TY  - GEN
A1  - Elsenbeer, Helmut
A1  - Lack, Andreas
A1  - Cassel, Keith
T1  - Chemical fingerprints of hydrological compartments and flow paths at La Cuenca, western Amazonia
N2  - 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.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 047 
KW  - Chemistry of fresh water
KW  - Runoff and streamflow
KW  - Weathering
Y1  - 1995
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16937
ER  - 
TY  - JOUR
A1  - Wang, Feipeng
A1  - Lack, Alexander
A1  - Xie, Zailai
A1  - Frübing, Peter
A1  - Taubert, Andreas
A1  - Gerhard, Reimund
T1  - Ionic-liquid-induced ferroelectric polarization in poly(vinylidene fluoride) thin films
JF  - Applied physics letters
N2  - 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.
KW  - dielectric polarisation
KW  - ferroelectric thin films
KW  - polymer films
KW  - pyroelectricity
KW  - spin coating
Y1  - 2012
U6  - https://doi.org/10.1063/1.3683526
SN  - 0003-6951
VL  - 100
IS  - 6
PB  - American Institute of Physics
CY  - Melville
ER  -