol particles is of extreme importance for regional air pollution control. Here we show that natural Si isotopic signature can be used as a new tool to elucidate the sources of fine particulate matter (PM2.5). Through the analysis of Si isotopic composition (δ30Si) of PM2.5 and its primary sources collected in a typical pollution region – Beijing, we recognized the direct source tracing ability of Si isotopes for PM2.5. The different primary sources of PM2.5 had different Si isotopic signatures. The δ30Si value of PM2.5 ranged from −1.99‰ to −0.01‰ and showed a distinct seasonal trend (isotopically lighter in spring/winter and heavier in summer/autumn). The variations in δ30Si of PM2.5 revealed that Si-isotopically light sources were important sources for Beijing's severe haze pollution and that coal burning was a major cause for the aggregating haze weather in spring/winter in Beijing. We also analyzed several typical haze events by using Si isotopic signatures. As the first study on the natural Si isotopes in the atmospheric environment, this study may reveal an important tool to advance the particulate pollution research and control. [ABSTRACT FROM AUTHOR]

Tetrabromobisphenol-A/S (TBBPA/S) analogs have raised substantial concern because of their adverse effects and potential bioaccumulative properties, such as TBBPA bis(allyl ether) (TBBPA-BAE) and TBBPA bis(2,3-dibromopropyl ether) (TBBPA-BDBPE). In this study, a comprehensive method for simultaneous determination of TBBPA/S and nine novel analogs, including TBBPA-BAE, TBBPA-BDBPE, TBBPS-BDBPE, TBBPA mono(allyl ether) (TBBPA-MAE), TBBPA mono(2-bromoallyl ether) (TBBPA-MBAE), TBBPA mono(2,3-dibromopropyl ether) (TBBPA-MDBPE), TBBPS-MAE, TBBPS-MBAE, and TBBPS-MDBPE in biological samples was developed. The distribution patterns and trophic transfer properties of TBBPA/S and analogs in various biological samples collected from the Chinese Bohai Sea were then studied in detail. For the first time, TBBPA-MBAE and TBBPS-BDBPE were detected in biological samples and TBBPA-MBAE was identified as a byproduct. The concentrations of TBBPA and analogs ranged from ND (not detected or below the method detection limit) to 2782.8 ng/g lipid weight (lw), and for TBBPS and analogs ranged from ND to 927.8 ng/g lw. High detection frequencies (>86%) for TBBPA, TBBPS and TBBPA-MAE, TBBPA-MDBPE, TBBPS-MAE, TBBPS-MBAE, and TBBPS-MDBPE were obtained. Meanwhile, TBBPA, TBBPS, and these five analogs displayed trophic dilution tendencies due to significantly negative correlations between trophic levels and lipid-corrected concentrations together with the trophic magnification factors (from 0.31 to 0.55). The results also indicated the novel TBBPA-MAE, TBBPA-MBAE, TBBPA-MDBPE, TBBPS-MAE, TBBPS-MBAE, and TBBPS-MDBPE could be generated not only as byproducts, but also as the probable transformation products of commercial TBBPA/S derivatives. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) are widely distributed persistent organic pollutants. In vitro and in vivo research using various animal models have shown that PBDEs might be transformed to hydroxylated PBDEs, but there are few studies on in vivo metabolism of PBDEs by intact whole plants. In this research, pumpkin plants (Cucurbita maxima × C. moschata) were hydroponically exposed to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). A debromination product (BDE-28) and four hydroxylated metabolites (5-OH-BDE-47, 6-OH-BDE-47, 4'-OH-BDE-49, and 4-OH-BDE-42) were detected in different parts of the whole plant. In addition, 4-methoxylated-2,2',3,4'-tetraBDE (4-MeO-BDE-42) was observed as a methoxylation product. Root exudates in solution were found to play an important role in metabolizing BDE-47 to a specific OH-PBDE: 4'-OH-BDE-49. BDE-28 was found to translocate more easily and accumulate in shoots than BDE-47 due to the lower hydrophobicity and molecular weight. The concentration ratio between metabolites and parent compound BDE-47 was lower for OH-PBDEs than that for both BDE-28 and 4-MeO-BDE-42. The metabolism pathway of BDE-47 in young whole plants was proposed in this study. [ABSTRACT FROM AUTHOR]

In this study, through the choice of the well-known G-K biological coordination system, bioligand-alkali metal coordination has for the first time been brought onto an inert Au(1 11) surface. Using the interplay between high-resolution scanning tunneling microscopy and density functional theory calculations, we show that the mobile G molecules on Au(1 11) can effectively coordinate with the K atoms, resulting in a metallosupramolecular porous network that is stabilized by a delicate balance between hydrogen bonding and metal-organic coordination. [ABSTRACT FROM AUTHOR]

Single-layer graphene oxide (SLGO) is emerging as a new-generation membrane material for high-flux, high-selectivity water purification, owing to its favorable two-dimensional morphology that allows facile fabrication of ultrathin membranes with subnanometer interlayer channels. However, reliable and precise molecular sieving performance still necessarily depends on thick graphene oxide (GO) deposition that usually leads to low water flux. This trade-off between selectivity and flux significantly impedes the development of ultrathin GO membranes. In this work, we demonstrate that the selectivity/flux trade-off can be broken by self-assembly of SLGO via simple deposition rate control. We find GO membranes, prepared by slow deposition of SLGO flakes, exhibit considerably improved salt rejection, while counterintuitively having 2.5-4 times higher water flux than that of membranes prepared by fast deposition. This finding has extensive implications of designing/tuning interlayer nanostructure of ultrathin GO membranes by simply controlling SLGO deposition rate and thus may greatly facilitate their development for high flux, high selectivity water purification. [ABSTRACT FROM AUTHOR]

F-53B, the commercial product of chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs), has been used in Chinese chrome plating industry for 30 years, and was recently identified in the environment, which caused great concerns. So far, limited investigations have been performed on their environmental occurrence, fate and impact. In this study, we demonstrated the wide occurrence of Cl-PFESAs and their trophic transfer behavior in marine organisms from Chinese Bohai Sea. 6:2 Cl-PFESA (<0.016--0.575 ng/g wet weight) was the dominant congener, and 8:2 Cl-PFESA (<0.022--0.040 ng/g) was occasionally detected. Compared to other perfluoroalkyl and polyfluoroalkyl substances (PFASs) of concern, the levels of Cl-PFESAs were relatively lower in marine organisms. Based on the comparative analysis of Cl-PFESA contamination in mollusk samples collected in 2010--2014, both the concentrations and detection frequencies of Cl-PFESAs tended to increase in this region. And this kind of chemicals were more vulnerable to be accumulated in marine organisms at relatively higher trophic levels. Similar to perfluorooctanesulfonate (PFOS) and the long chain perfluorinated carboxylates (PFCAs), 6:2 Cl-PFESA could be magnified along the food chain. Accordingly, the potential threat might be posed to the wildlife and human beings due to unintended exposure to Cl-PFESAs. [ABSTRACT FROM AUTHOR]

A novel concept of utilizing nanoporous coatings as effective nanovalves on microporous adsorbents was developed for high capacity natural gas storage at low storage pressure. The work reported here for the first time presents the concept of nanovalved adsorbents capable of sealing high pressure CH4 inside the adsorbents and storing it at low pressure. Traditional natural gas storage tanks are thick and heavy, which makes them expensive to manufacture and highly energy-consuming to carry around. Our design uses unique adsorbent pellets with nanoscale pores surrounded by a coating that functions as a valve to help manage the pressure of the gas and facilitate more efficient storage and transportation. We expect this new concept will result in a lighter, more affordable product with increased storage capacity. The nanovalved adsorbent concept demonstrated here can be potentially extended for the storage of other important gas molecules targeted for diverse relevant functional applications. [ABSTRACT FROM AUTHOR]

DNA methylation (5-methylcytosine, 5mC) plays critical biological functions in mammals and plants as a vital epigenetic marker. The Ten-Eleven translocation dioxygenases (TET1, 2, and 3) have been found to oxidize 5mC to 5-hydroxymethylcytosine (5hmC) and then to 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) in mammalian cells. We report herein three mushroom TET homologues from Coprinopsis cinerea that can mediate 5mC oxidation. Specifically, one homologue (CC1G_05589, CcTET) shows similar activity to its mammalian TET homologues. Biochemically, CcTET actively converts 5mC to 5hmC, 5fC, and 5caC under natural conditions (pH 7.0). Interestingly, CcTET also converts the majority of 5mC to 5fC under slightly acidic (pH 5.8) and neutral conditions. Kinetics analyses of the oxidation by CcTET under neutral conditions indicate that conversion of 5mC to 5hmC and 5hmC to 5fC are faster than that of 5fC to 5caC, respectively. Our results provide an example of a TET homologue in a non-mammalian organism that exhibits full 5mC-to-5caC oxidation activity and a slight preference to producing 5fC. The preferential accumulation of 5fC in the in vitro oxidation reactions under both neutral and acidic conditions may have biological implications for 5mC oxidation in fungi species. [ABSTRACT FROM AUTHOR]

Although hexachlorobutadiene (HCBD) was recently proposed as a candidate persistent organic pollutant (POP) under the Stockholm Convention, information about its environmental levels and distributions is still very limited. In this work, HCBD was determined in the sewage sludge from 37 wastewater treatment plants (WWTPs) in 23 cities and 17 soils near a chemical plant in China. Three chlorobenzenes (CBs) (1,2,4-trichlorobenzene, 1,2,4,S-tetrachlorobenzene, and hexachlorobenzene) were simultaneously studied to help better understand the environmental behavior of HCBD. Concentrations of HCBD in sludge samples ranged from <0.03 to 74.3 ng/g dry weight (dw) with a median value of 0.30 ng/g dw, which was lower than those of the three CBs. Levels of HCBD were not correlated with capacity of the WWTPs and total organic carbon. For soils, high level of HCBD was found in the sample within the plant, with a rapid decreasing concentration trend with the increase of distance from the plant. It was suspected that releasing as a byproduct during manufacturing of chlorinated chemicals was the primary source of HCBD in the studied location. Further risk assessment indicated that the environmental risk of HCBD to soil organisms and the health risk to employees were very low through soil exposure within the plant. [ABSTRACT FROM AUTHOR]

Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated 8ame retardants (BFRs) and has been frequently detected in the environment and biota. Recent studies have found that derivatives of TBBPA, such as TBBPA bis(allyl) ether (TBBPA BAE) and TBBPA bis(2,3-dibromopropyl) ether (TBBPA BDBPE) are present in various environmental compartments. In this work, using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS), TBBPA allyi ether (TBBPA AE) and TBBPA 2,3-dibromopropyl ether (TBBPA DBPE) were identified in environmental samples and further confirmed by synthesized standards. Soil, sediment, rice hull, and earthworm samples collected near a BFR manufacturing plant were found to contain these two compounds. In sediments, the concentrations of TBBPA AE and TBBPA DBPE ranged from 1.0 to 346.6 ng/g of dry weight (dw) and from 0.7 to 292.7 ng/g of dw, respectively. TBBPA AE and TBBPA DBPE in earthworm and rice hull samples were similar to soil samples, which ranged from below the method limit of detection (LOD, <0.002 ng/g of dw) to 0.064 ng/g of dw and from below the LOD (<0.008 ng/g of dw) to 0.58 ng/g of dw, respectively. Furthermore, mollusks collected from the Chinese Bohai Sea were used as a bioindicator to investigate die occurrence and distribution of diese compounds in the coastal environment. The detection frequencies of TBBPA AE and TBBPA DBPE were 41 and 3296, respectively, and the concentrations ranged from below LOD (<0.003 ng/g of dw) to 0-54 ng/g of dw, with an average of 0.09 ng/g of dw, for TBBPA AE, and from below LOD (<0.008 ng/g of dw) to 1.41 ng/g of dw, with an average of 0.15 ng/g of dw, for TBBPA DBPE [ABSTRACT FROM AUTHOR]

Reactions of [Zn(Tab)4](PF6)2 (Tab = 4-(trimethyl-ammonio)benzenethiolate) (1) with 2,2'-bipyridine (2,2'-bipy), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (2,9-dmphen), N-methylimidazole (N-Meim), and 2,6-bis(pyrazol-3-yl)pyridine (bppy) or with CoCl2-6H2O at the presence of N-donor ligands (2,2'-bipy, phen, 4,4'-dimethyl-2,2'-bipyridine (4,4'-dmbpy), 2,6-bis (3,5-dimethyl-1 H-pyrazol- l-yl)pyridine (bdmppy)) gave rise to a family of zinc or cobalt thiolate com-plexes, [Zn(Tab)2(L)](PF2)2 (2: L = 2,2'-bipy, 3: L = phen, 4: L = 2,9-dmphen), [Zn(Tab)2(N-Meim)2](PF6)2 (5), [Zn(Tab)2(bppy)]-(PF6)2 (6), [Co(Tab)2(L)2](PF6)3 (7: L = 2,2'-bipy, 8: L = phen, 9: L = 4,4'-dmbpy), and [Co(Tab)(bdmppy)a](PF6) (10). These compounds were characterized by elemental analysis, IR spectra, UV--vis spectra, 'H NMR, electrospray ionization (ESI) mass spectra, and single-crystal X-ray diffraction. The Zn(n) in [Zn(Tab)2Lfa]2+dications of 2-5 is tetrahedrally coordinated by two Tab ligands and one L or two N-Meim ligands. In 6, the Zn(II) has a distorted trigonal-bipyramidal geometry, coordinated by two Tab ligands and one tridentate bppy ligand. The Co(III) in the [Co(Tab)2(L)2]3+ trications of 7-9 is octahedraly chelated by two bidentate L ligands and two Tab ligands. In 10, the Co(II) adopts a distorted trigonal-bipyramidal geometry, coordinated by one CP, one Tab ligand, and one tridentate bdmppy. In the formation of 2-6, two Tab ligands are removed from the [Zn(Tab)4]2+ dication when it is attacked by L ligands, while in the cases of 7-9, the Zn(II) of the [Zn(Tab)4]2+ dication was replaced by Co(Hi) (derived from oxidation of Co(II) by O2) followed by the removal of two Tab ligands via L ligands. In the case of 10, the central Zn(II) of the [Zn(Tab)4]2+ dication was displaced by Co(II) followed by the removal of three Tab ligands via one Cl-1 and one tridentate bdmppy. These ligand and metal replacement reactions may provide some interesting information on the interactions of the [Zn(S-Cys)4]2-unit of Zn-MTs with N-heterocydic ligands and toxic metal ions encountered in a natural environment [ABSTRACT FROM AUTHOR]