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Dissolved organic matter (DOM) is one of the most important ligands governing the geochemical cycling of metals in the environment, but recent studies with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) have shown enormous complexity and diversity of DOM composition. How the diverse molecular composition of DOM affects the reactivity of DOM with metals is still largely unknown, which precludes us from developing accurate geochemical models for the fate of metals in the environment. In this study, we combined FT-ICR-MS analysis and theoretical modeling approaches and specifically elucidated the link between molecular composition and the proton and Cu binding ability of DOM, using the Suwannee River fulvic acid (FA) as a model humic substance. Batch adsorption experiments were conducted to generate different extents of molecular fractionation of FA samples by ferrihydrite. FT-ICR-MS analyses were employed to investigate the changes of molecular composition while Cu titration and the Windermere Humic Aqueous Model (WHAM) were used to quantify the variations on the Cu binding capacities of FA samples. We developed a general theoretical modeling approach, which integrated a suite of theoretical modeling methods, including the Vienna Soil-Organic-Matter-Modeler (VSOMM), SPARC Performs Automated Reasoning in Chemistry (SPARC), and the linear free energy relationships (LFER), for molecular modeling based on FT-ICR-MS data. Based on the FT-ICR-MS results, we found that, despite of the complex molecular composition of FA, FA molecules can be divided into three representative groups and each group of molecules had distinct chemical properties. Interestingly, molecules within the same group had similar distributions of molecular properties. Based on the chemical properties of the three groups of FA molecules, we successfully constructed three molecular models of FA using VSOMM, and quantified the distributions of proton and Cu binding constants with SPARC and LFER. Those independently determined binding constants were comparable to the WHAM default proton and Cu binding constants, supporting the validity of our modeling approach. Our modeling results suggested that the molecular complexity of DOM may be simplified with representative groups of molecules based on their binding ability with metals in theoretical modeling. Our modeling approach based on FT-ICR-MS data shed light on developing mechanistical models for metal reactions with DOM based on the molecular data, which is helpful for predicting the geochemical cycling of carbon and metals in the environment.

The dynamic interactions among iron (Fe) oxides, organic matter (OM) and heavy metals/metalloids play crucial roles in controlling the geochemical cycling of carbon (C) and heavy metals/metalloids in natural environments. Although the inhibitory effects of arsenate (As(V)) or OM on the ferrihydrite transformation process have been studied previously, there is still a lack of mechanistic and quantitative understanding on the kinetics of As(V) and C sequestration during the Fe(II)-induced ferrihydrite transformation. In this study, we employed a suite of techniques to elucidate the underlying mechanisms accounting for the temporal changes of As(V) and C distributions and speciation on Fe oxides during the Fe(II)-induced ferrihydrite transformation process. Characterizations with X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and the spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) at different times indicated that the presence of As and/or FA resulted in the formation of more lepidocrocite than goethite. Besides surface adsorption, a portion of As(V) may be incorporated into the lattice structures of newly formed crystalline Fe oxides, and the amount of As(V) sequestration within Fe oxides were correlated with the formation of crystalline Fe oxides. In comparison, FA molecules were either adsorbed on the surfaces of goethite or diffused into the defects or nano pore spaces of lepidocrocite. Our results shed the light on different nanoscale mechanisms accounting for the sequestration of C and As(V) on Fe oxides. The defects or nano pore spaces formed in the structures of lepidocrocite may provide an effective way to sequester C through physical isolation, while the crystal structures of Fe oxides may sequester As(V) through isomorphic substitution. The knowledge on the dynamic coupling between Fe oxide transformation and C/As(V) sequestration provided the basis for accurately predicting the geochemical cycling of trace elements and OM.

Ferrihydrite is ubiquitous in natural environments, and its transformation significantly influences the fate of heavy metals. Although Pb(II) adsorption on iron oxides has been extensively studied, there is still a knowledge gap on the fate of Pb during the dynamic processes of iron oxide transformation. In this study, a set of wet chemistry experiments, spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) integrated with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS) were used to unravel Pb interactions with iron oxides during ferrihydrite transformation processes under abiotic conditions. Wet chemistry experiments, STEM-EDS elemental mapping and line scans, and quantitative analysis suggested that Pb penetrated into hematite nanoparticles during the transformation processes. STEM analysis at sub-nanoscales, XRD fine scans, and XAS analysis provided evidence of Pb incorporation into the crystal structures of hematite nanoparticles, in which Pb distributed along the zone axis and enlarged the lattice distance of hematite. These results advanced our understanding of the dynamic interactions of Pb with iron oxides by offering new perspectives about the critical roles of chemical speciation, nano-scale spatial distribution, and atomic coordination environments in controlling the geochemical dynamics of heavy metals.

Background Many chronic metabolic diseases, such as obesity and type 2 diabetes (T2DM), are closely related to a chronic low-grade inflammatory state in tissues. The high prevalence of non-alcoholic fatty liver disease (NAFLD) in patients with T2DM is related to the role of inflammation in the disease. In this study, we investigated the role of liraglutide in improving lipid metabolism disorders and preventing their progression to NAFLD by modulating inflammatory signaling pathways, thereby providing new treatment options for NAFLD. Methods We designed a 2×2 factorial analysis experiment. A mouse model of NAFLD with T2DM was established by feeding the animals a high-fat diet (HFD). The NAFLD mice with HFD-induced diabetes were treated with liraglutide for 10 weeks. Hematoxylin and eosin staining, Oil Red O staining and electron microscopy were used to observe the accumulation of triglycerides in the liver. RT-PCR and Western blotting were used to analyze the expression of α-SMA, IL-1β, TNF-α, NF-κB and the NF-κB inhibitory protein IκB in the liver at the gene and protein levels, respectively. Results Liraglutide reduced the body weight and fasting blood glucose levels of HFD-fed mice. The expression of α-SMA, IL-1β, TNF-α, and NF-κB in the liver of HFD-fed mice was increased at the mRNA and protein levels, but liraglutide treatment decreased the expression of these molecules. The expression of IκB in the liver decreased at the mRNA and protein levels but was upregulated after liraglutide treatment. Conclusion Based on the current findings, liraglutide can significantly improve hepatic steatosis, primarily by downregulating the expression of inflammatory signaling mediators in the TNF-α pathway.

Background Liraglutide reduces blood glucose, body weight and blood lipid levels. Hormone-sensitive lipase (HSL) is a key enzyme in lipolysis. Evidence from our and other studies have demonstrated that adenylate cyclase 3 (AC3) is associated with obesity and can be upregulated by liraglutide in obese mice. In the present study, we investigated whether hepatic HSL activity is regulated by liraglutide and characterized the effect of liraglutide in the AC3/protein kinase A (PKA)/HSL signalling pathway. Methods Obese mice or their lean littermates were treated with liraglutide or saline for 8 weeks. Serum was collected for the measurement of insulin and lipids. We investigated hepatic AC3, HSL and phosphorylated HSL Ser-660 (p-HSL(S660)) protein expression levels andAC3 and HSL mRNA expression levels and cyclic adenosine monophosphate (cAMP), PKA activity in liver tissue. Results Liraglutide treatment decreased triglycerides (TGs) and free fatty acids (FFAs), increased glycerol, and upregulated hepatic AC3 and p-HSL(s660) levels and cAMP and PKA activities. Conclusion The results suggest that liraglutide can upregulates AC3/PKA/HSL pathway and may promotes lipolysis.

The fractionation of humic substances (HS) at the mineral and water interface can change the constituents and reactivity of HS, but there is still a lack of the understanding of the effects of HS fractionation on the binding characteristics of heavy metals to HS. In this study, the binding characteristics of five heavy metals (Cd, Cu, Ni, Pb, and Zn) to humic acid (HA) before and after adsorption by ferrihydrite were investigated by employing two-dimensional correlation spectroscopy (2D COS) integrated with synchronous fluorescence and Fourier transform infrared (FTIR) spectroscopies. 2D COS analyses of the fluorescence results indicated that the susceptibility of the fluorescence of humic-like fraction to heavy metals significantly decreased after the adsorption of HA by ferrihydrite, which may be due to the fact that humic-like components were preferentially adsorbed by ferrihydrite. However, the fractionation processes did not alter the metal binding sequence and affinity to different HA components. 2D COS analyses of the FTIR results suggested that fractionation processes decreased the susceptibility of COO- groups to heavy metals, and changed the metal binding sequence to polysaccharides C-O and aryl groups, with the exception of Pb. Furthermore, model calculations showed that the binding ability of heavy metals to both humic-like and fulvic-like fractions decreased after the adsorption of HA by ferrihydrite. The results of this study contribute to predicting heavy metal behavior in the environment.

Hydroxyl radical ( OH) is the most powerful reactive oxygen species that plays a critical role in the redox transformation of elements and contaminants. While recent advances have recognized the dark production of hydroxyl radical ( OH) from oxygenation of natural waters and subsurface sediments at anoxic-oxic interfaces, much less is known regarding the dark production of OH from river sediments, the important component in environments. In this study, we collected 22 polluted river sediments spanning a large gradient and area along the main stem of Maozhou river watershed of southern China. Using a combination of field measurements, bench-scale experiments, and complementary characterization techniques, we provided robust evidence that the transportation of river sediment from anoxic to oxic conditions triggered the extensive production of OH. The cumulative OH concentrations produced within 48 h across all sediments ranged from 57 to 1479 μmol/kg (or 88–2294 μM in sediment pore water), much higher than those reported previously from subsurface sediments and anoxic waters. Sediment Fe(II) is the main contributor to OH production, although organic carbon may also contribute to a degree. Because river sediments contained abundant Fe(II) and organic carbon, and the anoxic-oxic interfaces are ubiquitous in river sediments, we expect that the extensive dark production of OH from oxygenation of river sediments is widespread and represents a previously under-appreciated source of OH production. Findings of this study provide novel insights for the understanding of carbon cycling and micropollutant fate, which are valuable for designing efficient sediment remediation strategies.

Soil organic matter (SOM) is a key soil sorbent with a large number of reactive binding sites that may complex with metals, controlling their fate, transport, and bioavailability in soil. However, due to the complex and heterogeneous nature of SOM, it is not easy to probe its physical and chemical properties at the molecular level. In this study, an a priori method was developed to predict the molecular properties of SOM, which incorporated computational molecular modeling, SPARC Performs Automated Reasoning in Chemistry's (SPARC's) chemical reactivity models, and linear free energy relationships (LFERs). Specifically, the method uses SOM models simulated by molecular dynamics modeling based on the experimental elemental composition and functional group information of SOM. For the molecular characteristics, the molecular H/C and O/C ratios, molecular weight, aromatic index, and double bond equivalence of the SOM molecules were calculated. For the proton binding constants, the SPARC was used to calculate the microscopic pKa values of every binding sites of individual molecules of the SOM model. Based on the pKa values, the metal binding constants for individual monodentate binding sites were calculated using the Irving-Rossotti LFERs for different heavy metals. The results agreed reasonably with the default values used in the Windermere Humic Aqueous Model (WHAM) (VI) for the investigated metals. The theoretical SOM models, to some extent, represented the average properties of the investigated SOM. Overall, this study gives new quantitative and molecular insight into the structure and chemical properties of SOM. Detailed deprotonation and metal-SOM complexation information was gained for individual SOM binding sites. Such feasible and straightforward predictive scheme is useful to assess the risk of heavy metals in various aquatic and terrestrial environment involving heterogeneous natural organic matter.

Arsenate [As(V)] soil contamination is a great concern worldwide because of its high toxicity, carcinogenicity, and mobility. The adsorption of As(V) on soil minerals such as ferrihydrite and δ-MnO₂ controls the transport and bioavailability of As(V) in the soil environment. A large number of studies have investigated the equilibrium and mechanisms of As(V) adsorption onto ferrihydrite and δ-MnO₂ individually. However, both ferrihydrite and δ-MnO₂, commonly coexisting within soils has been overlooked and little information is available for the kinetics of As(V) adsorption and desorption in this mixed mineral system. Therefore, in this work, kinetics of As(V) adsorption and desorption onto ferrihydrite and δ-MnO₂ mixed minerals is studied using the stirred-flow method. A kinetics model for the mixed mineral system was developed using the component additivity approach, which incorporated the nonlinear binding of As(V) to both ferrihydrite and δ-MnO₂ simultaneously. The kinetics model successfully predicted the kinetics of As(V) adsorption and desorption in the mixed mineral system under varying solution chemistry conditions and properly accounted for the heterogeneity of the binding sites of both ferrihydrite and δ-MnO₂. For As(V) adsorption kinetics, the ferrihydrite bidentate non-protonated sites (Fh-bi-np) played a dominant role, followed by the δ-MnO₂ binding sites and the ferrihydrite bidentate protonated sites (Fh-bi-p). After the 4-h desorption, As(V) was mainly retained on ferrihydrite binding sites. This study helps to quantitatively elucidate the kinetic behavior and mechanisms of As(V) in the Fe oxide and Mn oxide systems, thus enhancing our understanding of the fate and transport of As in soil environments.

Due to catch-up growth (CUG), there are adverse effects on human health. However, there is little information about its influence on bone metabolism. This study aimed to investigate the effects of leptin on bone metabolism and formation during high-fat diet (HFD)-induced CUG. We randomly divided male Wistar rats (5 weeks old) into four groups: control (CTL), caloric restriction and normal chow (RN), caloric restriction (4 weeks), and HFD (RH), and RH + leptin antagonist (RH + LEPA). We monitored body weights, biochemical markers, and epididymal and perirenal fat in these rats. We then performed Hematoxylin and Eosin (H&E) staining to evaluate bone metabolism. We detected osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa b ligand (RANKL) by qRT-PCR and immunohistochemistry (IHC). We found that HFD increased the body weights in rats. In RN, RH, and RH + LEPA groups, major biochemical markers of bone metabolism in rat serum were significantly altered. We found that epididymal and perirenal fat tissues of RH and RH + LEPA groups were higher than those in the RN group. Severe bone formation impairment in the distal diaphysis and metaphysis of the left femora and lumbar vertebra was seen in the RH group compared to RN, which was even aggravated by a leptin antagonist. OPG in the left femora and lumbar vertebra was lower in RH than the RN group. The leptin antagonist decreased OPG during CUG in the RH group, whereas RANKL expression showed an opposite alteration. During HFD-induced CUG, bone formation was mediated by OPG and RANKL and was affected by the leptin content.

The properties and composition of soil dissolved organic matter (DOM) are highly affected by the adsorption and desorption of organic matter (OM) on soil minerals and heterotrophic microbial respiration. Organic acids (e.g., oxalic acid), components of root exudates, have been revealed to liberate organic matter (OM) by the dissolution of protective mineral phases and stimulate microbial degradation of OM. However, the effects of organic acids on the properties and composition of soil DOM molecules and the related mechanisms are still poorly understood. In this study, we conducted microcosm incubation experiments with and without oxalic acid addition, and aimed to elucidate the variations of DOM properties and composition, employing a combination of Fourier transform ion cyclotron resonance mass spectrometry, optical spectroscopy, and bacterial community composition analysis. Our results indicated that the released OM from the direct dissolution of protective mineral phases by oxalic acid further stimulated the microbial reductive release of Fe mineral-associated OM under anoxic conditions. Furthermore, the addition of oxalic acid enhanced the degradation of aliphatic compounds and lignins with low O/C ratios, and increased the accumulation of lignins with high O/C ratios, tannins, and condensed aromatics. Linking the bacterial community composition to DOM molecular properties and composition further suggested that the enhanced reductive release of Fe mineral-associated OM was highly related to the increased abundances of Proteobacteria and Actinobacteria. Overall, oxalic acid induced long-lasting impacts on soil DOM properties and composition under anoxic soil conditions in our study. We expect that our results will contribute to understanding the dynamics of soil DOM molecules in the environment.

Humic acids (HAs) are redox-active and can serve as either electron acceptors or electron donors to participate in multiple redox reactions. In nature water, HA can be intimately associated with di...

Sorptive fractionation of organic matter (OM) at mineral–water interfaces alters the composition of OM and therefore affects the fate, transport, and bioavailability of nutrients and contaminants in terrestrial and aquatic environments. It is essential to identify the fractions of OM that are selectively sorbed on minerals and to elucidate the mechanisms of sorptive fractionation. In this study, the partition between mineral and water for a large set of organic molecules covering the most relevant OM functional groups and building blocks were predicted using the mechanistic Polyparameter Linear Free Energy Relationships (pp-LFERs). The results were used to infer the sorptive fractionation tendency of OM moieties. It is found that for a OM moiety belonging to the chemical classes of alkanes, alkenes, or benzenes, its sorption to bentonite is the strongest, followed by kaolinite, talc or hematite, and Al₂O₃ or quartz, relative to water. For a moiety with either double bond, or –OH, or –COOH, or R–COO–R′, or R–O–R′, or R–COH, or R–CO–R′, or –NH₂, its partition to water is enhanced as compared to the respective alkane moiety. Opposite is found for thiols and sulfides. Meanwhile, a correlation is developed, that is, as the double bond equivalence decreases and the number of C atoms increases, the degree of sorption increases. Overall, the key factors controlling the sorptive fractionation are polarity, H-bonding, van de Waals dispersion, and the energy for cavity formation. This work provides insights into the OM sorption at the mineral and water interface at the molecular level.

Allophane, a nano-size alumino-silicate mineral, has a peculiar hollow and spherical nanostructure with diameters of 3.5–5 nm and some defects or open pores. The adsorptive fractionation of dissolved organic matter (DOM) within allophane nanostructures is a key soil process affecting carbon cycling in soil environments, but the underlying mechanisms are poorly understood. In this study, we employed both double spherical-aberration-corrected scanning transmission electron microscopy (Cs-STEM) and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to elucidate the spatial distribution of DOM on allophane at sub-nanoscales and the mechanisms controlling the adsorptive fractionation of DOM molecules. Copper titration experiments and WHAM 7 were used to assess the role of carboxylic groups in the fractionation of DOM on allophane. Cs-STEM results revealed that within allophane aggregates, C mainly distributed on the edges of the pore spaces between allophane aggregates while some DOM molecules localized at some small pore spaces. Moreover, the Cs-STEM results suggested that DOM molecules were able to enter the interior spaces within tiny allophane nanoparticles/aggregates. FT-ICR-MS analysis indicated that molecules with high aromaticity, oxygen numbers and amounts of COO groups were preferentially adsorbed. The results of Cu titration and WHAM 7 calculations indicated that the carboxylic functional groups of DOM were selectively removed from solutions during adsorptive fractionation. Overall, both chemical adsorption and physical isolation may be responsible for the strong sequestration of DOM molecules on allophane. Our results contribute to prediction of C cycling in the environment.

Prediction of adsorption equilibrium coefficients (K) of organic compounds onto single walled carbon nanotubes (SWNTs) from in silico molecular descriptors is of importance for probing potential applications of SWNTs as well as for evaluating environmental behavior and ecological risks of organic pollutants and SWNTs. In this study, two models for predicting logK were developed with multiple linear regression (MLR) and support vector machine (SVM) algorithms. The two models have satisfactory goodness-of-fit, robustness and predictive ability, and the SVM model performs slightly better than the MLR model. The two models are based on the up-to-date experimental dataset consisting of 61 logK values, and the applicability domains cover diverse organic compounds with functional groups > CC CO, COOH, C(O)O, OH, O, F, Cl, Br, NH2, NH, >N, >NN NC(O)NH2, >NC(O)NH, S and S(O)(O). The adsorption of organic compounds toward SWNTs is mainly determined by van der Waals forces and hydrophobic interactions. Since only in silico molecular descriptors were employed for the modeling, the developed models are beneficial for prediction purposes.

Predicting the kinetics of heavy metal adsorption and desorption in soil requires consideration of multiple heterogeneous soil binding sites and variations of reaction chemistry conditions. Although chemical speciation models have been developed for predicting the equilibrium of metal adsorption on soil organic matter (SOM) and important mineral phases (e.g. Fe and Al (hydr)oxides), there is still a lack of modeling tools for predicting the kinetics of metal adsorption and desorption reactions in soil. In this study, we developed a unified model for the kinetics of heavy metal adsorption and desorption in soil based on the equilibrium models WHAM 7 and CD-MUSIC, which specifically consider metal kinetic reactions with multiple binding sites of SOM and soil minerals simultaneously. For each specific binding site, metal adsorption and desorption rate coefficients were constrained by the local equilibrium partition coefficients predicted by WHAM 7 or CD-MUSIC, and, for each metal, the desorption rate coefficients of various binding sites were constrained by their metal binding constants with those sites. The model had only one fitting parameter for each soil binding phase, and all other parameters were derived from WHAM 7 and CD-MUSIC. A stirred-flow method was used to study the kinetics of Cd, Cu, Ni, Pb, and Zn adsorption and desorption in multiple soils under various pH and metal concentrations, and the model successfully reproduced most of the kinetic data. We quantitatively elucidated the significance of different soil components and important soil binding sites during the adsorption and desorption kinetic processes. Our model has provided a theoretical framework to predict metal adsorption and desorption kinetics, which can be further used to predict the dynamic behavior of heavy metals in soil under various natural conditions by coupling other important soil processes.

The kinetics of Cd(ii) adsorption/desorption on ferrihydrite is an important process affecting the fate, transport, and bioavailability of Cd(ii) in the environment, which was rarely systematically studied and understood at quantitative levels. In this work, a combination of stirred-flow kinetic experiments, batch adsorption equilibrium experiments, high-resolution transmission electron microscopy (HR-TEM), and mechanistic kinetic modeling were used to study the kinetic behaviors of Cd(ii) adsorption/desorption on ferrihydrite. HR-TEM images showed the open, loose, and sponge-like structure of ferrihydrite. The batch adsorption equilibrium experiments revealed that higher pH and initial metal concentration increased Cd(ii) adsorption on ferrihydrite. The stirred-flow kinetic results demonstrated the increased adsorption rate and capacity as a result of the increased pH, influent concentration, and ferrihydrite concentration. The mechanistic kinetic model successfully described the kinetic behaviors of Cd(ii) during the adsorption and desorption stages under various chemistry conditions. The model calculations showed that the adsorption rate coefficients varied as a function of solution chemistry, and the relative contributions of the weak and strong ferrihydrite sites for Cd(ii) binding varied with time at different pH and initial metal concentrations. Our model is able to quantitatively assess the contributions of each individual ferrihydrite binding site to the overall Cd(ii) adsorption/desorption kinetics. This study provided insights into the dynamic behavior of Cd(ii) and a predictive modeling tool for Cd(ii) adsorption/desorption kinetics when ferrihydrite is present, which may be helpful for the risk assessment and management of Cd contaminated sites.

Understanding the effect of ferrihydrite morphology on the kinetic reactions of metals with ferrihydrite is essential for predicting the dynamic behavior of metals in soil. In this study, kinetics of Pb(II) and Cu(II) adsorption and desorption on two types of ferrihydrite, the freshly precipitated gellike ferrihydrite and freeze-dried dense ferrihydrite representing two typical morphologies under extreme soil conditions, were studied. The high-resolution transmission electron microscopy (TEM) images revealed that the gellike ferrihydrite loosely aggregated with open structure, while the dense ferrihydrite compactly aggregated with more consolidated and thicker structure. The energy dispersive spectroscopy (EDS), at the nanometer scale, showed that Pb(II) and Cu(II) distributed evenly on gellike ferrihydrite but localized on dense ferrihydrite after adsorption. The stirred-flow kinetic experiments showed that higher pH and higher influent metal concentrations increased metal adsorption for both types of ferrihydrite. The dense ferrihydrite adsorbed slower and much less metals than gellike ferrihydrite because of less reactive sites. The desorption of heavy metals from ferrihydrite was affected by combined factors of the ferrihydrite morphology, adsorbed metal concentrations, pH, and metal re-adsorption rates. The mechanic kinetics model based on the CD-MUSIC model successfully described the adsorption and desorption kinetics of Pb(II) and Cu(II) on both gellike and dense ferrihydrite under various chemistry conditions. Our model provided quantitative tools for considering the effects of ferrihydrite morphology and heterogeneous binding sites under varying solution chemistry conditions when predicting the dynamic behavior of Pb(II) and Cu(II) in soil environment.

Cr(vi) has posed a serious risk for the environment and human beings because of its pollution and toxicity. It is essential to understand the equilibrium behavior of Cr(vi) in soils. In this study, the adsorption of Cr(vi) on fourteen soils was studied with batch experiments and quantitative modeling. The batch experiments included the adsorption edge and adsorption isotherm experiments, investigating the adsorption of Cr(vi) with varying soil properties, solution pH, and initial Cr(vi) concentrations. The experimental data were then modeled using the surface complexation models in Visual MINTEQ of CD-MUSIC by considering the adsorption of Cr(vi) and ions onto Fe (hydr)oxides and Al (hydr)oxides, and the Stockholm Humic Model and the fixed charge site model by accounting for the adsorption of the cations to soil organic matter and clay, respectively. Particularly, the modeling method of this study introduced an important parameter RO- to account for the amount of soil organic matter irreversibly adsorbed on soil minerals. Overall, the model predicted reasonably well for the equilibrium partition of Cr(vi) under various conditions with a root-mean-square-error of 0.35 for the adsorption edge data and 0.19 for the adsorption isotherm data. According to the model calculations, ferrihydrite dominated the binding of Cr(vi) at pH of 3.0-7.0. The content of ferrihydrite and reactive soil organic matter was found to be the main factor influencing RO-. The modeling results help to understand and predict Cr(vi) adsorption on different soils and are beneficial to environmental risk assessment and pollution remediation.

There is concern about the environmental fate and effects of munition constituents (MCs). Polyparameter linear free energy relationships (pp-LFERs) that employ Abraham solute parameters can aid in evaluating the risk of MCs to the environment. However, poor predictions using pp-LFERs and ABSOLV estimated Abraham solute parameters are found for some key physico-chemical properties. In this work, the Abraham solute parameters are determined using experimental partition coefficients in various solvent-water systems. The compounds investigated include hexahydro-1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), hexahydro-1,3-dinitroso-5- nitro-1,3,5-triazine (DNX), 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), and 4-nitroanisole. The solvents in the solvent-water systems are hexane, dichloromethane, trichloromethane, octanol, and toluene. The only available reported solvent-water partition coefficients are for octanol-water for some of the investigated compounds and they are in good agreement with the experimental measurements from this study. Solvent-water partition coefficients fitted using experimentally derived solute parameters from this study have significantly smaller root mean square errors (RMSE = 0.38) than predictions using ABSOLV estimated solute parameters (RMSE = 3.56) for the investigated compounds. Additionally, the predictions for various physico-chemical properties using the experimentally derived solute parameters agree with available literature reported values with prediction errors within 0.79 log units except for water solubility of RDX and HMX with errors of 1.48 and 2.16 log units respectively. However, predictions using ABSOLV estimated solute parameters have larger prediction errors of up to 7.68 log units. This large discrepancy is probably due to the missing R2NNO2 and R2NNO2 functional groups in the ABSOLV fragment database.

The interactions between soil organic matter (SOM) and minerals are key processes controlling the organic carbon (OC) stability in the environment, but the underlying mechanisms responsible for OC distribution on minerals are still not clear. In this study, a common crystalline iron oxide, hematite, and a typical SOM component, humic acid (HA), were chosen to explore, at the nano and even sub-nano scales, HA adsorption and distribution on hematite under the impact of Pb(II) ions. Adsorption experiments and spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) coupled with energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) demonstrated that Pb(II) enhanced the adsorption of HA on hematite, but the nano scale distributions of HA varied between experimental conditions. The Cs-STEM, EDS, and the EELS analyses clearly unveiled that, with the presence of Pb(II), the hematite aggregates became more dispersed, and HA was not only adsorbed on the edges hematite nanoparticles, but also was localized in the extended areas away from the hematite particles/aggregates, which resulted in a heterogeneous distribution of OC in hematite-HA systems. Our imaging methods provided direct visualization of the mineral-SOM-metal interactions at nano scales, which shed lights on the underlying mechanisms for OC stabilization in natural environments and can enable more robust constraints in the models of organic matter-mineral interactions.

The speciation and mobility of As are controlled by both Fe and Mn (oxyhydr)oxides through a series of surface complexation and redox reactions occurring in the environment, which is also complicated by the solution chemistry conditions. However, there is still a lack of quantitative tools for predicting the coupled kinetic processes of As reactions with Fe and Mn (oxyhydr)oxides. In this study, we developed a quantitative model for the coupled kinetics of As adsorption/desorption and oxidation in ferrihydrite-Mn (oxyhydr)oxides and ferrihydrite-Mn(II)-O2 systems. This model also accounted for the variations in solution chemistry conditions and binding site heterogeneity. Our model suggested that Mn (oxyhydr)oxide and ferrihydrite mainly served as an oxidant and an adsorbent, respectively, when they coexisted. Among the three types of binding sites of ferrihydrite, the adsorbed As(V) was mainly distributed on the nonprotonated bidentate sites. Our model quantitatively showed that the oxidation rates of different reaction systems varied significantly. The rates of As(III) oxidation were enhanced with higher pH values and higher molar ratios of Mn(II)/As(III) in the ferrihydrite-Mn(II)-O2 system. This study provides a modeling framework for predicting the kinetic behavior of As when multiple adsorption/desorption and oxidation reactions are coupled in the environment.

Understanding the kinetics of Ni dissociation from dissolved organic matter (DOM) helps to better predict the fate and bioavailability of Ni ions in the environment. However, there is still a lack of predictive models for the kinetics of Ni dissociation from DOM under different reaction conditions. In this study, kinetics of Ni dissociation from humic acids (HA) and fulvic acids (FA), two most important components in DOM for Ni binding, was studied with a competing ligand exchange method at varying Ni concentrations, reaction pH, and ionic strength. The kinetic data were analyzed using a mechanistic kinetics model developed based on the Windermere Humic Aqueous Model (WHAM). Experimental results showed that Ni dissociation rates were affected by both Ni concentrations and pH, and Ni dissociation from FA had faster rates than that from HA. The kinetics model can reproduce the experimental data well, with only two model fitting parameters for different reaction conditions. The modeling results showed that various HA and FA binding sites played different roles in controlling Ni dissociation rates, with bidentate binding sites and the weak tridentate sites being the most significant. At high pH values the Ni re-association reactions were significant for controlling the overall rates of Ni dissociation but had minimal impact at lower pH values. Our model provided a modeling framework based on WHAM 7 for predicting Ni dissociation rates when humic substances were the dominant binding ligands.

Nicotinamide phosphoribosyltransferase (Nampt) is a key enzyme in the nicotinamide adenine dinucleotide (NAD+) biosynthetic pathway. Exogenous extra cellular Nampt has been reported to increase the synthesis of pro-fibrotic molecules in various types of renal cells. However, the role of endogenous Namptenzymatic activity in diabetic renal cells, particularly those associated with inflammation and fibrosis through the nuclear factor (NF)-κB p65 and sirtuin 1 (Sirt1) pathway is still unknown. In the present study, a possible mechanism by which endogenous Nampt upregulation affects the expression of pro-inflammatory and pro-fibrotic cytokines in vivo and in vitro, is reported. The present results demonstrate that the expression of vimentin and fibronectin was directly implicated in endogenous Nampt upregulation. The expression levels of Poly(ADP-ribose) polymerase-1, NF-κB p65, forkhead box protein O1 and B-cell lymphoma 2-like protein 4 were also significantly increased at 96 h compared with control group (P

A partitioning-based model is presented to estimate the bioconcentration of five munitions compounds and two munition-like compounds in grasses. The model uses polyparameter linear free energy relationships (pp-LFERs) to estimate the partition coefficients between soil organic carbon and interstitial water and between interstitial water and the plant cuticle, a lipid-like plant component. Inputs for the pp-LFERs are a set of numerical descriptors computed from molecular structure only that characterize the molecular properties that determine the interaction with soil organic carbon, interstitial water, and plant cuticle. The model is validated by predicting concentrations measured in the whole plant during independent uptake experiments with a root-mean-square error (log predicted plant concentration-log observed plant concentration) of 0.429. This highlights the dominant role of partitioning between the exposure medium and the plant cuticle in the bioconcentration of these compounds. The pp-LFERs can be used to assess the environmental risk of munitions compounds and munition-like compounds using only their molecular structure as input.

Polyparameter Linear Free Energy Relationships (pp-LFERs), also called Linear Solvation Energy Relationships (LSERs), are used to predict many environmentally significant properties of chemicals. A method is presented for computing the necessary chemical parameters, the Abraham parameters (AP), used by many pp-LFERs. It employs quantum chemical calculations and uses only the chemical's molecular structure. The method computes the Abraham E parameter using density functional theory computed molecular polarizability and the Clausius-Mossotti equation relating the index refraction to the molecular polarizability, estimates the Abraham V as the COSMO calculated molecular volume, and computes the remaining AP S, A, and B jointly with a multiple linear regression using sixty-five solvent-water partition coefficients computed using the quantum mechanical COSMO-SAC solvation model. These solute parameters, referred to as Quantum Chemically estimated Abraham Parameters (QCAP), are further adjusted by fitting to experimentally based APs using QCAP parameters as the independent variables so that they are compatible with existing Abraham pp-LFERs. QCAP and adjusted QCAP for 1827 neutral chemicals are included. For 24 solvent-water systems including octanol-water, predicted log solvent-water partition coefficients using adjusted QCAP have the smallest root-mean-square errors (RMSEs, 0.314-0.602) compared to predictions made using APs estimated using the molecular fragment based method ABSOLV (0.45-0.716). For munition and munition-like compounds, adjusted QCAP has much lower RMSE (0.860) than does ABSOLV (4.45) which essentially fails for these compounds.

Diabetes mellitus is a common endocrinopathy in patients with β-thalassaemia major (β-TM), which is high prevalent in southern China. This study aimed to determine the cause and prevalence of glycaemic disorders in Chinese children with β-TM.In this prospective study, fasting glucose and insulin (FINS) levels were assessed in 267 β-TM and 80 non-TM control children. Homeostatic model assessment (HOMA) and the quantitative insulin sensitivity check index (QUICKI) were evaluated. Iron overload was assessed by serum ferritin (SF), total units of blood transfused and cardiac T2*.β-TM had higher FPG (P 0.001), FINS (P 0.001) and HOMA-IR (P 0.05), but lower QUICKI (P 0.01) than those of controls. The impaired fasting glucose (IFG) was present in 30% of children, whereas 2% had diabetes. The prevalence of IFG in β-TM group was higher in children aged10 years (OR 6.5; 95% CI 3.7-11.4; P 0.001), SF of2500 μg/l (OR 4.8; 95% CI 2.1-11.1; P 0.01), serum ALT levels of50 IU/l (OR 2.1; 95% CI 1.2-3.7; P 0.05) and cardiac T2* of20 ms (OR 3.3; 95% CI 1.7-6.6; P 0. 01). The children on deferiprone (DFP) had a reduced incidence of glycaemic aberrations than those on other chelating agents (OR 0.4; 95% CI 0.23-0.8; P 0.05).Our data suggest that IFG occurred in 30% of β TM children, perhaps due to insulin resistance secondary to iron overload. Deferiprone-containing chelating agent may have a protective effect.

The interactions between organic matter (OM) and minerals are among the most important environmental processes, which significantly affect the fate of carbon and contaminants in the environment. How the interactions between OM and ferrihydrite (Fh), one of the most reactive iron oxides, affect the kinetic reactions of heavy metals with both OM and iron oxides, however, are still largely unknown. In this study, two typical OM, humic acids (HA) and fulvic acids (FA), were used to synthesize OM-Fh co-precipitation composites. We investigated the interactions between OM and ferrihydrite and their impact on kinetic reactions of nickel (Ni) with OM-Fh composites using spherical aberration corrected scanning transmission electron microscopy (Cs-STEM), batch and kinetic experiments, and X-ray adsorption spectroscopy (XAS). Cs-STEM results, at both nano and sub-nano scales, showed three typical distributions of OM on ferrihydrite, adsorbed on ferrihydrite surfaces, accumulated as OM nanoparticles, and being blocked in tiny pores in composites. Batch experiments and modeling quantified the effects of OM and ferrihydrite interactions, which was supported by XAS results. The kinetics model developed in this study integrated both WHAM 7 and CD-MUSIC models and successfully predicted the kinetics of Ni adsorption and desorption on OM-Fh composites under the impact of OM-Fh interactions. The model can quantitatively assess the dynamic changes of Ni speciation on different OM and Fh binding sites during the kinetic processes. Our results contribute to developing a comprehensive model for predicting the dynamic metal behavior in the environment when multiple adsorbents are present.

The aim of the study was to investigate the expression of MIP-1 alpha and sclerostin in bone marrow of patients with multiple myeloma (MM), the possible association of the sclerostin and MIP-1 alpha with MBD and the clinical characteristics. 53 patients (29 M, 24 F), median age 64 years was studied. MIP-1 alpha, sclerostin and bone-specific alkaline phosphatase (bALP) levels were quantified using an enzyme-linked immunosorbent assay (ELISA). Sclerostin and MIP-1 alpha mRNA expression was determined by RT-PCR. PTH and 1,25(OH) 2D3 levels were measured with an electrochemiluminescence immunoassay. The sclerostin and MIP-1 alpha concentrations in patients with MM were higher than those in the controls. RT-PCR analysis verified that the bone marrow mononuclear cells (BMMNCs) of most patients showed sclerostin and MIP-1 alpha mRNA expression. The sclerostin and MIP-1 alpha levels in patients with ISS stage III disease were significantly higher than those in patients with ISS stage II disease (p=0.01 and 0.06). The sclerostin and MIP-1 alpha levels in patients with BMD in group C were significantly higher than those in group A+B. There was positive correlation between sclerostin levels and MIP-1 alpha, beta2-microglobulin and aCa levels. A negative association was seen between sclerostin levels and bALP, HB and ALB levels. The MM patients with high sclerostin levels (>0.72 ng/ml) had significantly shorter median survival than those with low sclerostin levels (≤0.72 ng/ml) (χ(2)=7.574, p=0.006). Our findings support the positive relationship between sclerostin levels and MIP-1alpha levels deserve further detailed research.

Early detection of liver fibrosis in thalassemia patients and rapid initiation of treatment to interfere with its progression are extremely important.This study aimed to find a sensitive, easy-to-detect and noninvasive method other than liver biopsy for early detection of liver fibrosis in thalassemia patients.A total of 244 Chinese Thalassemia patients with non-transfusion-dependent thalassemia (NTDT,Serum C IV, PIIINPC and HA were significantly elevated in Chinese patients with NTDT and further elevated in TM patients. Moreover, C IV, PIIINPC and HA were also positively correlated to serum ferritin and liver iron concentration and further elevated during the progression to multi-organ damage in NTDT patients. Finally, serum ferritin and liver iron concentration were significantly correlated with liver dysfunction determined by AST and ALT.Taken together, our results indicate that monitoring serum C IV, PIIINPC and HA is a potentially sensitive method to predict the risks for iron overload-related liver fibrosis in Chinese thalassemia patients.

The roles of NF-kappaB (NF-kappaB) expression, Bax activity and cytochrome C (Cyt C) release, apoptosis of islet cells induced by high concentration glucose were explored in vitro. Pancreatic islet cells, which were isolated from Kunming mice, were cultured with different concentrations of glucose in DMEM, and divided into the following groups: G1, G2, G3, G4, G5, and G6 groups, corresponding to the glucose concentrations of 5.6, 7.8, 11.1, 16.7, 22.5, and 27.6 mmol/L, respectively. After culture for 120 h, insulin secretion was evaluated by radioimmunoassay, and the NF-kappaB expression was detected by immunocytochemistry. Bax activity and Cyt C release were measured by immunofluorescence, and apoptosis was examined by Hoechst33342 assay. The results showed that in G1, G2 and G3 groups, insulin secretion was enhanced with the increase of glucose concentration, and the NF-kappaB expression was also increased (P0.05), but Bax activity, Cyt C release and apoptosis rate showed no significant difference among them. However, in G4, G5, and G6 groups, apoptosis rate of islet cells, NF-kappaB expression, Bax activity, and Cyt C release were all significantly increased, and insulin secretion was impaired as compared with G1, G2, and G3 groups (P0.05). It was concluded that the exposure of islet cells to high glucose could induce islet cells apoptosis as well as impaired insulin secretion. The NF-kappaB signaling pathway and mitochondria pathway in islet cells might play some roles in the progressive loss of islet cells in diabetes. The inhibition of the NF-kappaB expression could be an effective strategy for protecting pancreatic islet cells.