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  • DSC  (1)
  • Frequency control  (1)
  • N application  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 183 (1998), S. 753-758 
    ISSN: 1432-1351
    Keywords: Key words Tonic depolarization ; EPSP ; Excitatory amino acids ; Locomotion; ; Frequency control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This paper investigates the proposal that the frequency of the swimming central pattern generator in young Xenopus tadpoles is partly determined by the population of glutamatergic premotor interneurons active on each cycle. During fictive swimming spinal neurons also receive cholinergic and electrotonic excitation from motoneurons. As frequency changes during swimming we make two predictions: first, since most motoneurons fire very reliably at all frequencies, the electrotonic and nicotinic drive from motoneurons should remain constant, and second, when swimming frequency decreases, the glutamatergic drive should decrease as the number of active premotor excitatory interneurons decreases. We have tested these predictions by measuring the excitatory synaptic drive to motoneurons as frequency changes during fictive swimming. The components of synaptic drive were revealed by the local microperfusion of strychnine together with different excitatory antagonists. After blocking the nicotinic acetylcholine receptor, the mainly glutmatergic excitatory synaptic drive still changed with frequency. However, when glutamate receptors or all chemical transmission was blocked, excitation did not change with frequency. Our predictions are confirmed, suggesting that premotor excitatory interneurons are a major factor in frequency control in the tadpole central pattern generator and that motoneurons provide a stable background excitation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 771-778 
    ISSN: 1572-8943
    Keywords: burning rate ; DATH ; DSC ; TG ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition characteristics of1,7-diazido-2,4,6-trinitrazaheptane (DATH) and multi-component systems containing DATH were studied by using DSC, TG and DTG techniques. Three –NO2 groups in the DATH molecule break away first from the main chain when DATH is heated up to 200°C. Following this process, the azido groups and the residual molecule decompose rapidly to release a great deal of heat within a short time. In the multi-component systems, DATH undergoes a strong interaction with the binder of the double-base propellant and a weak interaction with RDX. The burning rates of the two propellants were determined by using a Crawford bomb. The results showed that the burning rate rises by about 19–66% when 23.5%DATH is substituted for RDX in a minimum smoke propellant. Meanwhile, the N2 level in the combustion gases is enhanced, which is valuable for a reduction of the signal level of the solid propellant.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5036
    Keywords: glucosinolate content ; N application ; oilseed rape ; S application ; S uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sulphur (S) uptake and distribution in double low (Cobra) and single low (Bienvenu) winter oilseed rape were studied in field experiments at Cockle Park, Northumberland, at a site where the S supply was adequate. Total S uptake at maturity of between 80–100 kg ha-1 was similar in both varieties. Applications of S at a rate of 100 kg ha-1 increased S uptake by 10–15 kg ha-1. while applications of nitrogen (N) at a rate of 300 kg ha-1 increased S uptake by 29–34 kg ha-1. Sulphur distribution in the vegetative tissues varied little between the two varieties but the distribution within the pods differed significantly between the two varieties. In Bienvenu 65.8% of pod S was located in the seeds, while in Cobra 57.4 and 68.8% in the 1988–89 and 1989–90 seasons, respectively, was retained in the pod walls. The high S content of the seeds of Bienvenu was due to their high glucosinolate content, whereas the high content of S in the pod walls of Cobra was associated with the presence of free SO4 2-, which accounted for 70.6 to 89.4% of total S in the pod walls. The percentages of total plant S present in the pods were significantly increased by N applications and slightly decreased by S applications.
    Type of Medium: Electronic Resource
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