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  • 1
    Electronic Resource
    Electronic Resource
    Assessing the roles of glutamatergic and cholinergic synaptic drive in the control of fictive swimming frequency in young Xenopus tadpoles (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 753-758 
    Details
    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
    URL: http://dx.doi.org/10.1007/s003590050298
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal Decomposition Characteristics of 1,7-Diazido-2,4,6-trinitrazaheptane and its Application in Propellants (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 771-778 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1010136928207
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  • 3
    Electronic Resource
    Electronic Resource
    Penetration and adhesion behaviour of boron nitride by liquid aluminium (1992)
    Springer
    Journal of materials science 11 (1992), S. 199-201 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00741420
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  • 4
    Electronic Resource
    Electronic Resource
    Crystallization of Fe-B amorphous alloy powders produced by chemical reduction (1990)
    Springer
    Hyperfine interactions 55 (1990), S. 981-985 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The crystallization behaviour of the Fe−B amorphous alloy powders prepared by the chemical reduction method has been investigated by Mössbauer spectroscopy. In comparison to amorphous ribbons prepared by melt-spinning, a different crystallization behaviour has been observed. After annealing the amorphous samples entirely crystallized into three crystalline phases: α-Fe, Fe3B, and Fe2B. In the case of Fe80B20 amorphous alloy ribbons produced by melt-spinning technique eutectic crystallization is commonly observed and results in the crystalline phases: α-Fe and Fe3B. This kind of crystallization was not observed in the chemically prepared samples. The metastable tetragonal Fe3B phase transformed completely into α-Fe and Fe2B after annealing at 973 K for one hour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397110
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  • 5
    Electronic Resource
    Electronic Resource
    Extractable sulphate and organic sulphur in soils and their availability to plants (1994)
    Springer
    Plant and soil 164 (1994), S. 243-250 
    Details
    ISSN: 1573-5036
    Keywords: organic sulphur ; soil testing ; sulphate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ten soils collected from the major arable areas in Britain were used to assess the availability of soil sulphur (S) to spring wheat in a pot experiment. Soils were extracted with various reagents and the extractable inorganic SO4-S and total soluble S(SO4-S plus a fraction of organic S) were determined using ion chromatography (IC) or inductively-coupled plasma atomic emission spectrometry (ICP-AES), respectively. Water, 0.016 M KH2PO4, 0.01 M CaCl2 and 0.01 M Ca(H2PO4)2 extracted similar amounts of SO4-S, as measured by IC, which were consistently smaller than the total extractable S as measured by ICP-AES. The amounts of organic S extracted varied widely between different extractants, with 0.5 M NaHCO3 (pH 8.5) giving the largest amounts and 0.01 M CaCl2 the least. Organic S accounted for approximately 30–60% of total S extracted with 0.016 M KH2PO4 and the organic C:S ratios in this extract varied typically between 50 and 70. The concentrations of this S fraction decreased in all soils without added S after two months growth of spring wheat, indicating a release of organic S through mineralisation. All methods tested except 0.5 M NaHCO3-ICP-AES produced satisfactory results in the regression with plant dry matter response and S uptake in the pot experiment. In general, 0.016 M KH2PO4 appeared to be the best extractant and this extraction followed by ICP-AES determination was considered to be a good method to standardise on.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010076
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  • 6
    Electronic Resource
    Electronic Resource
    Responses of two wheat varieties to sulphur addition and diagnosis of sulphur deficiency (1996)
    Springer
    Plant and soil 181 (1996), S. 317-327 
    Details
    ISSN: 1573-5036
    Keywords: diagnosis ; glutathione ; N:S ratio ; sulphur ; sulphate ; wheat variety
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sulphur deficiency has become increasingly widespread in wheat in the U.K. Growth, nutrient content and biochemical responses to S and N supply of a breadmaking wheat variety (Hereward) and a non-breadmaking variety (Riband) were investigated in a pot experiment. Shoot dry matter (DM) at stem extension (Zadok's GS 37) and at maturity was increased markedly by S. Grain production of the Riband variety was more susceptible to the imbalance of N to S than the Hereward variety. At GS 37, the concentrations of total S and sulphate-S of shoots, chlorophyll meter readings and the concentrations of glutathione of the uppermost fully expanded leaves were increased significantly by increasing S supply, whereas the concentrations of nitrate and amides were decreased by S. The greatest relative changes in response to S supply were those of the glutathione and asparagine concentrations. Riband also showed greater response to S than Hereward. Critical values of various diagnostic indices at GS 37 were derived from the relationships between DM yield and different indices. The two varieties showed similar diagnostic curves except that for the ratio of total N to total S (N:S) in shoots. Either total S or sulphate-S can be used alone as a good indicator of deficiency, and with values of 1500 and 190 mg kg-1 DM in shoots for the two indices respectively. There was also a well defined relationship between DM yield and the glutathione concentration, with a critical value of 240 nmol g-1 FW. There were no advantages of using % of total S as sulphate-S. Shoot N:S ratio was found to be less accurate in predicting S deficiency than total S or sulphate-S. For prognostic purposes, a much higher S status at GS 37 was required to ensure no losses of DM yield due to S deficiency at maturity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012066
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  • 7
    Electronic Resource
    Electronic Resource
    Sulphur uptake and distribution in double and single low varieties of oilseed rape (Brassica napus L.) (1993)
    Springer
    Plant and soil 150 (1993), S. 69-76 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00779177
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of sulphur nutrition on growth and nitrogen fixation of pea (Pisum sativum L.) (1999)
    Springer
    Plant and soil 212 (1999), S. 207-217 
    Details
    ISSN: 1573-5036
    Keywords: legume ; nitrogen ; N2-fixation ; pea ; sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A S-deficient soil was used in pot experiments to investigate the effects of S addition on growth and N2-fixation in pea (Pisum sativum L.). Addition of 100 mg S pot−1 increased seed yield by more than 2-fold. Numbers of pods formed were the most sensitive yield component affected by S deficiency. Sulphur addition also increased the concentration of N in leaves and stems, and the total content of N in the shoots. The amounts of N fixed by pea were determined at four growth stages from stem elongation to maturity, using the 15N dilution technique. Sulphur addition doubled the amount of N fixed at all growth stages. In contrast, leaf chlorophyll content and shoot dry weight were increased significantly by S addition only after the flowering and pod fill stage, respectively. Pea roots were found to have high concentrations of S, reaching approximately 10 mg g−1 dry weight and being 2.6–4.4 times the S concentration in the shoots under S-sufficient conditions. These results suggest that roots/nodules of pea have a high demand for S, and that N2-fixation is very sensitive to S deficiency. The effects of S deficiency on pea growth were likely to be caused by the shortage of N, due to decreased N2-fixation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004618303445
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  • 9
    Electronic Resource
    Electronic Resource
    Photodynamic therapy for treatment of cancers in oral and maxillofacial regions: a long-term follow-up study in 72 complete remission cases (1991)
    Springer
    Lasers in medical science 6 (1991), S. 201-204 
    Details
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Tumour ; Oral and maxillofacial regions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Seventy-two complete remission cases with tumours of the oral and maxillofacial regions treated by photodynamic therapy, which were followed-up long-term, are presented. The results were satisfactory. All of the 34 cases that have been followed-up for more than 5 years are alive, healthy and free of tumour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032549
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  • 10
    Electronic Resource
    Electronic Resource
    The use of Nd-YAG laser in the treatment of malignant tumours of the oral and maxillofacial regions (1991)
    Springer
    Lasers in medical science 6 (1991), S. 209-212 
    Details
    ISSN: 1435-604X
    Keywords: Nd-YAG laser ; Tumour ; Oral and maxillofacial region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Thirty cases with malignant neoplasms of the oral and maxillofacial regions treated by Nd-YAG laser are presented. All of them have been followed-up for 2–4 years, and the results are satisfactory. In 26 cases, the tumours disappeared clinically, were negative in pathological examination, and no recurrence was found in the 2–4 year follow-up period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032551
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