Abstract  The influence of different additions (dry powders or solutions of compounds industrially available) on the early hydration kinetics of ordinary Portland cement is investigated by isothermal calorimetry. The results establish that the additions of Master X-SEED100, calcium nitrate tetrahydrate, calcium chloride and a synthetic solution of hydrated Portland cement can highly accelerate, even at low concentration, the hydration kinetics of Portland cement. Using higher weight ratios, fumed silica, titanium dioxide and precipitated calcium carbonate accelerate moderately the hydration. Moreover, the nanoparticles made of iron or iron oxide and the activated charcoal filler do not show any accelerating effect. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  The mechanisms and ionic product distributions related to multiple channels of the X- + CH3ONO2 (X = NCCH2, CH3C(O)CH2, and PhCH2) gas phase reactions were investigated at the B2PLYP/6-311+ G(3df,2p)//MP2/6-31 + G(d,p) level of theory. The reaction channels are bimolecular nucleophilic displacements at either the carbon (S(N)2@C) or nitrogen (S(N)2@N) centers and a proton abstraction followed by dissociation (Eco(2)). For the ambident NCCH2- and CH3C(O)CH2- nucleophiles, two additional pathways for each reaction channel become available through attacks via the methylenic carbon or nitrogen/oxygen centers. The large number of reaction channels for these ambident nudeophiles precludes the unique determination of the Eco2:S(N)2@C:S(N)2@N ratios and of the carbon or nitrogen/oxygen regioselectivity by mass spectrometry measurements. Thus, the relevance of performing detailed, accurate and reliable computational modeling, including determination of unimolecular rate constants with the RRKM theory. The nucleophilic displacements have the largest rate constants, which are: S(N)2@C for the NCCH2- and CH3C(O)CH2- nucleophiles via methylenic carbon and oxygen centers attacks, respectively, and S(N)2@N for the PhCH2- anion. The ionic products distributions 10:82:8, 2:97:1, and 0:18:82 related to the Eco(2):S(N)2@C:S(N)2@N reaction pathways were calculated for the reactions with NCCH2-, CH3C(O)CH2-, and PhCH2-, respectively, which are in excellent quantitative agreement with the experimental data. These agreements suggest that these reactions with large nucleophiles and/or (de)localized charge have a statistical behavior, unlike the same reaction with smaller and localized charge nucleophiles (F- and OH-). (C) 2016 Elsevier B.V. All rights reserved.

Abstract  This work reports an electrochemical sensor for the nitrite determination by using flow injection amperometry (FI-amp) based on a screen printed carbon electrode (SPCE) modified with silver microcubics-polyacrylic acid/poly vinyl alcohol (AgMCs-PAA/PVA). The AgMCs-PAA was synthesized via a simple chemical reduction method. The prepared AgMCs-PAA/PVA modified SPCE displayed excellent electrocatalytic properties for the oxidation of nitrite and increased the catalytic current response. Under the optimum conditions, the sensitivity of the AgMCs-PAA/PVA/SPCE was 1.6, 4.9 and 1.2 times higher than the bare SPCE, PVA/SPCE, and Ag/PVA/SPCE, respectively. This sensor exhibited a rapid amperometric response to the oxidation of nitrite, which allowed it to be used for the determination of nitrite with a linear range from 2.0 mu M to 800.0 mu M with a limit of detection and a limit of quantification of 4.5 and 14.9 mu M, respectively. This propose nitrite sensor had a high sensitivity (474.14 mu AmM(-1)cm(-2)), good repeatability (RSD <6%, n = 6), stability (RSD = 3%, n = 120) and good accuracy (recovery = 84 +/- 3 to 102 +/- 1%). This method successfully detected nitrite in meat products and the results were consistent with those obtained with the standard spectrometer method. It is possible to apply the proposed method to detect nitrite in other foods and in the environment. (C) 2017 Elsevier Ltd. All rights reserved.

Abstract  A series of Cu-x-Ce0.5-x-Zr-0.5 oxides catalysts with different Cu/Ce ratio were synthesized by citric acid method. The catalysts were characterized by XRD, BET surface area, H-2-TPR, NH3-TPD, NO-TPD, XPS and in-situ DRIFTS. The synergistic effect between copper and cerium on the catalytic performance of Cu-x-Ce0.5-x-Zr-0.5 for selective catalytic reduction of NO with ammonia was investigated. It was found that the Cu-0.2-Ce-0.3-Zr-0.5 catalyst show the excellent SCR activity, N-2 selectivity and H2O/SO2 durability in a low temperature range of 150-270 degrees C even at high gas hourly space velocity of 84,000h(-1). The strong interaction leads to the improvement of the acidity and the increase in the amount of active oxygen species (oxygen vacancy), which are responsible for the higher activity at low temperatures. The SCR reaction process over Cu-0.2-Ce-0.3-Zr-0.5 was also examined using in-situ DRIFTS. The DRIFTS results indicate that abundant ionic NH4+ (Bronsted acid sites), coordinated NH3 on the Lewis acid sites, as well as highly active monodentate nitrate and bridging nitrate species were the key intermediates in the SCR reaction. (C) 2017 Elsevier B.V. All rights reserved.

Abstract  Aluminum hydroxide was crystallized in a sodium aluminate solution as bayerite at room temperature. Primary particles appeared as conical pyramids. They were born on particles of alpha-Al2O3 which had been preformed on a surface of FeCrAl alloy mesh as a result of its annealing. The primary nucleation was discussed using a two-step model that consists of a formation of prenucleation clusters and their transformation into nuclei. The induction period is an inversely proportional function to a square of the substrate surface and depends on its nature. Stirring the solution affected the primary nucleation preventing the formation of the prenucleation clusters. At an early stage, in a supersaturated state, the lateral surface of the primary pyramids grew via filling kink sites and forming the secondary pyramids. The secondary pyramids appeared from the prenucleation clusters. The pyramid base grew by a screw mechanism with an unwinding spiral. When a supersaturate degree of the solution decreased, the lateral surface grew by filling kink sites only, whereas the screw mechanism transformed into a usual modification of the screw mechanism with the shrinking spiral. The change in the growth mechanism transformed the primary cone-shaped particles into the final needle-shape particles.

Abstract  For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have been performed for the PAO superstructure to evaluate its performance for heat storage and transfer media.

Abstract  Magnesium Oxide (MgO) based material have been widely used as catalyst, paints, flame retardants, semiconductors, additives in refractory and solid adsorbent. Morphology of a particle has significant influence towards their application. MgO particles were prepared from Magnesium Acetate (MgAc) and Magnesium Nitrate (MgN) precursors using ultrasonic spray pyrolysis method (SP). The MgO particles were characterized by thermogravimetry analysis (TGA), X-Ray Diffraction Analysis (XRD), Field Emission-Secondary Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM). This experimental study results each precursor could have more than one morphologies. It also suggests that the morphology of the MgO particles were controlled by the selection of the precursor, each precursor possess different particle formation characteristic, including the different crystallization rate and also related from the different decomposition behavior during the heating process of SP.

Abstract  Coronary artery disease is the leading cause of mortality in the United States and can result in significant morbidity. In particular, stable ischemic heart disease (SIHD) is a condition that affects nearly 9 million individuals in the United States alone, with substantial annual health care costs related to recurrent medical visits and chronic disease management. Nitrates form a cornerstone of SIHD management by reducing myocardial oxygen consumption and increasing exercise capacity by several mechanisms, including increasing epicardial blood flow through vasodilation and decreased vascular resistance, blunting coronary steal, and reducing preload. Yet the role of nitrates may be underappreciated in clinical practice and their utilization may be limited due to concerns of tolerance to treatment, a lack of randomized data validating their ability to prevent adverse cardiovascular events, and the pervasive use of percutaneous interventions without robust attempts at implementing optimal medical therapy. In this review, we discuss both the recent ACC/AHA/ACP/AATS/PCNA/SCAI/STS and European Society of Cardiology guidelines, with a particular focus on indications, contraindications, and future directions of nitrate therapy in SIHD.

Abstract  Polycrystalline nickel-zinc nanoferrite with composition Ni0.5Zn0.5Fe2O4 has been prepared through the nitrate-citrate gel autocombustion method. The as-prepared powders have been annealed at temperatures of 800, 900 and 1000 degrees C for 4 h and characterized for spinel phase using X-ray diffraction. Pelleted and toroidal samples of Ni0.5Zn0.5Fe2O4 have been sintered at the above temperatures for 4 h in air atmosphere followed by natural cooling to room temperature. Surface morphology of the annealed powders has been recorded using scanning electron microscope. Scanning electron micrographs of the annealed powders display the presence of nearly agglomerated spherical nanoparticles. Temperature variation of the DC electrical resistivity of sintered pellets has been studied in the temperature range of room temperature to 150 degrees C. The electrical resistivity of the samples in the present study is observed to be larger than those for the nickel-zinc ferrites prepared through conventional ceramic process, for all temperatures of sintering. Such ferrite materials with high resistivity can be used as magnetic cores, which are operable over wide frequency range. The initial magnetic permeability of Ni0.5Zn0.5Fe2O4 increases with the increase in sintering temperature. Initial magnetic permeability and dielectric measurements for all samples have been carried out in the frequency range of 1 kHz to 13 MHz.

Abstract  Retrofitting stormwater systems with sensors and controllers will allow cities to be operated as real-time, distributed treatment plants. Unlike static infrastructure, which cannot adapt its operation to individual storms or changing land uses, "smart" stormwater systems will use system-level coordination to maximize watershed pollutant removal and treatment. We illustrate that this vision is not limited by technology, which has matured to the point at which it can be ubiquitously deployed. Rather, the challenge is much more fundamental and rooted in a system-level understanding of environmental science. Once distributed stormwater systems become highly instrumented and controlled, how should they be operated to achieve desired watershed outcomes? The answer to this question demands the development of a theoretical framework for smart stormwater systems. In this paper, we lay out the requirements for such a theory. Acknowledging that the adoption of these systems may still be years away, we also present a modeling framework to allow for the simulation of controlled stormwater systems before they become commonplace. We apply this control framework to two simulated case studies in which stormwater sites are controlled to reduce nitrate loads to downstream water bodies.

Abstract  Two bronze sculptures, Ettore e Andromaca, a reproduction of a plaster model by Giorgio de Chirico, and Cardinale, a cast made from an original by Giacomo Manzu', stand outside the Carlo Bilotti contemporary art museum in Villa Borghese park (Rome). The composition of the artificial brown patina present on the statues' surface, which was applied for aesthetic purposes, is unknown. This paper reports analysis carried out to identify the composition of the artificial patina and describe the corrosion products formed in outdoor conditions. Raman spectroscopy and scanning electron microscopy equipped with X-ray microanalysis were performed on sample fragments and powder scrapings taken from the bronze statues. X-ray powder diffraction was used whenever possible and subject to conservation priorities. Our data revealed, in the artificial brown patina, the formation of copper oxides (cuprite and tenorite) on the surface of both sculptures as possible result of oxidisation treatments performed with a blowtorch before the artificial patination process began. Furthermore, a copper nitrate (gerhardtite) was identified as an ingredient in the preparation applied to the bronze surfaces. The green areas revealed the presence of corrosion products as copper sulphate hydroxide (brochantite) and copper sulphate-chloride (connellite), which form under acid rains conditions.

Abstract  In the stationary field experiment during the years 2012-2014 we monitored the impact of manure and saturation sludge application on the dynamics of inorganic nitrogen forms in the soil and on the sugar beet crop (variety Expert) and we compared it with application of solitary industrial fertilizer.

The results of our experiment confirmed greater dependence of the dynamics of inorganic nitrogen forms in the soil on climate conditions during the growing season compared to its dependence on the applied fertilizers. The differences among the fertilization variants were statistically insignificant. Higher concentrations of inorganic nitrogen were present in the first half of vegetation period. Manure and saturation sludge application enhanced the utilization of nutrients available from soil, which resulted in substantially higher sugar beet crop in variants where this substance had been applied. Moreover, saturation sludge increased the yield by about 12 t.ha(-1) compared with DASA; it has also proved to be an important ameliorating means improving the soil pH.

Abstract  This study was conducted to evaluate the variability of the chemical properties of the soil of an oak forest affected by defoliation and the corresponding microbial abundance. Soil samples were collected from a control zone (zone 1) without outbreaks of defoliating insects and from a sample zone (zone 2) where the trees were affected by Lymantria dispar L. defoliation. The research was conducted to determine the changed conditions for soil microorganisms produced as a consequence of defoliation. The results indicated, by means of analysis of variance (two-way ANOVA, P = 0.05), statistically significant differences (P < 0.0001) with respect to soil hydrolytic acidity, pH, ammonium nitrogen, heterotrophic bacteria, nitrogen fixing bacteria from genus Azotobacter and fungi. The data revealed a low number of heterotrophic bacteria and low pH values in samples taken from the area affected by defoliation. Soils under stands of defoliated trees showed higher values with respect to soil acidity, ammonium nitrogen, fungi and nitrogen fixing bacteria Azotobacter. Moreover, the soil moisture, nitrate nitrogen, organic matter content, organic carbon, the number of heterotrophic bacteria and the number of bacteria from genus Azotobacter exhibited statistically significant seasonal differences between the two zones studied. The correlations between the tested parameters showed that soil parameters such as moisture content, soil acidity, pH, organic matter content, organic carbon, total nitrogen and nitrate nitrogen are important factors influencing the soil populations of aerobic mesophilic heterotrophic bacteria, fungi and nitrogen fixing bacteria in the studied forest ecosystem.

Abstract  Short-term growth dynamics of diatoms were examined by daily sampling and microcosm experiments under in situ environmental conditions in the late rainy season (July) for 10 days and by weekly sampling during summer (June-September) at a fixed point in the Yatsushiro Sea, Japan. During the daily sampling period, a bloom of diatoms such as Skeletonema spp., Thalassiosira spp., and Chaetoceros spp. (> 10(4) cells mL(-1)) occurred in the surface and subsurface layers during the first half of the period, but the population of diatoms declined and sank to the bottom by an average of about 1 m day(-1) during the second half of the observation period. Daily changes in net growth rates of the three dominant diatom genera (ranging from -3.8 to 3.0 day(-1)), which were estimated by daily 24-h microcosm incubations, roughly corresponded with those in ambient cell densities in the surface layer. The relationship between net growth rates and environmental factors suggest that the growth dynamics of diatoms were regulated by irradiance and river discharge (i.e., salinity and phosphate concentration) during the observation period. The field observations using daily microcosm experiments revealed that the maintenance and decline of a diatom bloom on a daily/weekly time scale are controlled by the rapid growth and sinking responses of diatoms following abrupt changes in coastal environments in the Yatsushiro Sea.

Abstract  Perovskites have attracted attention in recent years as an economic alternative to noble metals in oxidation processes. Synthesis conditions of LaCoO3 and LaMnO3 perovskites have been studied varying citrate to nitrate molar ratio in the starting solution, pH and calcination protocol, with the aim of obtaining high purity perovskites, absence of impurities, and with enhanced textural properties. Once synthesis conditions were established, strontium was incorporated in the perovskite lattice as a textural and structural promoter, by substituting lanthanum with different doping levels, i.e. La0.9Sr0.1BO3, La0.8Sr0.2BO3, La0.7Sr0.3BO3, La0.6Sr0.4BO3 and La0.5Sr0.5BO3 with B = Co or Mn. The prepared solids were characterized in terms of crystalline phase identification (XRD), specific surface area (N-2 adsorption-desorption at -196 degrees C), reducibility and oxidation state of transition metal ions (H-2-TPR), quantification of adsorbed oxygen species (O-2-TPD) and surface elemental composition (XPS). Charge imbalance associated to strontium (Sr2+) incorporation in the perovskite lattice in substitution of lanthanum (La3+) was preferentially balanced by Mn4+ promotion in La1-xSrxMnO3 perovskites, whereas formation of oxygen vacancies seems to be the mechanism for charge compensation in La1-xSrxCoO3 perovskites, where Co ions remained as Co3+ ions. Strontium doped perovskites further improved NO conversion compared to the non-substituted formulations. The best NO oxidation performance was obtained with La0.7Sr0.3CoO3 and La0.9Sr0.1MnO3 samples, achieving maximum NO conversion of 83 and 65% at 300 and 325 degrees C, respectively. Higher oxidation capacity of La0.7Sr0.3CoO3 sample was associated to the higher oxygen mobility and exchange capacity between oxygen in the lattice and gas phase oxygen. It is worth noting that prepared perovskites presented far higher NO oxidation capacity than platinum-based NSR model catalysts, confirming perovskites as an economic alternative to catalyze NO oxidation reactions in automotive catalysis. (C) 2017 Elsevier B.V. All rights reserved.

Abstract  Tomatoes are consumed and cultivated all over the world for not only their pleasant taste but also their curative properties. Therefore, the challenge for growers is to obtain high-quality crop productions by developing new varieties of tomatoes or new ecofriendly fertilizers. This study was to test a bone glue-based foliar fertilizer on the tomato crop. The experiment was organized in a vegetation house under an original treatment scheme. Four types of foliar fertilizers were tested: macroelements, microelements and glue; macroelements and glue; microeleements and glue; and macroelements and microelements without glue. The fertilizers were applied as diluted solutions (0.5% and 1%) across three treatments applied on nine variants. The treatments with bone glue-based foliar fertilizer led to a high-quality production of healthy tomatoes, a good absorption of nutrients together with a reduced nitrites level in tomatoes and an increase of agricultural productivity. The applied foliar fertilizers tested on the hybrid tomatoes used in the experiment had a significant positive influence on vegetative growth. The nitrate concentration in the fruit did not exceed the maximum accepted level. The agronomic analysis of the mineral composition of the fruit revealed that foliar fertilizers with glue significantly influenced nutrient assimilation during the treatments. The level of nitrogen (N), phosphorus (P), and potassium (K) recovery following the application of bone glue foliar fertilizers was higher as compared to the control and the variant without bone glue. Biometric measurements had shown significant differences favorable to tomatoes treated with this bone glue foliar fertilizer.

Abstract  Rapid reduction of aqueous ClO4(-) to Cl(-) by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx(-) intermediates formed during reactions with concentrated ClO4(-) promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4(-) reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2(-) intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4(-) reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx(-) scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx(-) intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4(-) reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO4(-). This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications.

Abstract  The zeolitic imidazolate framework ZIF-8 was synthesized through a solvothermal process employing methanol as the solvent, zinc nitrate hexahydrate and 2-methylimidazole as zinc source and organic ligand, re. spectively. The products were characterized by means of XRD, N-2 adsorption, TG-DSC and SEM. In addi. tion, selective adsorption performance for n-hexane on ZIF-8 was investigated. It is indicated that synthesized ZIF-8 has the sodalite crystal structure and a high crystallinity. From the N-2 adsorption results, ZIF-8 product has a pore size range of 0-4-1-1 nm, BET specific surface area of 1836 m(2)/g and pore volume of 0-65 cm(3)/g. Both TG-DSC and high-temperature in situ XRD analyses suggest its excellent thermal stability. As the temperature increases from 283 to 313 K, the diffusion coefficient for n-hexane adsorption on ZIF-8 varies from 2-53x10(-12) to 8-88x10(-12) cm(2)/s and diffusion activation energy is evaluated to be 31-11 kJ/mol. At 308 K, the dynamic adsorption capacity and Thomas adsorption rate constant for n-hexane on ZIF-8 are 187-3 mg/g and 2-17x10(-3) mL center dot min(-1) center dot mg(-1), respectively. As compared to 5A molecule sieve, ZIF-8 displays around 100% higher adsorption capacity and almost 70% faster diffusion rate.

Abstract  A distinctive association of rivulariacean-like calcified microfossils is recognized in back-reef lagoon facies on the Bachu-Tazhong Platform in the Lianglitag Formation (Katian Stage, Upper Ordovician) of the Tarim Basin, based on investigation of 4500 thin sections from 35 well drill cores. The genera include Hedstroemia, Ortonella, Zonotrichites, Cayeuxia, and Garwoodia, most of which have features comparable with present-day calcified cyanobacteria such as Rivularia, Calothrix and Dichothrix (Rivulariaceae, Nostocales). A similar association is present in lagoonal and other restricted nearshore shallow-marine carbonate environments during much of the Paleozoic and Mesozoic. This suggests the sustained presence of a rivulariacean-dominated cyanobacterial association characteristic of back-reef/lagoonal environments. At the present-day, uncalcified Rivularia, Calothrix and Dichothrix remain common in back-reef, lagoon, mangrove-swamp, rocky shore, salt-marsh, and saline lake environments. The ability of these cyanobacteria to grow in environments low in inorganic nitrate and phosphate could help to explain this distribution. Cenozoic decline in marine calcified rivulariaceans is attributed to global reduction of seawater carbonate saturation state. The Phanerozoic record of calcified rivulariacean cyanobacteria appears to sensitively reflect long-term variations in the carbonate and nutrient chemistry of marine environments. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  Two unique hybrids based on Wells-Dawson polyoxometalates, [Cu(en) (2)(OH2)](2)[{Cu.en)(2)}{(As2W2W16O61)-W-V-O-VI}]center dot 6H(2)O (1) and (H(2)dap)[Cu(H(2)dap).H2O)(2)][{Cu.dap).H2O)(2)}{As2W17CuO61}]center dot 5H(2)O (2) (en = ethylenediamine and 1,2-dap = 1,2-diaminopropane), have been synthesized hydrothermally by reaction of Na2WO4, NaAsO2 and CuCl2 with 1,2-dap or en, and further characterized by elemental analysis, infrared radiation (IR) spectrophotometry, ultraviolet (UV) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and single crystal X-ray diffraction. In compounds 1 and 2, the emerging building blocks link into new one-dimensional (1D) chain-like Wells-Dawson architectures via two M-O-M (M = Cu/W) and O-Cu-O bridges, which are rarely observed among this arsenotungstate class. The 1D chain-like architectures further extend into 3D supramolecular frameworks through hydrogen bond interactions. They represent the first family of Dawson-type double-bridge arsenotungstate chains built from M-O-M and Cu-L linkers. Compounds 1 and 2 have exhibited electrocatalytic activity toward the reduction of nitrite. Adsorption experiments show that the compounds have the ability to selectively adsorb MB from binary mixed dye solutions (MB and MO and MB and RhB). These compounds still maintain their excellent stability and adsorption properties after several cycles.

Abstract  Nitrite is a common contaminant in drinking water and groundwater with high environmental and health risks. Electrochemical sensing method is a selective and easy technique to detect nitrite in water. In this study, we report a research about a poly(aniline-co-o-aminophenol)-modified glassy carbon electrode (PAOA/GCE) for aqueous nitrite detection. With stable redox activity and conductivity in a wide pH range compared with polyaniline, PAOA is suitable to be used as electrode material in a neutral medium. The PAOA/GCE was prepared by cyclic voltammogram method by electrochemical copolymerization of o-aminophenol and aniline. SEM and FT-IR results proved the formation of PAOA, and the electrode exhibited higher responses toward nitrite oxidation compared with polyaniline-modified GCE and bare GCE. We also studied the impact of scan rate, pH, and temperature on nitrite detection. The PAOA/GCE could be used in a wide pH range from 2 to 8 and used to detect nitrite in the linear range from 5.0 x 10(-6) to 2.0 x 10(-3) M with the detection limit of 2 x 10(-6) M. Its excellent reproducibility, stability, and anti-interference ability make it a promising electrode in detecting aqueous nitrite in drinking water and groundwater.

Abstract  To investigate the feasibility of using corncob charcoal substrate in constructed wetlands, four laboratory-scale vertical flow constructed wetlands (VFCWs) were built. Effluent pollutant (chemical oxygen demand (COD), NH4(+)-N, total phosphorus (TP)) concentrations during the experiment were determined to reveal pollutant removal mechanisms and efficiencies at different stages. In the stable stage, a VFCW using clay ceramisite substrate under aeration attained higher COD (95.1%), and NH4(+)-N (95.1%) removal efficiencies than a VFCW using corncob charcoal substrate (91.5% COD, 91.3% NH4(+)-N) under aeration, but lower TP removal efficiency (clay ceramisite 32.0% and corncob charcoal 40.0%). The VFCW with raw corncob substrate showed stronger COD emissions (maximum concentration 3,108 mg/L) than the corncob charcoal substrate (COD was lower than influent). The VFCW using corncob charcoal substrate performed much better than the VFCW using clay ceramisite substrate under aeration when the C/N ratio was low (C/N = 1.5, TN removal efficiency 36.89%, 4.1% respectively). These results suggest that corncob charcoal is a potential substrate in VFCWs under aeration with a unique self -supplying carbon source property in the denitrification process.

Abstract  To develop simple and sensitive electrocatalytic technique for toxic nitrite determination is significantly important. Electrochemical nitrite sensor has attracted tremendous attention owing to its high sensitivity, selectivity and short response time. Here, we report the highly sensitive nitrite sensor based on poly(diallyldimethylammonium chloride) (PDDA)-coated Fei.833 (OH)(0.5)O-2.5-decorated N-doped graphene (NG) ternary hierarchical nanocomposite (Fe-1.833(OH)(0.5)O-2.5/NG@PDDA). Differing from complicated synthetic routes for the reported ternary systems, the Fe-1.833(OH)(0.5)O-2.5/NG@PDDA composite can be effectively constructed by a facile one-pot hydrothermal method. The electrochemical performance of Fe-1.833 (OH)(0.5)O-2.5/NG@PDDA composite film modified glassy carbon electrode was investigated by cyclic voltammetry and amperometric techniques. The experimental results indicate that synergistic effect of Fe-1.833(OH)(0.5)O-2.5 as catalytic center, NG as conductive platform and PDDA as nitrite adsorbent can significantly enhance the electrochemical response. The fabricated sensor exhibits the excellent analytical performance for nitrite detection linearly over two different concentration ranges, which are from 0.1 to 347 jiM and from 347 to 1275 p,M with a detection limit of 0.027 p.M (S/N=3). The value is very much comparable to the recent literature ones. Moreover, the proposed electrochemical sensor also shows good stability, reproductivity and excellent anti-interference ability against metal ions and electroactive species, and exhibits satisfactory recovery for detecting nitrite in drinking water. (C) 2016 Elsevier B.V. All rights reserved.