Biodegradation of the Antituberculosis Drug Isoniazid in the Aquatic Environment          下载免费PDF全文

Samuel Sasu  Jörg Metzger  Martin Kranert  Klaus Kümmerer 《洁净——土壤、空气、水》2015,43(2):166-172

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On the thick-disc exoplanet host subgiant HD 155358     

Klaus Fuhrmann  Jan Bernkopf † 《Monthly notices of the Royal Astronomical Society》2008,384(4):1563-1566

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On the dynamical origin of the ICM metallicity evolution     

Sofia A. Cora  Luca Tornatore  Paolo Tozzi  Klaus Dolag 《Monthly notices of the Royal Astronomical Society》2008,386(1):96-104

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Numerical simulation of a permittivity probe for measuring the electric properties of planetary regolith and application to the near‐surface region of asteroids and comets     

Klaus SPITZER  Frank SOHL  Martin PANZNER 《Meteoritics & planetary science》2008,43(6):997-1007

Abstract— We present a numerical simulation technique for the retrieval of the electric properties relative permittivity and conductivity of planetary, asteroid, and cometary regolith. Our simulation techniques aim at accompanying hardware development and conducting virtual experiments, e.g., to assess the response of arbitrary heterogeneous conductivity and permittivity distributions or to scrutinize possibilities for spatial reconstruction methods using inverse schemes. In a first step, we have developed a finite element simulation code on the basis of unstructured, adaptive triangular grids for arbitrary two‐dimensional axisymmetric distributions of conductivity and permittivity. The code is able to take into account the spatial geometry of the probe and allows for possible inductive effects. In previous studies, the non‐inductive approach has been used to convert potential and phase data into apparent material properties. By our simulations, we have shown that this approach is valid for the frequency range from 10² Hz to 10⁷ Hz and electric conductivities of 10^?8 S/m that are typical for the near‐surface region of asteroids and comets composed of chondritic materials and/or frozen volatiles such as H₂O and CO₂ ice. We prove the accuracy of our code to be better than 10%, using mixed types of boundary conditions and present a simulated vertical log through a horizontally stratified subsurface layer as a representative example of a heterogeneous distribution of the electrical properties. Resolution studies for the given electrode separation reveal that the material parameters of layers having thicknesses of less than about half the electrode spread are not reconstructible if only apparent quantities are considered. Therefore, spatial distributions of the complex sensitivity are presented having in mind a future data inversion concept that will permit the multi‐dimensional reconstruction of material parameters in heterogeneous environments.  相似文献   

Satellitenbild und Meereiserkundung     

Klaus Strübing 《Ocean Dynamics》1970,23(5):193-213

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Improved prediction of vegetation composition in NW European softwater lakes by combining location,water and sediment chemistry     

Cristina?PulidoEmail author  Kaj?Sand-Jensen  Esther?C.?H.?E.?T.?Lucassen  Jan?G.?M.?Roelofs  Klaus?P.?Brodersen  Ole?Pedersen 《Aquatic Sciences - Research Across Boundaries》2012,74(2):351-360

Isoetids, as indicators of near-pristine softwater lakes, have a high priority in national and international (European Water Directive Framework) assessments of ecological lake quality. Our main goal was to identify the most important environmental factors that influence the composition of plant communities and specifically determine the presence and abundance of the isoetid Lobelia dortmanna in NW European softwater lakes. Geographical position and composition of surface water, porewater, sediment and plant communities were examined in 39 lakes in four regions (The Netherlands, Denmark, West Norway and East Norway) distributed over a 1,200-km long distance. We confirmed that lake location was accompanied by significant changes in environmental variables between NW European lakes. Lake location was the single most important determinant of vegetation composition and it had significant individual contributions independent of the coupling to environmental variables. This influence of location was supported by a significant decline of community similarity with geographical distance between pairs of lakes at regional, inter-regional and international scales. Combining the geographical position with environmental variables for surface water, porewater and sediment significantly improved prediction of vegetation composition. Specifically, the combination of latitude, surface water alkalinity, porewater phosphate and redox potential offered the highest correlation (BIO ENV correlation 0.66) to vegetation composition. This complex analysis can also account for high sediment variability in the littoral zone of individual lakes, by using site-specific physico-chemical sediment factors, and offer better predictions of vegetation composition when lake water chemistry is relatively homogeneous among lakes within regions.  相似文献   

Photodegradation,Photocatalytic, and Aerobic Biodegradation of Sulfisomidine and Identification of Transformation Products by LC–UV‐MS/MS     

Faten Sleman  Waleed M. M. Mahmoud  Rolf Schubert  Klaus Kümmerer 《洁净——土壤、空气、水》2012,40(11):1244-1249

Much attention has recently been devoted to the fate and effects of pharmaceuticals in the water cycle. Removal of antibiotics in effluents by photo‐treatment or biodegradation is a topic currently under discussion. Degradation and removal efficiencies of sulfisomidine (SUI) by photodegradation and aerobic biodegradability were studied. SUI behavior was monitored during photolysis and photocatalysis (catalyst titanium dioxide) using 150‐W medium‐pressure Hg lamp. Also an aerobic bacterial degradation test from the OECD series (closed bottle test (CBT, OECD 301 D)) was performed. The primary elimination of SUI was monitored. Structures of photo‐degradation products were assessed by chromatographic separation on a C18 column with ultraviolet detection at 270 nm and ion trap MS. The results demonstrate that SUI is not readily biodegradable in CBT. Photo catalysis was more is effective than photolysis. SUI underwent photodegradation and several SUI photoproducts were identified. Accordingly, the photodegradation pathway of SUI was postulated. When reaching the aquatic environment, SUI and its photo products can constitute a risk to the environment.  相似文献   

Sensitivity of subglacial Lake Vostok's flow regime on environmental parameters     

Malte Thoma  Christoph Mayer  Klaus Grosfeld 《Earth and Planetary Science Letters》2008,269(1-2):242-247

Subglacial lakes provide unique habitats, but the exact nature of physical and geochemical conditions are still a matter of debate and await direct sampling of water. Due to its isolation from external atmospheric forcing other environmental parameters influence the flow characteristics within the lake. In this study we use an improved treatment of the physical processes at the ice–water boundary interface to identify and quantify the impact of (1) the geothermal heat flux, (2) the heat flux from the lake into the ice, (3) the influence of the salinity of the lake water, and (4) the ice thickness on the size of the freezing area and the freeze/melt rates. We show that the modelled basal mass imbalance (that is the produced melt water minus the re-frozen water) depends on the geothermal heating as well as the heat flux into the ice. The circulation and the temperature distribution within subglacial Lake Vostok are rather stable against variations of geothermal heat flux, heat flux into the ice sheet, salinity of the lake, and small changes of the ice thickness above the lake. However, the flow regime for any subglacial lake with less than 2000 m ice thickness above, will be substantially different from those that experience higher pressures. This is because the buoyancy–temperature relationship reverses at this depth.  相似文献   

Landslides, Ice Quakes, Earthquakes: A Thermodynamic Approach to Surface Instabilities     

Klaus Regenauer-Lieb  David A. Yuen  Florian Fusseis 《Pure and Applied Geophysics》2009,166(10-11):1885-1908

The total rate of rock deformation results from competing deformation processes, including ductile and brittle mechanisms. Particular deformation styles arise from the dominance of certain mechanisms over others at different ambient conditions. Surprisingly, rates of deformation in naturally deformed rocks are found to cluster around two extremes, representing coseismic slip rates or viscous creep rates. Classical rock mechanics is traditionally used to interpret these instabilities. These approaches consider the principle of conservation of energy. We propose to go one step further and introduce a nonlinear far-from-equilibrium thermodynamic approach in which the central and explicit role of entropy controls instabilities. We also show how this quantity might be calculated for complex crustal systems. This approach provides strain-rate partitioning for natural deformation processes occurring at rates in the order of 10^-3 to 10^-9 s^-1. We discuss these processes using examples of landslides and ice quakes or glacial surges. We will then illustrate how the mechanical mechanisms derived from these near-surface processes can be applied to deformation near the base of the seismogenic crust, especially to the phenomenon of slow earthquakes.  相似文献   

193nm ArF准分子激光系统对LA-ICP-MS分析中不同基体的剥蚀行为和剥蚀速率探究   总被引：7，自引：6，他引：1  

吴石头  许春雪  Klaus Simon  肖益林  王亚平 《岩矿测试》2017,36(5):451-459

探究LA-ICP-MS分析中不同基体的剥蚀行为和剥蚀速率,可为激光参数设定、基体匹配选择、数据质量保证等方面提供重要参考。本文研究了193 nm ArF准分子激光系统对人工合成/地质样品玻璃、常见矿物和粉末压片的剥蚀行为,同时探究了激光参数(束斑直径、能量密度和剥蚀频率)对剥蚀速率的影响情况。从剥蚀坑形貌可知,193nm ArF激光对玻璃和绝大多数矿物的剥蚀行为良好,但对石英相对较差,这可能与石英内含有微观包裹体,剥蚀过程中局部受热不均有关。粉末压片的剥蚀行为呈现出不可控,可通过提高粉末压片的压制压力或降低粉末颗粒的粒径来改善剥蚀行为;当剥蚀深度大于1.5倍束斑直径时,剥蚀速率随剥蚀深度的增加而逐渐减小,剥蚀深度最多可达束斑直径的两倍左右(RESOlution M-50型号激光系统,3.0 J/cm2激光能量密度);剥蚀速率随激光能量密度的增加而增大,但基本不受剥蚀频率(2~20 Hz)影响。不同基体具有特征的剥蚀速率,本文报道了43种基体的剥蚀速率参数,总体而言,NIST系列玻璃的剥蚀速率大于地质样品玻璃,碳酸盐矿物和硫化物矿物大于硅酸岩矿物,粉末压片大于玻璃和常见矿物。  相似文献