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Konstanz, Germany

Sass O.,Institute For Geographie Und Raumforschung | Heel M.,Universitatsstrasse 10 | Hoinkis R.,Institute For Physische Geographie | Wetzel K.-F.,Universitatsstrasse 10
Zeitschrift fur Geomorphologie | Year: 2010

Debris deposition by avalanches was monitored for six years at the Arnspitze south slope in the North-Tyrolean Limestone Alps. The slope investigated was deforested by a severe wildfire event in 1946 and is still largely vegetation-free today. We collected avalanchetransported debris on the snow fields at the base of the slope after ground avalanches in spring. The results show mean sediment yields of 1261 km-2 a-1; the mean erosion rate is 48 mm ka-1 for bedrock or 70 mm ka-1 for soil/debris, respectively. These values are much higher than most previous measurements reported in the literature. Avalanche erosion is extremely variable between the years, ranging from 01 to 215 t per year. The thickness of the snow cover, the timing of the spring melt, debris storage in the preceding years and unknown random factors appear to be responsible for the temporal variations. There are also large spatial differences between the sub-catchments. The highest absolute removal (in tonnes) occurs in the largest catchments; the correlation between catchment size and removal rate (tonnes per unit size) is positive but weak. The investigations indicate that process equilibrium remains disturbed, even after more than 60 years have elapsed. © 2010 Gebr. Borntraeaer Verlaasbuchhandluna. Stuttaart. Germany. Source

Gutsche C.,University of Leipzig | Elmahdy M.M.,University of Leipzig | Elmahdy M.M.,Mansoura University | Kegler K.,University of Leipzig | And 22 more authors.
Journal of Physics Condensed Matter | Year: 2011

Optical tweezers are experimental tools with extraordinary resolution in positioning ( 1nm) a micron-sized colloid and in the measurement of forces ( 50fN) acting on it - without any mechanical contact. This enables one to carry out a multitude of novel experiments in nano-and microfluidics, of which the following will be presented in this review: (i)forces within single pairs of colloids in media of varying concentration and valency of the surrounding ionic solution, (ii) measurements of the electrophoretic mobility of single colloids in different solvents (concentration, valency of the ionic solution and pH), (iii) similar experiments as in (i)with DNA-grafted colloids, (iv) the nonlinear response of single DNA-grafted colloids in shear flow and (v) the drag force on single colloids pulled through a polymer solution. The experiments will be described in detail and their analysis discussed. © 2011 IOP Publishing Ltd. Source

Leinweber K.,Universitatsstrasse 10 | Leinweber K.,University of Konstanz | Muller S.,Universitatsstrasse 10 | G Kroth P.,University of Konstanz
BMC Microbiology | Year: 2016

Background: A current focus of biofilm research is the chemical interaction between microorganisms within the biofilms. Prerequisites for this research are bioassay systems which integrate reliable tools for the planning of experiments with robot-assisted measurements and with rapid data processing. Here, data structures that are both human- and machine readable may be particularly useful. Results: In this report, we present several simplification and robotisation options for an assay of bacteria-induced biofilm formation by the freshwater diatom Achnanthidium minutissimum. We also tested several proof-of-concept robotisation methods for pipetting, as well as for measuring the biofilm absorbance directly in the multi-well plates. Furthermore, we exemplify the implementation of an improved data processing workflow for this assay using the Konstanz Information Miner (KNIME), a free and open source data analysis environment. The workflow integrates experiment planning files and absorbance read-out data, towards their automated processing for analysis. Conclusions: Our workflow lead to a substantial reduction of the measurement and data processing workload, while still reproducing previously obtained results in the A. minutissimum biofilm assay. The methods, scripts and files we designed are described here, offering adaptable options for other medium-throughput biofilm screenings. © 2016 Leinweber et al. Source

Trzaskowski J.,Universitatsstrasse 10 | Quinzler D.,Universitatsstrasse 10 | Bahrle C.,Universitatsstrasse 10 | Mecking S.,Universitatsstrasse 10
Macromolecular Rapid Communications | Year: 2011

Self-metathesis of undecenoic acid with [(PCy 3) 2Cl 2Ru=CHPh] (2), followed by exhaustive hydrogenation yielded pure 1,20-eicosanedioic acid (5) (>99%) free of side-products from isomerization. Polycondensation with eicosane-1,20-diol (6), formed by reduction of the diol, yielded polyester 20,20 (T m=108 °C). By comparison, the known ADMET polymerization of undec-10-enyl undec-10-enoate (7), and subsequent exhaustive polymer- analogous hydrogenation yielded a polyester (poly- 8) with irregular structure of the ester groups in the polymer chain (-O(C=O)-vs. -C(=O)O-) (T m=103 °C). Hydrogenation of secondary dispersions of poly-7 yielded aqueous dispersions of the long-chain aliphatic polyester poly-8. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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