@misc{ElsenbeerLackCassel1995, author = {Elsenbeer, Helmut and Lack, Andreas and Cassel, Keith}, title = {Chemical fingerprints of hydrological compartments and flow paths at La Cuenca, western Amazonia}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16937}, year = {1995}, abstract = {A forested first-order catchment in western Amazonia was monitored for 2 years to determine the chemical fingerprints of precipitation, throughfall, overland flow, pipe flow, soil water, groundwater, and streamflow. We used five tracers (hydrogen, calcium, magnesium, potassium, and silica) to distinguish "fast" flow paths mainly influenced by the biological subsystem from "slow" flow paths in the geochemical subsystem. The former comprise throughfall, overland flow, and pipe flow and are characterized by a high potassium/silica ratio; the latter are represented by soil water and groundwater, which have a low potassium/silica ratio. Soil water and groundwater differ with respect to calcium and magnesium. The groundwater-controlled streamflow chemistry is strongly modified by contributions from fast flow paths during precipitation events. The high potassium/silica ratio of these flow paths suggests that the storm flow response at La Cuenca is dominated by event water.}, language = {en} } @article{WangLackXieetal.2012, author = {Wang, Feipeng and Lack, Alexander and Xie, Zailai and Fr{\"u}bing, Peter and Taubert, Andreas and Gerhard, Reimund}, title = {Ionic-liquid-induced ferroelectric polarization in poly(vinylidene fluoride) thin films}, series = {Applied physics letters}, volume = {100}, journal = {Applied physics letters}, number = {6}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0003-6951}, doi = {10.1063/1.3683526}, pages = {4}, year = {2012}, abstract = {Thin films of ferroelectric beta-phase poly(vinylidene fluoride) (PVDF) were spin-coated from a solution that contained small amounts of the ionic liquid (IL) 1-ethyl-3-methylimidazolium nitrate. A remanent polarization of 60 mC/m(2) and a quasi-static pyroelectric coefficient of 19 mu C/m(2)K at 30 degrees C were observed in the films. It is suggested that the IL promotes the formation of the beta phase through dipolar interactions between PVDF chain-molecules and the IL. The dipolar interactions are identified as Coulomb attraction between hydrogen atoms in PVDF chains and anions in IL. The strong crystallinity increase is probably caused by the same dipolar interaction as well.}, language = {en} }