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  • 1
    Digitale Medien
    Digitale Medien
    Simulation of water retention and hydraulic conductivity in soil using a three-dimensional network (2000)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 51 (2000), S. 0 
    Details
    ISSN: 1365-2389
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The conduction of water by soil is fundamental to the way in which soils transport nutrients and pollutants into groundwater. The derivation of relations between water flow and void structure has relied on the implicit assumption that water flows through aligned unconnected cylindrical capillary tubes. We describe a three-dimensionally interconnected model of void structure, called Pore-Cor, which simulates the intrusion of a non-wetting fluid and drainage of a wetting fluid. The model is calibrated by fitting it to the water retention curves of a sandy soil at four depths. The experimental drainage pressures are related to the radii of the entries to the voids by the Laplace equation. The necessities of using this equation, and of employing a simplified void geometry, introduce major approximations into the modelling. Nevertheless, the model is sufficiently precise and versatile to predict trends in other properties usefully. It is illustrated in this work by a close correlation between a predicted and experimental change in saturated hydraulic conductivity with depth, and a realistic unsaturated hydraulic conductivity curve. The saturated and unsaturated hydraulic values are shown to be much more realistic than those predicted by the aligned cylinders model. In addition, the simulations by Pore-Cor indicate that the void network within the sandy soil is acting in a structured rather than a random manner. The Pore-Cor model is currently being used to explain the matrix-flow characteristics of tracers and pollutants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2389.2000.00294.x
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  • 2
    Digitale Medien
    Digitale Medien
    Integrated Biological and Chemical Monitoring: In situ Physiological Responses of Freshwater Crayfish to Fluctuations in Environmental Ammonia Concentrations (1999)
    Springer
    Ecotoxicology 8 (1999), S. 225-237 
    Details
    ISSN: 1573-3017
    Schlagwort(e): Ammonia ; in situ monitoring ; crustacea ; heart rate ; flow injection ; landfill leachate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract A portable, computer-aided physiological monitoring system (CAPMON) has been integrated with an automated, flow injection (FI) based chemical monitor to enable continuous, long-term recording of cardiac activity in selected aquatic organisms, and total ammonia concentration in the surrounding environment. Heart rate of the freshwater crayfish Pacifastacus leniusculus was recorded using non-invasive infrared emitter/detectors to transduce heart beat from 4 animals simultaneously. Data were collected continuously and stored on a laptop computer. The chemical monitor incorporated a gas diffusion unit and a solid state photometric detector. Remote control and data processing were accomplished using an in-house designed microcomputer. The instrumentation was fully evaluated in the laboratory and the field and was shown to be capable of operating unattended for periods of at least 1 week. An exposure-response experiment showed that 4 h exposures to concentrations of ammonia greater than 5 mg l-1 had a significant stimulatory effect on heart rate (ANOVA F=7.6; df=5; P〈0.0005). The feasibility of using the system in situ was demonstrated in a 2 week field trial in which the integrated monitors were successfully deployed at a landfill leachate lagoon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1026400532305
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  • 3
    Digitale Medien
    Digitale Medien
    Automated flow-injection procedures for the determination of hydrolytic enzymes in bioreactor preparations (1992)
    Springer
    Chromatographia 33 (1992), S. 49-52 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Flow-injection analysis ; Hydrolytic enzymes ; Bioreactor preparations ; Spectrophotometric detection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Automated spectrophotometric flow-injection (FI) procedures for the quantitative determination of the hydrolytic enzymes amylase, xylanase, polygalacturonase and protease, acting on macromolecular substrates, are described. The peptides produced by the protease are derivatized with trinitrobenzene sulphonic acid. For the other enzymes, the reducing sugars produced are derivatized with p-aminobenzoylhydrazide (PABH). The FI manifold design allows the choice of any required detetion, range between 0.1 U ml−1 and several hundred U ml−1. Two FI manifold designs are proposed; one optimizes, sample throughput at a high sensitivity level by incorporating several parallel incubation coils, the other minimizes sample volume at a low sensitivity level and facilitates, automation. The instrumentation is largely based on commercial HPLC equipment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276851
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  • 4
    Digitale Medien
    Digitale Medien
    Book reviews (1991)
    Springer
    Chromatographia 32 (1991), S. 483-484 
    Details
    ISSN: 1612-1112
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02327983
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