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Determination of nitrogen reduction levels necessary to reach groundwater quality targets in Slovenia

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Journal of Environmental Sciences 2014年第9期26卷 1806-1817页

作者： Miso Andelov ralf Kunkel Jo?e Uhan Frank Wendland Slovenian Environment Agency Hydrogeological Analysis DivisionVojkova 1bSI-1000 LjubljanaSlovenia Forschungszentrum Jülich (FZJ) Institute of Bio- and Geosciences (IBG)Institute 3: Agrosphere52425 JuelichGermany

Within a collaborative project between Slovenian Environment Agency （ARSO） and Research Center Jfilich （FZJ）, nitrogen reduction levels necessary to reach groundwater quality targets in Slovenia were assessed. For this purpose the hydrological model GROWA- DENUZ was coupled with agricultural N balances and applied consistently to the whole territory of Slovenia in a spatial resolution of 100 x 100 m. GROWA was used to determine the water balance in Slovenia for the hydrologic period 1971-2000. Simultaneously, the displaceable N load in soft was assessed from agricultural Slovenian N surpluses for 2011 and the atmospheric N deposition. Subsequently, the DENUZ model was used to assess the nitrate degradation in soil and, in combination with the percolation water rates from the GROWA model, to determine nitrate concentration in the leachate. The areas showing predicted nitrate concentrations in the leachate above the EU groundwater quality standard of 50 mg NO3/L have been identified as priority areas for implementing nitrogen reduction measures. For these ＂hot spot＂ areas DENUZ was used in a backward mode to quantify the maximal permissible nitrogen surplus levels in agriculture to guarantee a nitrate concentration in percolation water below 50 mg NO3/L. Model results indicate that additional N reduction measures should be implemented in priority areas rather than area-covering. Research work will directly support the implementation of the European Union Water Framework Directive in Slovenia, e.g., by using the maximal permissible nitrogen surplus levels as a framework for the derivation of regionally adapted and hence effective nitrogen reduction measures.

关键词： EU Water Framework DirectiveGroundwater quality targetsNitrate pollutionReactive nitrate transport modeling

CDP-choline to promote remyelination in multiple sclerosis:the need for a clinical trial

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Neural Regeneration Research 2023年第12期18卷 2599-2605页

作者： Viktoria Gudi PawełGrieb ralf ALinker Thomas Skripuletz Department of Neurology Hannover Medical SchoolHannoverGermany Department of Experimental Pharmacology Mossakowski Medical Research InstitutePolish Academy of SciencesWarsawPoland Department of Neurology University Hospital RegensburgRegensburgGermany

Multiple sclerosis is a multifactorial chronic inflammatory disease of the central nervous system that leads to demyelination and neuronal cell death,resulting in functional *** is the natural repair process of demyelination,but it is often incomplete or fails in multiple *** therapies reduce the inflammatory state and prevent clinical ***,therapeutic approaches to increase myelin repair in humans are not yet *** substance cytidine-5′-diphosphocholine,CDP-choline,is ubiquitously present in eukaryotic cells and plays a crucial role in the synthesis of cellular *** properties have been shown in various animal models of diseases of the central nervous *** have already shown that the compound CDPcholine improves myelin regeneration in two animal models of multiple ***,the results from the animal models have not yet been studied in patients with multiple *** this review,we summarise the beneficial effects of CDP-choline on biolipid metabolism and turnover with regard to inflammatory and regenerative *** also explain changes in phospholipid and sphingolipid homeostasis in multiple sclerosis and suggest a possible therapeutic link to CDP-choline.

关键词： astrocytes CDP-choline cuprizone microglia multiple sclerosis oligodendrocytes

Uniform Convergence of Adaptive Multigrid Methods for Elliptic Problems and Maxwell’s Equations

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Numerical Mathematics(Theory,Methods and Applications) 2012年第3期5卷 297-332页

作者： ralf Hiptmair Haijun Wu Weiying Zheng SAM ETH ZürichCH-8092 ZürichSwizerland Department of Mathematics Nanjing UniversityNanjingJiangsu210093China LSEC Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing100190China

We consider the convergence theory of adaptive multigrid methods for secondorder elliptic problems and Maxwell’s *** multigrid algorithm only performs pointwise Gauss-Seidel relaxations on new degrees of freedom and their“immediate”*** the context of lowest order conforming finite element approximations,we present a unified proof for the convergence of adaptive multigrid V-cycle *** theory applies to any hierarchical tetrahedral meshes with uniformly bounded shape-regularity *** convergence rates for both problems are uniform with respect to the number of mesh levels and the number of degrees of *** demonstrate our convergence theory by two numerical experiments.

关键词： MMaxwell’s equations Lagrangian finite elements edge elements adaptive multigrid method successive subspace correction

Second-Kind Boundary Integral Equations for Scattering at Composite Partly Impenetrable Objects

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Communications in Computational Physics 2018年第1期23卷 264-295页

作者： Xavier Claeys ralf Hiptmair Elke Spindler Sorbonne Universites UPMC Univ Paris 06CNRSINRIAUMR 7598Laboratoire Jacques-Louis Lionsequipe AlpinesF-75005ParisFrance Seminar for Applied Mathematics Swiss Federal Institute of TechnologyCH-8092 ZurichSwitzerland

We consider acoustic scattering of time-harmonic waves at objects composed of several homogeneous *** of those may be impenetrable,giving rise to Dirichlet boundary conditions on their *** start from the recent secondkind boundary integral approach of[***,and ***,and ***.A second-kind Galerkin boundary element method for scattering at composite *** Numerical Mathematics,55(1):33-57,2015]for pure transmission problems and extend it to settings with essential boundary *** on so-called global multipotentials,we derive variational second-kind boundary integral equations posed in L^(2)(S),where S denotes the union of material *** suppress spurious resonances,we introduce a combined-field version(CFIE)of our new *** numerical tests highlight the low andmesh-independent condition numbers of Galerkin matrices obtained with discontinuous piecewise polynomial boundary element *** also confirm competitive accuracy of the numerical solution in comparison with the widely used first-kind single-trace approach.

关键词： Acoustic scattering second-kind boundary integral equations Galerkin boundary element methods

Critical evaluation of two models of flow cytometers for the assessment of sperm DNA fragmentation:an appeal for performance verification

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Asian Journal of Andrology 2019年第5期21卷 438-444页

作者： Rakesh Sharma Sajal Gupta ralf Henkel Ashok Agarwal American Center for Reproductive Medicine Cleveland ClinicClevelandOH 44195USA Department of Medical Bioscience University of the Western CapeBellville 7535South Africa

Lack of standardized,reproducible protocols and referencO values is among the challenges faced when using new or upgraded versions of instruments in reproductive laboratories and flow *** deoxynucleotidyl transferase dUTP nick end labeling(TUNEL)assay combined with flow cytometry routinely used for diagnostic measurement of sperm DNA fragmentation(SDF)is a unique *** change in the setting of the standard instrument,including upgrades of hardware or software,can lead to different results and may affect clinicians'decision for ***,we compared TUNEL results of SDF obtained from a standard(C6)flow cytometer with a newer version of the same instrument(C6 Plus)and examined the cutoff,sensitivity,and specificity without calibration(adjustment)and after *** sperm preparation and matched acquisition settings were used to examine the performance of two flow *** strength of agreement of the results between the two observers was also *** adjustment of the settings,overall concordance became high and the two cytometers showed 100%positive and negative predictive value with 100%area under the *** overall correlation coefficient observed between C6 and C6 Plus was highly significant(P99%.The in terobserver agreeme nt on C6 flow cytometer for the two observers was 0.801±0.062 and 0.746±0.044 for C6 *** demonstrated a strong agreement between the samples tested on the two flow cytometers after calibration and established the robustness of both instruments.

关键词： DNA fragmentation flow cytometer oxidative stress sperm TUNEL assay

Determination of polyfluoroalkyl compounds in water and suspended particulate matter in the river Elbe and North Sea,Germany

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Frontiers of Environmental Science & Engineering 2009年第2期3卷 152-170页

作者： Lutz AHRENS Merle PLASSMANN Zhiyong XIE ralf EBINGHAUS Institute for Coastal Research GKSS Research Centre Geesthacht GmbHD-21502 GeesthachtGermany Institute for Ecology and Environmental Chemistry Leuphana University of LüneburgD-21335 LüneburgGermany Department of Applied Environmental Science(ITM) Stockholm UniversitySE-10691 StockholmSweden

The distribution of polyfluoroalkyl compounds(PFCs)in the dissolved and particulate phase and their discharge from the river Elbe into the North Sea were *** PFCs quantified included C_(4)-C_(8) perfluorinated sulfonates(PFSAs),6∶2 fluorotelomer sulfonate(6∶2 FTS),C_(6) and C_(8) perfluorinated sulfinates(PFSiAs),C_(4)-C_(12) perfluorinated carboxylic acids(PFCAs),perfluoro-3,7-dimethyl-octanoic acid(3,7m_(2)-PFOA),perfluorooctane sulfonamide(FOSA),and n-ethyl perfluroctane sulfonamidoethanol(EtFOSE).PFCs were mostly distributed in the dissolved phase,where perfluorooctanoic acid(PFOA)dominated with 2.9–12.5 ng/*** the suspended particulate matter FOSA and perfluorooctane sulfonate(PFOS)showed the highest concentrations(4.0 ng/L and 2.3 ng/L,respectively).The total flux ofΣPFCs from the river Elbe was estimated to be 802 kg/year for the dissolved phase and 152 kg/year for the particulate *** indicates that the river Elbe acts as a source of PFCs into the North ***,the concentrations of perfluorobutane sulfonate(PFBS)and perfluorobutanoic acid(PFBA)in the North Sea were higher than that in the river Elbe,thus an alternative source must exist for these compounds.

关键词： polyfluoroalkyl compounds(PFCs) perfluorooctane sulfonate(PFOS) perfluorooctanoic acid(PFOA) surface water water-particulate partitioning

Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

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Frontiers of Environmental Science & Engineering 2009年第2期3卷 226-235页

作者： Fangyue LI Joachim BEHRENDT Knut WICHMANN ralf OTTERPOHL Institute of Water Resources and Water Supply Hamburg University of TechnologySchwarzenbergstr.95 ED-21073 HamburgGermany Department of Wastewater Management Hamburg University of TechnologyEissendorfer Strasse 42D-21073 HamburgGermany

In this study,a mathematical model was established to predict the formation of the soluble microbial product(SMP)in a submerged membrane *** developed model was calibrated under the reference *** results were in good agreement with the measured results under the reference *** calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters:hydraulic retention time(HRT),dissolved oxygen concentration,and sludge retention time(SRT).Simulation results revealed that the SMP dominated the soluble organic substances in the *** scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality;dissolved oxygen concentration in the reactor can be kept at 2–3 mg/L to maintain the effluent quality,reduce the content of SMP,and minimize operating costs;the optimal SRT can be controlled to 10–15 d to achieve complete nitrification process,less membrane fouling potential,and acceptable organic removal efficiency.

关键词： hybrid activated sludge model(ASM) membrane bioreactor(MBR) soluble microbial product(SMP)

Equilibrium Segregation to Free Surface:Kinet ics and Experiment

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Chinese Physics Letters 1999年第5期16卷 364-366页

作者： CAO Ze-xian ralf Mueller WANG En-ge NIE Yu-xin State Key Laboratory for Surface Physics Institute of PhysicsChinese Academy of SciencesBeijing 100080 Department of Physics University Kaiserslautern67653 KaiserslauternGermany

Fick's first law is modified with an additional term df(x)/dx to describe the segregation phenomenon,f(x)is a local,analytical function related to the depth profile at *** thus can be determined experimentally by depth profiling *** starting in an initially homogeneous solid is described by an inhomogeneous diffusion equation on the half-infinite *** with and without formation of overlayer suggests different boundary *** solution for the Ansatz f(x)=as exp(-x/d_(s))is in perfect agreement with experimental results on sulphur segregation to the surface of *** from the detailed kinetics,activation energy can be inferred from the surface concentration evolution under different *** sulphur segregation in titanium,E_(act)=718 meV/atom.

关键词： technique. titanium sulphur

Combination of cold drawing and cryogenic turning for modifying surface morphology of metastable austenitic AISI 347 steel

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Journal of Iron and Steel Research International 2019年第11期26卷 1188-1198页

作者： Hendrik Hotz Benjamin Kirsch Steven Becker ralf Miiller Jan CAurich Institute for Manufacturing Technology and Production Systems University of Kaiserslautern67663 KaiserslauternGermany Institute of Applied Mechanics University of Kaiserslautern67663 KaiserslauternGermany

The application of components often depends to a large extent on the properties of the surface layer.A novel process chain for the production of components with a hardened surface layer from metastable austenitic steel was *** investigated metastable austenitic AISI 347 steel was cold-drawn in solution annealed condition at cryogenic temperatures for pre-hardening,followed by post-hardening via cryogenic *** increase in hardness in both processes was due to strain hardening and deformation-induced phase transformation from y-austenite to^-*** turning experiments were carried out with solution annealed AISI 347 steel as well as with solution annealed and subsequently cold-drawn AISI 347 *** thermomechanical load of the workpiece surface layer during the turning process as well as the resulting surface morphology was *** forces and temperatures were higher in turning the cold-drawn AISI 347 steel than turning the solution annealed AISI 347 *** cryogenic turning of the solution annealed material,deformation-induced phase transformation and a significant increase in hardness were detected in the near-surface *** contrast,no additional phase transformation was observed after cryogenic turning of the cold-drawn AISI 347 *** maximum hardness in the surface layer was similar,whereas the hardness in the core of the cold-drawn AISI 347 steel was higher compared to that in the solution annealed AISI 347 steel.

关键词： Surface layer hardening Cryogenic turning Cold drawing Metastable austenitic steel Deformation-induced phase transformation