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  • 1
    Language: English
    In: Applied and environmental microbiology, April 2013, Vol.79(8), pp.2572-7
    Description: Sulfadiazine (SDZ)-degrading bacterial cultures were enriched from the topsoil layer of lysimeters that were formerly treated with manure from pigs medicated with (14)C-labeled SDZ. The loss of about 35% of the applied radioactivity after an incubation period of 3 years was attributed to CO2 release due to mineralization processes in the lysimeters. Microcosm experiments with moist soil and soil slurries originating from these lysimeters confirmed the presumed mineralization potential, and an SDZ-degrading bacterium was isolated. It was identified as Microbacterium lacus, denoted strain SDZm4. During degradation studies with M. lacus strain SDZm4 using pyrimidine-ring labeled SDZ, SDZ disappeared completely but no (14)CO2 was released during 10 days of incubation. The entire applied radioactivity (AR) remained in solution and could be assigned to 2-aminopyrimidine. In contrast, for parallel incubations but with phenyl ring-labeled SDZ, 56% of the AR was released as (14)CO2, 16% was linked to biomass, and 21% remained as dissolved, not yet identified (14)C. Thus, it was shown that M. lacus extensively mineralized and partly assimilated the phenyl moiety of the SDZ molecule while forming equimolar amounts of 2-aminopyrimidine. This partial degradation might be an important step in the complete mineralization of SDZ by soil microorganisms.
    Keywords: Mycobacterium -- Metabolism ; Sulfadiazine -- Metabolism
    ISSN: 00992240
    E-ISSN: 1098-5336
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  • 2
    Language: English
    In: Applied and Environmental Microbiology, April 15, 2013, Vol.79(8), pp.2572-6
    Keywords: Lysimetry – Usage ; Mycobacteria – Research ; Mycobacteria – Physiological Aspects ; Sulfadiazine – Research
    ISSN: 0099-2240
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Chemosphere, Jan, 2014, Vol.95, p.470(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chemosphere.2013.09.100 Byline: Stephan Sittig, Roy Kasteel, Joost Groeneweg, Diana Hofmann, Bjorn Thiele, Stephan Koppchen, Harry Vereecken Abstract: acents We show transformation and sequestration of the antibiotic sulfadiazine in two soils. acents Transformation products were found in liquid phase and extracts from the sorbed phase. acents We used a compartment model including all species and did global optimization. acents Sorption and transformation are concentration dependent. Article History: Received 12 December 2012; Revised 21 September 2013; Accepted 29 September 2013
    Keywords: Soils ; Sulfadiazine
    ISSN: 0045-6535
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: International Journal of Hydrogen Energy, 22 October 2014, Vol.39(31), pp.18027-18036
    Description: The long-term stability at autothermal reforming of diesel fuel and kerosene was studied using Juelich's autothermal reformer ATR 9.2, which is equipped with a commercial proprietary RhPt/Al O –CeO catalyst. The experiment was run for 10,000 h of time on stream at constant reaction conditions with an O /C molar ratio of 0.47, a H O/C molar ratio of 1.9, and a gas hourly space velocity of 30,000 h . Kerosene produced via the gas-to-liquid process and diesel fuel synthesized via the bio-to-liquid route were used. Both fuels were almost free of mass fractions of sulfur and aromatics. The trends for the desired main products of autothermal reforming H , CO, CO , and CH were almost stable when kerosene was used. When the fuel mass flow was switched to diesel fuel however, different modes of catalyst deactivation occurred (active sites blocked by carbonaceous deposits, sintering processes), leading to a decrease in the concentrations of H and CO with a simultaneous increase in the CO content. This paper defines carbon conversion as the decisive criterion for evaluating the long-term stability during autothermal reforming of kerosene and diesel fuel. Carbon conversion was diminished via three different pathways during the long-term experiment. Undesired byproducts found in the gas phase leaving the reactor had the strongest impact on carbon conversion. These byproducts included ethene, propene, and benzene. Furthermore, a liquid oily residue was detected floating on the condensed unconverted mass flow of water. This happened once during the whole experiment. Finally, undesired organic byproducts were dissolved in the mass flow of unconverted water. These were found to be straight-chain and branched paraffins, esters, alcohols, acids, aldehydes, ketones, etc. Nevertheless, at the end of the long-term experiment, carbon conversion still amounted to more than 98.2%.
    Keywords: Autothermal Reforming ; Fuel Processing ; Diesel ; Kerosene ; Fuel Cells ; Auxiliary Power Unit ; Engineering
    ISSN: 0360-3199
    E-ISSN: 1879-3487
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  • 5
    Language: English
    In: The Journal of Physical Chemistry C, 07/07/2016, Vol.120(26), pp.13873-13890
    Description: This study establishes the relationships between the structure of a series of meso-substituted tin(IV) porphyrins and their efficiency as photosensitizers for hydrogen generation in the Sn(IV)P/Pt-TiO2 nanocomposite system. The electrochemical properties of a series of SnPs, the catalytic performance of Pt nanomodifications, and the morphology of the Pt/TiO2 nanocomposites were characterized by electrochemical and electron microscopy methods. The dependence of photocatalytic performance on the structure for a series of Sn(IV) meso-substituted phenyl porphyrins was studied, and possible mechanisms are discussed employing the results of the electrochemical studies. It was found that the time course and type of the photochemically reduced species of Sn(IV)Ps, which are essential intermediates, are important factors and depend on the electronegativity of the metal center, the character of meso-substituents of the porphyrin ring, and pH and are correlated with the redox potential sequence of the respective Sn(IV)Ps: SnTMPyP 〉 SnTPyP 〉 SnTPPS 〉 SnTPPC. Optimization of the experimental parameters was performed with regard to the SnPs with different functional groups, pH values, concentrations of Pt/TiO2, light intensity, and Pt nanoparticles with different surface stabilizers. Finally, the maximum hydrogen yield under visible light was obtained from the system of Sn(IV) meso-tetra(4-pyridyl)porphyrin dichloride (SnTPyP) sensitized TiO2/Pt prepared by the citrate method/EDTA at pH 9.0. This demonstrates that the photochemically reduced species of SnTPyP are relatively long lived, so they have enough time to complete electron transfer to TiO2 and/or Pt. The adsorption of SnTPyP on the TiO2/Pt surface is therefore not essential for hydrogen generation. Moreover, this study demonstrates for the first time the synergic effect of the excitation of TiO2 and mostly Q-bands of Sn(IV)P (wavelength range 390-650 nm), which enhances the efficiency of photocatalytic hydrogen generation in the system. The Soret band of Sn(IV)TPyP was found to produce a minor (about 23%) contribution to the photocatalytic activity of the porphyrin sensitizer in this system. Possible processes involved are discussed, and mechanisms are proposed explaining different aspects of a series of photocatalytic systems with SnPs and Pt catalysts for hydrogen production under visible light. These structure-function relationships are essential to effectively harness solar energy for hydrogen production as well as for a wide range of energy and environmentally related problems.
    Keywords: Porphyrins ; Tio2 ; Nanocrystalline-Composites ; Nanoparticles ; Hydrogen-Evolution ; Hydrogen-Production ; Redox-Potential ; Ph-Number ; Electronegativity ; Electron-Microscopy ; Light-Intensity ; Photosensitizers ; Substituent ; Functional-Group ; Catalytic-Properties ; Electrochemical-Analysis ; Electron-Transition ; Light-Radiation ; Porphyrin ; Titan(IV)-Oxid ; Nanokomposit ; Nanopartikel ; Wasserstoffentwicklung ; Wasserstofferzeugung ; Redox-Potenzial ; Ph-Wert ; Elektronegativität ; Elektronenmikroskopie ; Lichtintensität ; Photosensibilisator ; Substituent ; Funktionelle Gruppe ; Katalytische Eigenschaft ; Elektrochemische Analyse ; Elektronentransfer ; Sichtbares Licht ; Chemistry;
    ISSN: 1932-7447
    E-ISSN: 1932-7455
    Source: American Chemical Society (via CrossRef)
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  • 6
    Language: English
    In: Chemosphere, January 2014, Vol.95, pp.470-477
    Description: Veterinary antibiotics administered to livestock can be unintentionally released into the environment, for example by the application of manure to soils. The fate of such antibiotics in soils is mostly determined by sorption and degradation processes, including transformation. There is a need to further examine the combined transformation and sorption behavior of these emerging pollutants in soils. Long-term batch sorption experiments with the C-radiolabeled antibiotic sulfadiazine enabled us to simultaneously trace the sorption and transformation dynamics of sulfadiazine. The parent compound and the transformation products were analyzed in the liquid phase and in the extracts from the solid phase after a sequential extraction. We found that of up to six transformation products were formed during degradation and that these products exhibited quite different dynamics in the two soils. Transformation products were formed rapidly and were extractable from the solid phase. We observed identical sets of the transformation products in both phases. The input concentration influenced the course of transformation of the parent substance. We present a detailed analysis including a mathematical description and derive regulatory kinetic endpoints for predicting environmental concentrations.
    Keywords: Sulfadiazine ; Transformation in Soils ; Sorption and Sequestration ; Numerical Studies ; Kinetic Endpoints ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 7
    Language: English
    In: Soil Biology and Biochemistry, 2011, Vol.43(6), pp.1186-1197
    Description: A novel type of planar optodes for simultaneous optical analysis of pH and oxygen dynamics in the rhizosphere is introduced. The combination of the optical, non-invasive measurement of these parameters with sterile sampling of rhizosphere solution across and along growing roots by use of a novel type of rhizobox provides a methodical step forward in the investigation of the physicochemical dynamics of the rhizosphere and its underlying matter fluxes between roots and soil. In this study, this rhizobox was used to investigate the effect of oxygen releasing roots of three species on the amount and distribution of organic acids in reductive, oxygen-deficient soils of different pH (pH 3.9–pH 5.9). Pronounced diurnal variations of oxygen concentration and pH along the roots, particularly along the elongation zone were observed. Long-term records over more than eight weeks revealed considerable spatial and temporal patterns of oxygen over a range of almost 200 μmol O  L and pH dynamics of ±1.4 pH units in the rhizosphere. A strong effect of oxidative acidification due to oxygen release by the plant roots was clearly visible for , whereas the roots of alkalinized the rhizosphere. In contrast, roots of us induced no effects on rhizospheric pH. Only four different organic acids (oxalate, acetate, formate and lactate) were detectable in all soil solutions. Maximal concentration of all organic acids occurred at pH 3.9, whereas the lowest concentration of each organic acid was found at pH 5.9. Hence, considering the pH-dependence of the redox potential, the acid soil provided increased reductive conditions leading to slower anaerobic degradation of organic acids to CO or methane (CH ). The concentration of organic acids decreased by up to 58% within a distance of only 4 mm from the bulk soil to the root surface, i.e. reciprocal to the pronounced O -gradient. The decreasing presence of organic acids toward the oxygen releasing roots is possibly due to a change in the composition of the microbial community from anaerobic to aerobic conditions. The present study highlights the dynamic interplay between O concentration, pH and organic acids as key parameters of the physicochemical environment of the rhizosphere, particularly for wetland plants growing in oxygen-deficient waterlogged soils. ► We used planar optodes for simultaneous analysis of rhizosphere pH and O dynamics. ► Pronounced diurnal changes of O concentration and pH along the roots were measured. ► Records of 8 weeks revealed a dynamic range of 0–200 μmol O  L and ±1.4 pH units. ► Organic acid content decreased up to 58% within 4 mm from the bulk soil to the root.
    Keywords: Planar Optodes ; Non-Invasive Imaging ; Root–Soil Interface ; Minimal-Invasive Sampling ; Microsuction Capillaries ; Waterlogging ; Hypoxia ; Radial Oxygen Loss ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 8
    In: Journal Of Experimental Botany, 2017, Vol. 68(9), pp.2149-2162
    Description: Copper amine oxidase in polyamine metabolism modulates arginine-dependent nitric oxide production by affecting arginase activity in Arabidopsis thaliana . Nitric oxide (NO) is a key signaling molecule in plants, regulating a wide range of physiological processes. However, its origin in plants remains unclear. It can be generated from nitrite through a reductive pathway, notably via the action of the nitrate reductase (NR), and evidence suggests an additional oxidative pathway, involving arginine. From an initial screen of potential Arabidopsis thaliana mutants impaired in NO production, we identified copper amine oxidase 8 (CuAO8). Two cuao8 mutant lines displayed a decreased NO production in seedlings after elicitor treatment and salt stress. The NR-dependent pathway was not responsible for the impaired NO production as no change in NR activity was found in the mutants. However, total arginase activity was strongly increased in cuao8 knockout mutants after salt stress. Moreover, NO production could be restored in the mutants by arginase inhibition or arginine addition. Furthermore, arginine supplementation reversed the root growth phenotype observed in the mutants. These results demonstrate that CuAO8 participates in NO production by influencing arginine availability through the modulation of arginase activity. The influence of CuAO8 on arginine-dependent NO synthesis suggests a new regulatory pathway for NO production in plants.
    Keywords: Arginase ; Arginine ; Copper Amine Oxidase ; Nitric Oxide ; Nitric Oxide Production ; Nitrate Reductase ; Plant.
    ISSN: 0022-0957
    E-ISSN: 1460-2431
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  • 9
    Language: English
    In: Chemosphere, July 2015, Vol.131, pp.34-40
    Description: In this study, we demonstrate a fast and efficient workflow to investigate the transformation mechanism of organic chemicals and evaluate the toxicity of their transformation products (TPs) in laboratory scale. The transformation process of organic chemicals was first simulated by electrochemistry coupled online to mass spectrometry (EC–MS). The simulated reactions were scaled up in a batch EC reactor to receive larger amounts of a reaction mixture. The mixture sample was purified and concentrated by solid phase extraction (SPE) for the further ecotoxicological testing. The combined toxicity of the reaction mixture was evaluated in fish egg test (FET) ( ) compared to the parent compound. The workflow was verified with carbamazepine (CBZ). By using EC–MS seven primary TPs of CBZ were identified; the degradation mechanism was elucidated and confirmed by comparison to literature. The reaction mixture and one primary product (acridine) showed higher ecotoxicity in fish egg assay with 96 h EC values of 1.6 and 1.0 mg L than CBZ with the value of 60.8 mg L . The results highlight the importance of transformation mechanism study and toxicological effect evaluation for organic chemicals brought into the environment since transformation of them may increase the toxicity. The developed process contributes a fast and efficient laboratory method for the risk assessment of organic chemicals and their TPs.
    Keywords: Risk Assessment ; Electrochemistry–Mass Spectrometry ; Ecotoxicity ; Organic Pollutants ; Carbamazepine ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 10
    Language: English
    In: Soil Biology and Biochemistry, February 2013, Vol.57, pp.587-597
    Description: Through their leaf litter and throughfall water, tree species can have a pronounced influence on soil chemistry. However, there is little knowledge of species-specific root effects on greenhouse gas fluxes between forest soils and the atmosphere. By growing saplings of beech ( ) and ash ( ) in monoculture or mixture at defined atmospheric and soil conditions in rhizotrons, we tested four hypotheses related to potential root-induced tree species effects on the uptake of CH and the emission of N O and CO from the soil. This design excluded putative effects of leaf litter mineralisation on trace gas fluxes. Gas fluxes were measured biweekly using the closed chamber technique; the CO derived from root respiration was estimated, and the concentration of organic acids in the rhizosphere solution was analysed. Rhizotrons planted with ash took up significantly more CH and emitted less N O than control rhizotrons without plants. CH and N O fluxes from beech rhizotrons did not differ from the root-free control but were significantly smaller (CH ) or higher (N O) than the fluxes from the ash treatment. While root respiration of ash was higher than of beech, root-induced soil respiration was higher in the rhizosphere of beech roots. The concentration of organic acids tended to be higher in the rhizosphere of beech and also the composition was different from that of ash. We conclude that tree species identity may substantially alter the soil source/sink strength for greenhouse gases through root-related processes. ► Beech and ash saplings affected greenhouse gases in different species-specific ways. ► Ash enhanced the CH uptake and reduced N O emissions through root-related effects. ► Beech roots did not alter CH and N O fluxes compared to root-free soil. ► The calculated root respiration of ash roots was higher than that of beech roots. ► Beech roots appeared to stimulate the rhizosphere respiration more than ash roots.
    Keywords: Fagus Sylvatica ; Fraxinus Excelsior ; Greenhouse Gas Exchange ; Methane Oxidation ; Organic Acids ; Root Growth ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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