Atmospheric mercury inputs in montane soils increase with elevation: evidence from mercury isotope signatures

The influence of topography on the biogeochemical cycle of mercury (Hg) has received relatively little attention. Here, we report the measurement of Hg species and their corresponding isotope composition in soil sampled along an elevational gradient transect on Mt. Leigong in subtropical southwestern China. The data are used to explain orography-related effects on the fate and behaviour of Hg species in montane environments. The total- and methyl-Hg concentrations in topsoil samples show a positive correlation with elevation. However, a negative elevation dependence was observed in the mass- ependent fractionation (MDF) and mass-independent fractionation (MIF) signatures of Hg isotopes. Both a MIF (D199Hg) binary mixing approach and the traditional inert element method indicate that the content of Hg derived from the atmosphere distinctly increases with altitude.publishedVersio

Poly[aqua(μ3-5-aza­niumylisophthalato)­(μ-oxalato)neodymium(III)]

The title compound, [Nd(C8H6NO4)(C2O4)(H2O)]n, is a layer-like coordination polymer. The NdIII ion is coordinated by four carboxyl­ate O atoms from three bridging 5-aza­nium­yl­isophthalate (Haip) ligands, four carboxyl­ate O atoms from two oxalate (ox) anions and one ligated water mol­ecule in a tricapped trigonal–prismatic geometry. The Haip anion acts as a μ3-bridge, connecting three NdIII ions through two carboxyl­ate groups; the ox anion adopts a bis-bidentate-bridging mode, linking two NdIII ions. The layer framework is further extended to a three-dimensional supra­molecular structure through N—H⋯O and O—H⋯O hydrogen bonds

Dimension Increase via Hierarchical Hydrogen Bonding from Simple Pincer-like Mononuclear complexes

A tetradentate symmetric ligand bearing both coordination and hydrogen bonding sites, N1,N3-bis(1-(1H-benzimidazol-2-yl)-ethylidene)propane-1,3-diamine (H2bbepd) was utilized to synthesize a series of transition metal complexes, namely [Co(H2bbepd)(H2O)2]·2ClO4 (1), [Cu(H2bbepd)(OTs-)]·OTs- (2),[Cu(bbepd)(CH3OH)] (3), [Cd(H2bbepd)(NO3)2]·CH3OH (4), [Cd(H2bbepd)(CH3OH)Cl]·Cl (5), and [Cd(bbepd)(CH3OH)2] (6). These complexes show similar discrete pincer-like coordination units, possessing different arrangements of hydrogen bonding donor and acceptor sites. With or without the aid of uncoordinated anions and solvent molecules, such mononuclear units have been effectively involved in the construction of hierarchical hydrogen bonding assemblies (successively via level I and level II), leading to discrete binuclear ring (complex 2), one-dimensional chain or ribbon (complexes 3, 4 and 6) and two-dimensional layer (complexes 1 and 5) aggregates

Molecular subtypes predict the preferential site of distant metastasis in advanced breast cancer: a nationwide retrospective study

ObjectiveThis study aimed to explore possible associations between molecular subtypes and site of distant metastasis in advanced breast cancer (ABC).Methods3577 ABC patients were selected from 21 hospitals of seven geographic regions in China from 2012-2014. A questionnaire was designed to collect medical information regarding demographic characteristics, risk factors, molecular subtype, recurrence/metastasis information, and disease-free survival (DFS). The cancers were classified into Luminal A, Luminal B, HER2-enriched and Triple Negative subtypes. Chi-square test and multivariate Cox proportional hazard models were performed to explore the associations between molecular subtypes and distant metastasis sites.ResultsA total of 2393 cases with molecular subtypes information were finally examined. Patients with Luminal A (51.1%) and Luminal B (44.7%) were most prone to bone metastasis, whereas liver metastasis was more frequently observed in HER2-enriched ABC patients (29.1%).The cumulative recurrence and metastasis rates of ABC patients at 36 months of DFS were the most significant within molecular types, of which Triple Negative was the highest (82.7%), while that of Luminal A was the lowest (58.4%). In the adjusted Cox regression analysis, Luminal B, HER2-enriched and Triple Negative subtypes increased the risk of visceral metastasis by 23%, 46% and 87% respectively. In addition, Triple Negative patients had a higher probability of brain metastasis (HR 3.07, 95% CI: 1.04-9.07).ConclusionMolecular subtypes can predict the preferential sites of distant metastasis, emphasizing that these associations were of great help in choices for surveillance, developing appropriate screening and cancer management strategies for follow-up and personalized therapy in ABC patients

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Structures and luminescent properties of four compounds based on binuclear metal-terpyridine building blocks

<p>Four new coordination polymers, [Cd(3-TPTP)Cl]₂ (3-HTPTP = 4′-(3-tetrazolylphenyl)2,2′:6′2′′-terpyridine, <b>1</b>), <b>{</b>[Cd(3-TPTP)(<i>p</i>BDC)_0.5]∙4H₂O}_n (<i>p</i>H₂BDC = 1,4-benzenedicarboxylic acid, <b>2</b>), {[Mn(3-TPTP)(<i>m</i>BDC)_0.5]∙5H₂O}_n (<i>m</i>H₂BDC = 1,3-benzenedicarboxylic acid, <b>3</b>), and [Pb(3-TPTP)(H₂O)₂]∙OH (<b>4</b>), were obtained. Compounds <b>1</b>–<b>3</b> are composed of binuclear [M₂(3-TPTP)₂] ring as building unit. In <b>1</b>, the binuclear rings pack into a 3-D supramolecular framework via various hydrogen bonds. In <b>2</b> and <b>3</b>, the binuclear rings are connected by <i>m</i>BDC²⁻ and <i>p</i>BDC²⁻, respectively, resulting in two types of 1-D chains. In <b>4</b>, the mononuclear [Pb(3-TPTP)] units are connected by Pb⋯N weak interactions, giving a chiral 1-D coordination chain, which is further connected by O–H⋯N interaction to form a chiral 3-D supramolecular framework. The phase purity of <b>1</b>–<b>4</b> and luminescence properties of <b>1</b>, <b>2</b>, and <b>4</b> were also investigated.</p

Mantle-derived and crustal He and Ar in the ore-forming fluids of the Xihuashan granite-associated tungsten ore deposit, South China

The Xihuashan tungsten ore deposit in the central Nanling region, South China is a vein-type hydrothermal deposit associated with the Late Jurassic granitoids that were previously thought to be the products of crustal anatexis alone. In this study, we use helium (He) and argon (Ar) isotopes of fluid inclusions entrapped in pyrite and arsenopyrite to determine the origin of the ore-forming fluids. The He-3/He-4 ratios of the crushed fluid inclusions vary from 0.15 to 1.16 Ra, with a mean of 0.72 Ra (Ra, the atmospheric He-3/He-4 ratio of 1.4 x 10(-6)), indicating the presence of mantle-derived noble gasses in the fluids. The amounts of the mantle-derived noble gasses are estimated to be between similar to 2 and 17%. The Ar-40/Ar-36 ratios of the fluid inclusions vary from 306 to 1023, with an average of 440. These ratios are significantly higher than the average crustal value, indicating the presence of air-saturated water in the volatiles released from the mineral separates. The results from this study indicate that the associated, coeval granitoids, which is believed to provide the ore-forming fluids during magma evolution, are not the products of pure crustal melts. Mantle-derived volatiles and heat was also involved in the genesis of the host granite pluton