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  • Articles: DFG German National Licenses  (4)
  • 2000-2004  (4)
  • DOC-mobilization  (1)
  • Growth-response description  (1)
  • PACS. 75.50.Xx Molecular magnets – 75.10.Jm Quantized spin models – 75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)  (1)
  • Pseudarthrose  (1)
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  • Articles: DFG German National Licenses  (4)
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  • 2000-2004  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 32 (2000), S. 73-81 
    ISSN: 1432-0789
    Keywords: Key words Active microbial biomass ; Substrate-induced respiration ; Sustaining microbial biomass ; Growth-response description
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  A model describing the respiration curves of glucose-amended soils was applied to the characterization of microbial biomass. Both lag and exponential growth phases were simulated. Fitted parameters were used for the determination of the growing and sustaining fractions of the microbial biomass as well as its specific growth rate (μ max). These microbial biomass characteristics were measured periodically in a loamy silt and a sandy loam soil incubated under laboratory conditions. Less than 1% of the biomass oxidizing glucose was able to grow immediately due to the chronic starvation of the microbial populations in situ. Glucose applied at a rate of 0.5 mg C g–1 increased that portion to 4–10%. Both soils showed similar dynamics with a peak in the growing biomass at day 3 after initial glucose amendment, while the total (sustaining plus growing) biomass was maximum at day 7. The microorganisms in the loamy silt soil showed a larger growth potential, with the growing biomass increasing 16-fold after glucose application compared to a sevenfold increase in the sandy loam soil. The results gained by the applied kinetic approach were compared to those obtained by the substrate-induced respiration (SIR) technique for soil microbial biomass estimation, and with results from a simple exponential model used to describe the growth response. SIR proved to be only suitable for soils that contain a sustaining microbial biomass and no growing microbial biomass. The exponential model was unsuitable for situations where a growing microbial biomass was associated with a sustaining biomass. The kinetic model tested in this study (Panikov and Sizova 1996) proved to describe all situations in a meaningful, quantitative and statistically reliable way.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 71 (2000), S. 1098-1106 
    ISSN: 1433-0385
    Keywords: Schlüsselwörter: Femur ; Pseudarthrose ; Revisionschirurgie ; Versagen primärer Osteosynthesen ; Keywords: Femur ; Pseudarthrosis ; Fracture care ; Failure of primary implants ; Revision procedures.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Between 1981 and 1994 at the Bergmannsheil Ruhr University Hospital in Bochum, Germany, we treated 145 patients with femoral diaphyseal nonunions following initial operative treatment. Of these patients, 138 received this initial operative treatment at an outside institution. The primary reconstructions for the fractures utilized plates in 112 cases, reamed nails in 24 cases and external fixators in 9 cases. The average age of the patients was 35 years and the mean time from the initial operative treatment was 2 years. Twenty-seven patients (19 %) presented with a hypertrophic nonunion and 118 (81 %) with an atrophic nonunion. There was a significant correlation between primary “classic” plating and development of an atrophic nonunion (χ 2-test: P 〈 0.01). We observed 34 wound infections (23 %) with no significant correlation to the type of primary osteosynthesis. We determined that 73 of the pseudarthroses were due to improper osteosynthesis techniques. Of these cases, 41 % involved the use of plates, 83 % involved the use of reamed nails, and 78 % involved the use of external fixators. Fracture location near the diaphyseal-metaphyseal junctions was common in this problematic group. Ninety-two percent of all plates led to atrophic nonunions. There were 21 open fractures and of these 90 % (n = 19) developed an atrophic pseudarthrosis and 29 % (n = 6) developed a wound infection. Fifty-seven (39 %) of all patients had additional injuries, but we found that did not increase the risk of disturbed bone healing. Our revision operations focused on the elimination of wound infections, refreshment of bone healing, and improvement in fragment stability. Only 28 % of all “classic” plates and 11 % of all external fixators were changed to an intramedullary implant at the time of the first revision surgery. Hypertrophic nonunions required a mean of 1.3 revision operations to achieve bone healing whereas a mean of 2 revision operations were necessary to fuse atrophic bone ends (P 〈 0.05). In cases of diaphyseal pseudarthrosis healing time was not affected by the type of osteosynthesis used for primary reconstructions. Since lack of fracture healing can often already be observed directly from postoperative X-rays, we recommend that revision procedures be performed early. The prolonged length of time to care for femoral nonunions underlines the importance of appropriate primary fracture treatment. That takes into consideration both the biomechanical and the biological aspects of bone healing.
    Notes: Zusammenfassung. Zwischen 1981 und 1994 wurden an der Chirurgischen Universitätsklinik Bergmannsheil 145 Patienten mit diaphysären Femurpseudarthrosen behandelt. Die Primärosteosynthesen setzten sich aus 112 Plattenanlagen (77 %), 24 Marknagelungen (17 %) und 9 Fixateur externen (6 %) zusammen. Das Durchschnittsalter betrug 35 Jahre, die mittlere Behandlungsdauer 2 Jahre. 27 Patienten (19 %) hatten eine hypertrophe und 118 (81 %) eine atrophe Pseudarthrosenform. Zwischen den primären „klassischen“ Plattenosteosynthesen und der Häufigkeit areaktiver Heilungsstörungen bestand ein hoch signifikanter Zusammenhang (χ 2-Test: p 〈 0,01). 34 Wundinfektionen (23 %) nach dem Ersteingriff verteilten sich prozentual gleichmäßig auf alle Implantate. Als Ursache der Pseudarthrosenentwicklung sahen wir biomechanisch unzureichende Primärosteosynthesen bei insgesamt 73 Patienten (50 %), 41 % der Platten, 83 % der Marknägel und 78 % der Fixateure. Die metaphysennahen Schaftfrakturen waren hierdurch signifikant häufiger betroffen. Der Anteil an areaktiven Pseudarthrosen nach vorangegangener Plattenosteosynthese betrug 92 % (n = 103). Von 21 offenen Schaftfrakturen entwickelten 90 % (n = 19) eine avitale Pseudarthrose und insgesamt 29 % (n = 6) einen Wundinfekt. Zusätzliche Verletzungen lagen nur bei 39 % (n = 57) der Behandelten vor und hatten für die Pseudarthrosenentwicklung keine Bedeutung. Die Revisionseingriffe zielten auf eine Infektbehandlung, Revitalisation und Stabilitätsverbesserung ab. Der Verfahrenswechsel zum Marknagel erfolgte während der Erstrevision nur bei 28 % der Platten und 11 % der Fixateure. Während hypertrophe Pseudarthrosen schon nach durchschnittlich 1,3 Revisionen ausheilten, waren bei den areaktiven Störungen im Mittel 2 Wiederholungseingriffe notwendig (p 〈 0,05). Die Heilungsdauer von Pseudarthrosen nach Plattenanlage unterschied sich nicht wesentlich von der nach primärer, gebohrter Marknagelung. Da die sich abzeichnende Knochenheilungsstörung häufig schon auf den unmittelbaren postoperativen Röntgenbildern antizipiert werden kann, empfehlen wir notwendige Folgeeingriffe deutlich frühzeitiger durchzuführen. Der lange Behandlungsverlauf unterstreicht die Bedeutung adäquater Frakturversorgungen unter Berücksichtigung biologischer Heilungsvorgänge.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5036
    Keywords: land use ; DOC-mobilization ; soil organic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The conversion of natural forests into cultivated lands causes changes of the carbon cycle, which are of particular importance for fragile landscapes. We examined the mobilization of organic carbon in undisturbed soil monoliths of a deciduous forest, a pine plantation, and a pasture under constant temperature (20°C) and moisture via a leaching experiment. Soil percolation was performed with synthetic rainfall solution (pH 5) for a period of 20 weeks. The leachates of the first 12 weeks were analyzed for the pH, DOC content, light absorbance at 260 and 330 nm. At the end of the experiment soil pH, total carbon, C:N ratio, content of fractions of humic substances were examined. After 20 weeks of the leaching experiment the decrease of soil total Corg reached 29, 23, and 50% in soil monoliths of deciduous forest, pasture, and coniferous forest, respectively. The amounts of DOC removed constituted 6.4, 3.8, and 6.2% of initial soil Corg, respectively. Cumulative values of DOC production decreased in the sequence coniferous forest 〉 deciduous forest 〉 pasture. UV-Vis absorptivities of DOC were similar in both forests and differed from those in pasture. UV-Vis characteristics showed that DOC composition changed during the experiment. The intensive soil percolation caused alterations of the properties of soil organic matter, in particular a change of fraction composition of humic substances occurred.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 24 (2001), S. 475-481 
    ISSN: 1434-6036
    Keywords: PACS. 75.50.Xx Molecular magnets – 75.10.Jm Quantized spin models – 75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: For many spin systems with constant isotropic antiferromagnetic next-neighbour Heisenberg coupling the minimal energies E min(S) form a rotational band, i.e. depend approximately quadratically on the total spin quantum number S, a property which is also known as Landé interval rule. However, we find that for certain coupling topologies, including recently synthesised icosidodecahedral structures this rule is violated for high total spins. Instead the minimal energies are a linear function of total spin. This anomaly results in a corresponding jump of the magnetisation curve which otherwise would be a regular staircase.
    Type of Medium: Electronic Resource
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