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Competitive adsorption between arsenate, extracellular polymeric substances (EPS), phosphate and sulphate and resulting impacts on microbial arsenate reduction was investigated at the water-goethite interface at 10 μM arsenate with Shewanella putrefaciens strain CN-32 at pH 7. Addition of phosphate and S. putrefaciens EPS to 2 g L −1 goethite suspensions increased dissolved arsenate concentrations and enhanced arsenate reduction rates. The half-life of first order kinetics was 343 h without competitive species, whereas adding 50–500 μM phosphate and 0.28 g L −1 EPS decreased half-lives to 141–177 and 223 h, respectively. Phosphate and EPS addition did not increase arsenate reduction rates at 10 and 0.4 L −1 goethite, reflecting stronger effect of arsenate mobilisation induced by microbe-mineral interaction than competitive adsorption, respectively. Addition of 100 μM sulphate did not accelerate arsenate reduction, reflecting its weak competitive adsorption. Moreover, phosphate may slow down but EPS accelerate arsenate reduction in solution. Addition of 300–700 μM phosphate increased half-life of dissolved arsenate reduction in solution from 21.3 to 29.4–32.2 h but the presence of 1.4 g L −1 EPS decreased half-life to 2.2 h. Depending on surface coverage and the nature and concentrations of competitive species, competitive adsorption may enhance arsenate reduction kinetics and cause arsenic mobilisation. [ABSTRACT FROM AUTHOR]

Abstract: Arsenite and arsenate speciation was performed in 121 commercially purchased samples of 12 rice types to understand their relative relevance in rice grain. General effectiveness of a recently developed extraction protocol based on 0.28M nitric acid at 95°C was verified by checking the recovery of total grain arsenic and by comparing arsenic speciation in NIST-CRM-1568a, NMIJ-CRM-7503a and IMEP-107 with certificated and literature values. The arsenic speciation highlights the predominance of arsenite in 115 and dimethylarsinic acid in six samples and common minor components including arsenate, monomethylarsonic acid and two unknown arsenical species. Our data also indicate potential influences of other trace elements on As speciation in rice grain. Averagely, arsenite accounts for 90% of inorganic grain arsenic regardless of geographic origin, rice type, grain size, cultural practice and polish treatment. The high arsenite predominance indicates an elevated toxic effect of arsenic in rice than is perceived to date. [Copyright &y& Elsevier]

Abstract: Wetland soils play a key role for the transformation of heavy metals in forested watersheds, influencing their mobility, and ecotoxicity. Our goal was to investigate the mechanisms of release from solid to solution phase, the mobility, and the transformation of arsenic species in a fen soil. In methanol–water extracts, monomethylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, arsenobetaine, and two unknown organic arsenic species were found with concentrations up to 14ng Asg−1 at the surface horizon. Arsenate is the dominant species at the 0–30cm depth, whereas arsenite predominated at the 30–70cm depth. Only up to 2.2% of total arsenic in fen was extractable with methanol–water. In porewaters, depth gradient spatial variation of arsenic species, pH, redox potentials, and the other chemical parameters along the profile was observed in June together with high proportion of organic arsenic species (up to 1.2μg AsL−1, 70% of total arsenic). Tetramethylarsonium ion and an unknown organic arsenic species were additionally detected in porewaters at deeper horizons. In comparison, the arsenic speciation in porewaters in April was homogeneous with depth and no organic arsenic species were found. Thus, the occurrence of microbial methylation of arsenic in fen was demonstrated for the first time. The 10 times elevated total arsenic concentrations in porewaters in June compared to April were accompanied by elevated concentrations of total iron, lower concentrations of sulfate and the presence of ammonium and phosphate. The low proportion of methanol–water extractable total arsenic suggests a generally low mobility of arsenic in fen soils. The release of arsenic from solid to solution phases in fen is dominantly controlled by dissolution of iron oxides, redox transformation, and methylation of arsenic, driven by microbial activity in the growing season. As a result, increased concentrations of total arsenic and potentially toxic arsenic species in fen porewaters were found in the growing season, suggesting an enhancing risk of arsenic transport of ground- and surface-waters under these conditions. [Copyright &y& Elsevier]

Abstract: TiN films were prepared by ion beam assisted deposition (IBAD) method under different temperatures and ion energies. Microstructure characterization by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning and transmission electron microscopy (SEM and TEM) confirmed that the nitride films were nanocrystalline in size and composed of grains with grain sizes ∼20 nm. Textures of the films were studied by XRD pole figure measurements. Residual stress was determined by the modified sin2 ψ method using grazing incidence XRD. Hardness of the thin films was measured by nanoindentation. It is found that nanoindentation measurement cannot reflect the variation of residual stress. Nanohardness of the samples also displayed insignificant relationship with texture. Since the dislocation activity is retarded due to nanograin structure, the geometrical strengthening via texture control or Hall–Petch relationship is no longer applicable. Therefore, grain rotation or grain boundary sliding may be the deformation mechanisms for nanocrystalline thin film. The contradictory relationships between hardness and preferred orientation were also clarified. [Copyright &y& Elsevier]

TiN, VN and CrN were systematically deposited on silicon substrates using ion beam assisted deposition (IBAD) technique at temperatures and ion (N2+) energy ranging from 300 °C to 500 °C and 100 eV to 650 eV, respectively. The results showed that the texture could be controlled by the ion beam energy, flux, and its incident angle, in conjunction with the deposition temperature. For the 0° angle of ion incidence, fiber textures were formed and could be controlled between (111) and (200) surface plane orientation by adjusting ion flux or ion energy. Three types of in-plane textures were produced, when the ion beam was incident at 45° angle, for which cases ion channeling played an important role in the formation of in-plane texture. Using the strain-energy perturbation method, the stability of texture can be further understood. Among the three in-plane textures, the (200) in-plane texture is strain-energy stable, and the others are not. [Copyright &y& Elsevier]

This research studied the effect of bias on the microstructure and properties of zirconium nitride (ZrN) deposited on Si (1 0 0) and AISI stainless steel 304. The ZrN films were deposited using hollow cathode discharge ion plating (HCD-IP) method. The optimum coating conditions were first determined using Taguchi experimental method. Based on the optimum conditions, the single-variable experiments on the effect of bias were conducted. The cross-sectional microstructure revealed that the columnar structure of the ZrN film became denser with increasing bias. The results of X-ray diffraction (XRD) showed that all the coating samples exhibited (1 1 1) preferred orientation both on Si and SS304 substrates. To avoid substrate effect, the hardness of the ZrN films was measured by nanoindentation. The hardness values of ZrN films deposited on Si were ranged from 27 to 30 GPa, and on stainless steel 304 were from 32.5 to 40.8 GPa. The ZrN films deposited on the stainless steel were very smooth with a roughness number ranging from 1.1 to 3.9 nm. The N:Zr ratios were determined using X-ray photoelectron spectrometry (XPS) and the results indicated that the films were close to the stoichiometric composition. The resistivity of ZrN films gradually decreased with increasing bias until −120 V and then abruptly increased. The corrosion resistance of ZrN-coated stainless steel was evaluated by standard salt spray test and potentiodynamic scanning in two kinds of solution environments: 5% NaCl and 1N H2SO4 +0.05 M KSCN, respectively. The results showed a consistent trend between salt spray test and potentiodynamic scanning. The corrosion resistance increased with bias at bias ranging from 0 to −90 V, then abrupt decreased at −120 V, and then increased again at −150 V. The properties changes of resistivity and corrosion resistance can be explained by the change of film structure due to bias-induced ion bombardment. [Copyright &y& Elsevier]

Measurements of residual stresses in textured thin films have always been problematic. In this article, a new experimental method using grazing-incidence X-ray diffraction is presented with its principles based upon the conventional sin2ψ method. Instead of using the Bragg–Brentano (B-B) or Seemann–Bohlin geometry, the proposed method utilizes an asymmetrical diffraction geometry for which the X-ray beam is incident at a grazing angle γ to the sample surface, while the angle ψ is the tilt angle of the sample surface as defined by the conventional sin2ψ method. Basic equations involved in the X-ray residual stress analysis are described, along with exemplified experimental data. Analysis shows that, for an isotropic medium, strain measured using this grazing-incidence geometry assumes a linear relationship with the geometrical parameter cos2α sin2ψ, where the angle α is a constant and is defined as the Bragg angle at ψ=0°, θo, minus the grazing incidence angle γ, i.e. α=θo−γ. The grazing-incidence diffraction geometry effectively increases the irradiation volume from a thin-film specimen, thereby giving rise to higher intensity for high-angle Bragg peaks than the conventional B-B geometry. The proposed analysis has another advantage, in that the inhomogeneous sample casts little effect on the residual stress results when compared to the traditional sin2ψ method. [Copyright &y& Elsevier]

Abstract: Background: Hypertension induces cardiac dysfunction, calcium (Ca2+) dysregulation, and arrhythmogenesis. Dipeptidyl peptidase (DPP)-4 inhibitors, an antidiabetic agent with anti-inflammation and anti-hypertension potential, may regulate peroxisome proliferator-activated receptors (PPARs)-α, -γ, and -δ and Ca2+ homeostasis. Objective: The purpose of this study was to investigate whether DPP-4 inhibitor, sitagliptin, can modulate PPARs and Ca2+ handling proteins in hypertensive hearts. Methods: A Western blot analysis was used to evaluate protein expressions of myocardial PPAR isoforms, tumor necrosis factor (TNF)-α, interleukin (IL)-6, sarcoplasmic reticulum ATPase (SERCA2a), Na+–Ca2+ exchanger (NCX), ryanodine receptor (RyR), voltage-dependent Ca2+ (CaV1.2), slow-voltage potassium currents (Kvs), angiotensin II type 1 receptor (AT1R), and receptor of advanced glycated end-products (RAGE) from Wistar-Kyoto (WKY) rats, spontaneously hypertensive rats (SHR), and SHR treated with sitagliptin (10mg/kg for 4weeks). Conventional microelectrodes were used to record action potentials (APs) in the ventricular myocytes from each group. Results: Compared to the control group, SHR had lower cardiac PPAR-α and PPAR-δ protein expressions, but had greater cardiac PPAR-γ levels, and TNF-α, IL-6, RAGE, and AT1R protein expressions, which were ameliorated in the sitagliptin-treated SHR. SHR had prolonged QT interval and AP duration with less SERCA2a and RyR, and greater CaV1.2 expressions, which were also attenuated in sitagliptin-treated SHR. Conclusions: Sitagliptin significantly changed the cardiac electrophysiological characteristics and Ca2+ regulation, which may have been caused by its effects on cardiac PPARs, proinflammatory cytokines, and AT1R. [Copyright &y& Elsevier]

Abstract: Cardiovascular disease (CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus (DM). Chronic inflammation and derangement of myocardial energy and lipid homeostasis are common features of DM. The transcription factors of peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily, which are important in regulating energy and lipid homeostasis. There are three PPAR isoforms, α, γ, and δ, and their roles have been increasingly recognized to be important in CVD. These three isoforms are expressed in the heart and play pivotal roles in myocardial lipid metabolism, as well as glucose and energy homeostasis, and contribute to extra metabolic roles with effects on inflammation and oxidative stress. Moreover, regulation of PPARs may have significant effects on cardiac electrical activity and arrhythmogenesis. This review describes the roles of PPARs and their agonists in DM cardiomyopathy, inflammation, and cardiac electrophysiology. [Copyright &y& Elsevier]

Abstract: Organo-Sn, -Pb and -Hg compounds were monitored in gases and leachates of 11 municipal waste landfills and one hazardous waste landfill from Bavaria, Germany, with the objectives to estimate the methylation of Sn, Pb and Hg and to assess the risk of their release into the adjacent environment. In the gases, tetramethyl Sn predominated (>80% of total gaseous Sn) with concentrations up to 160μg Sn m−3. Dimethyl-Hg and tetramethyl-Pb were only occasionally detected with concentrations up to 2.9 and 2.1μgm−3 as Hg or Pb, respectively. In all leachates, trimethyl-Sn dominated with a maximum concentration of 2100ng Sn L−1. No organo-Pb compounds were found, and monomethyl-Hg was detected in only one leachate. The concentrations of trimethyl-Sn were up to 100-fold higher in the condensate water than in leachates, and the concentrations of organo-Sn compounds were lower in the adjacent groundwater than in the corresponding leachates. The high abundance of methylated Sn species in the gases and leachates indicates Sn methylation, suggesting the landfill as a source for organo-Sn compounds. In comparison, methylation of Hg and Pb was of little importance, probably due to low Hg concentrations and low rates of Pb methylation in the landfill. The risks of organo-Sn compounds release to the adjacent air is low due to flaring of landfill gases. However, there is probable release of organo-Sn compounds, especially trimethyl-Sn, to the adjacent groundwater. [Copyright &y& Elsevier]