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  • Articles: DFG German National Licenses  (4)
  • Polymer and Materials Science  (2)
  • Biological soil-structure regeneration  (1)
  • Key words Collembola  (1)
  • 1
    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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    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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    Paper (German National Licenses)
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  • 3
    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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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Matrixmorphologie von phenolharzgebundenen Cellulosepapier-Schichtpreßstoffen (1990)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 273-279 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: By transmission electron microscopy, globular structures were observed on the fracture surface of the phenolic resin matrix. From water diffusion experiments the existence of a layer between the globules with a lower network density can be deduced. When the resin is modified by NBR or by tung oil combined with tricresyl phosphate, two separated phases are indicated by dynamic mechanical analysis, by thermally stimulated depolarization measurements, and by TEM.
    Notes: Auf Matrixbruchflächen werden mittels Transmissionselektronenmikroskopie globulare Strukturen beobachtet. Aus Untersuchungen zur Wasserdiffusion kann auf eine Zwischenschicht mit geringerer Vernetzungsdichte geschlossen werden. Ist die Harzmatrix mit NBR-Kautschuk oder mit Holzöl in Kombination mit Tricresylphosphat modifiziert, so weisen die dynamisch-mechanische Analyse, Messungen der thermisch stimulierten Depolarisation und TEM-Untersuchungen auf zwei separierte Phasen hin.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1990.010410503
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    Paper (German National Licenses)
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