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  • 1
    Electronic Resource
    Electronic Resource
    Relaxation of Polar Order in Poled Polymer Systems: A Comparison between an Isothermal and a Thermally Stimulated Experiment (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 2882-2885 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00112a038
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Quantitative analysis of earthworm burrow systems with respect to biological soil-structure regeneration after soil compaction (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 219-229 
    Details
    ISSN: 1432-0789
    Keywords: Key words Earthworms ; Soil compaction ; Burrow systems ; X-ray computed tomography ; Biological soil-structure regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  On arable land, tilled with conventional tillage (CT) and conservation tillage (CS) respectively, plots were compacted by wheeling them 6 times with a 5 Mg wheel load in spring 1995. Immediately after compaction, undisturbed soil monoliths were excavated from the compacted and uncompacted plots. The monoliths were defaunated and inoculated with either Lumbricus terrestris or Aporrectodea caliginosa. One monolith from each plot remained uninoculated as a control. After 6 months the monoliths were defaunated again and then scanned with X-ray helical computed tomography. The data were transformed, the void systems inside the monoliths were reconstructed and visualised, and the parameters total void length, total void volume, tortuosity and continuity were quantified. The parameters' values were generally lower in the controls than in the inoculated monoliths. Differences in burrow construction could be explained by the different life strategies of the two earthworm species. Changes in burrow morphology due to tillage system and soil compaction were minor. Only the continuity of the burrow systems clearly changed: decreasing for L. terrestris and increasing for A. caliginosa. This can be explained by a change in the earthworms' burrowing activity to minimise energy expenditure in compacted soil. By extrapolating field data, we concluded that earthworms have great potential for biologically regenerating the soil structure after a single compaction event. Due to higher earthworm abundances in soil managed by CS the regeneration of the soil structure is assumed to be better in these plots than those tilled by CT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050486
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  • 3
    Electronic Resource
    Electronic Resource
    Impact of Collembola and Enchytraeidae on soil surface roughness and properties (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 396-400 
    Details
    ISSN: 1432-0789
    Keywords: Key words Collembola ; Enchytraeidae ; Casts ; Soil ; surface roughness ; Soil tillage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of the study was to quantify the alteration of soil surface roughness caused by the casting activity of mesofauna. Undisturbed soil monoliths with a surface area of 5000mm2 were taken from the upper 4cm of the Ap-horizon in agricultural land. Two tillage systems were studied: conventional tillage (CT) and conservation tillage (CS). The sampling plots were mechanically compacted by wheeling with graded loads. Sampling occurred in spring after compaction and before seeding. The soil monoliths were defaunated before inoculating one half of the monoliths with 150 individuals of Collembola (Folsomia candida) and the other half with 100 individuals of Enchytraeidae (90% Enchytraeus minutus and 10% E. lacteus). Soil surface roughness was measured using a noncontact laser scanner: before inoculation and 6 months later. Photographs show the soil surface covered with casts. Results from laser scanning show that in most cases the surface roughness increased due to mesofaunal activity. However, roughness decreased when cracks were filled with casts. The casting activity and surface roughness changes are highest in uncompacted soil. A high degree of soil compaction significantly reduced the activity at the surface. In most cases the soil surface is more altered in CT than in CS. When the content of carbon and nitrogen were determined, both elements were accumulated in the casts but more by Collembola than Enchytraeidae. The results are discussed in the context of the hemiedaphic (F. candida) and the euedaphic (Enchytraeus spp.) mode of living.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050331
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  • 4
    Electronic Resource
    Electronic Resource
    Axial and radial pressure exerted by earthworms of different ecological groups (1999)
    Springer
    Biology and fertility of soils 29 (1999), S. 262-269 
    Details
    ISSN: 1432-0789
    Keywords: Keywords Axial pressure ; Earthworms ; Ecological groups ; Radial pressure ; Burrowing activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The aim of this study was to measure the pressures exerted by earthworms during burrowing. For this purpose we developed two methods with which to quantify the axial and radial pressure. The data were recorded with an electronic balance that was connected to a PC. Artificial earthworm burrows were used to standardize the measurements. Plexiglas tubes with diameters ranging from 2 to 6.3 mm which corresponded to the diameter of the earthworms were used. A pin was placed inside the tubes, on which the earthworms exerted a pressure by peristaltic locomotion. Only the maximum values of the pressure measurement were taken into account for evaluation, and the arithmetic mean was calculated. The measurements were conducted with Aporrectodea longa, Lumbricus terrestris, Aporrectodea caliginosa, Octolasion cyaneum, Allolobophora chlorotica, Aporrectodea rosea, Lumbricus rubellus and Dendrobaena octaedra. The species examined were classified into ecological groups. The mean axial pressures exerted by each group were in the order: epigeic (14–25 kPa), endogeic (27–39 kPa) and anecic (46–65 kPa). For the mean radial pressure the order was: epigeic (39–63 kPa), anecic (72–93 kPa) and endogeic (59–195 kPa). It was apparent from the results that radial pressure is the most important pressure with respect to the burrowing activity of earthworms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050551
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of phenolic compounds in waste water by solid-phase micro extraction (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 326-332 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The solid-phase micro extraction technique (SPME) using a polyacrylate coated fibre has been examined with the aim to determine phenolic components in strong contaminated waste water. Considering the high contents and the great variety of accompanying organic material, the feasibility of SPME-GC-MS analysis has been tested. In this connection the influence of matrix components on the SPME results are discussed. EPA-604 phenols and some other phenolic components have been sampled by a polar fibre under standard conditions and in original waste water. The effects of defined concentrations of humic acids and surfactants on the recovery of phenols have been studied. The influence of other organics, e.g. hexachlorocyclohexane isomers, on the recoveries of phenols are discussed. Finally, a comparison between results of a liquid-liquid extraction and SPME describes the performance of SPME regarding the phenol analysis of strong-loaded water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050162
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Colourless, transparent conductive polymer films with ultrathin networks of organic crystals (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 6 (1996), S. 330-334 
    Details
    ISSN: 1057-9257
    Keywords: conductive composites ; organic metals ; BEDO-TTF ; nanocrystals ; polymer composites ; optical properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The possibilities of increasing the transparency of conductive organic polymeric composites obtained by growing crystalline conductive networks in situ are discussed and new methods of preparation of practically colourless conductive polymer films are presented. We show that in most cases the colour which appears during the preparation of a conducting composite by reticulate doping is not directly related to the conducting network, which usually consist of relatively well-formed microcrystals, but results instead from the additive molecules present in the polymer matrix as less organised aggregates or a molecularly dispersed phase. By an appropriate choice of preparation conditions or electrochemically one can get rid of the strongly absorbing part of the complex so that the absorption in the visible range can be substantially reduced without losing conductivity and without deterioration of the conductive network.These phenomena are demonstrated on polycarbonate with fine networks of BEDO-TTF iodine and bromine salts obtained by casting or spin coating in order to obtain thin homogeneous films, e.g. to prepare electrodes for electro-optical investigations. Transparent, colourless conductive films 20-2 μm thick (surface resistivity of the order of 103-104 Ω/□) have been obtained and the structure of the conductive networks in these materials, their optical properties in the visible and near-infrared range as well as their electrical properties are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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