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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 361 (1998), S. 601-602 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Photoelectron spectroscopy on pyrolytic carbon films revealed a main part of carbon atoms in graphitic planes and a smaller part of functional groups with oxygen bonded to carbon atoms. Oxygen totalled a share of 10 at% and more of the carbon coating. The films with a turbostratic structure consist of nearly parallel oriented atomic layers of hexagonal rings with dimensions in the nanometer scale, which is well known from HREM investigations. The oxygen atoms are proposed to saturate the numerous dangling bonds around these individual atomic planes. The oxygen atoms form double bonds or bridges between carbon atoms.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 46 (1990), S. 1168-1172 
    ISSN: 1420-9071
    Keywords: Energy turnover ; anoxia ; twitch force ; passive force
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary ATP turnover of isolated rabbit papillary muscles, contracting isometrically at 20°C, was determined in oxygen and during 40 min of exposure to nitrogen (anoxia). Stimulus frequency was 0.2 hertz (Hz) in oxygen and 0.2 or 1.0 Hz in nitrogen. In oxygen, ATP turnover was determined from oxygen consumption using a P/O2 ratio of 6.3. The time-dependent rate of ATP turnover in nitrogen was found from the production of lactate, and the changes in adenine nucleotides and phosphocreatine, measured in rapidly frozen preparations at different time-points during the anoxic period. A P/lactate ratio of 1.5 was used. In muscles stimulated at 0.2 Hz, twitch force dropped during the anoxic period to 33% while force production of muscles stimulated at 1.0 Hz stopped completely. However, in the latter muscles, resting force rose to 19% of the twitch force in oxygen. The rate of ATP hydrolysis in anoxia depended strongly on stimulus frequency, indicating that it is not solely determined by the glycolytic capacity. In the 0.2 Hz-stimulated muscles the decrease in energy turnover occurred in parallel with the drop in force. However, the rise in resting force in muscles stimulated at 1.0 Hz occurred when ATP turnover was close to zero. It was concluded that anoxia hardly affects the energy required for twitch force production, but that the rise of resting force measured when twitch force had disappeared occurred when the rates of cross-bridge cycling and calcium turnover were very low.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The structure of a benthic microbial food web and its seasonal changes were studied in the shallow brackish waters of the island of Hiddensee, northeastern Germany, at two sites in close proximity by monthly or bimonthly sampling from July 1995 to June 1996. Abundance and biomass of phototrophic and non-phototrophic bacteria, heterotrophic flagellates (HF) and ciliates as well as the biomass of microphytobenthos were determined in the upper 0.3 cm sediment layer. Abundance of organisms showed strong positive correlation with water temperature, with the exception of the bacteria. Non-phototrophic bacterial numbers ranged from 7 × 108 to 6.7 × 109 cells cm−3 and phototrophic bacterial abundance from 4 × 107 to 2.7 × 108. Heterotrophic protist abundance ranged from 8 × 103 to 104 × 103 ind cm−3 for HF and from 39 to 747 ind cm−3 for ciliates. The biomass partitioning demonstrated the primary importance of non-phototrophic bacteria (min. 0.83, max. 84.87 μg C cm−3), followed by the microphytobenthos (min. 1.32, max. 50.93 μg C cm−3). The heterotrophic protists contributed roughly the same fraction to the total microbial biomass, with the biomass of the HF being slightly higher (HF 0.23 to 1.76 μg C cm−3, ciliates 0.04 to 1.17 μg C cm−3). Taxonomic classification of the benthic HF revealed the euglenids to be the most important group in terms of abundance and biomass, followed by thaumatomastigids and kinetoplastids. Other important groups were apusomonads, cercomonads, pedinellids and cryptomonads. The structure of the HF assemblage showed strong seasonal changes with euglenids being the most abundant taxa in summer, while apusomonads and thaumatomastigids were predominant in winter. Similar to the pelagic microbial food web, benthic picophototrophic bacteria were occasionally abundant, and the feeding modes of heterotrophic protists exhibited a great variety (predominantly omnivores, bacterivores, herbivores or predators). Filter-feeding HF were of little importance. Contrary to the pelagic environment, a top-down control on total benthic bacterial numbers by HF seemed unlikely at the studied stations which were characterised by muddy sand.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mineralium deposita 21 (1986), S. 337-339 
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Mineralium deposita 23 (1988), S. 238-238 
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 358 (1997), S. 105-107 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Crystalline strontium titanate layers were deposited on titanium anodes from Sr(OH)2 aqueous electrolyte solutions by a plasmachemical-electrochemical process of anodic spark deposition. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to study the properties of the polycrystalline material. Strontium titanate was deposited on the titanium anode surface as a ceramic layer from an aqueous electrolyte. The typical pore structure morphology of the anodic spark deposit (ASD) was characterized by SEM as well as fractures which provide an intimate contact between layer and substrate. XRD-study showed that the layers are composed of a mixture of SrTiO3 and TiO2.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 365 (1999), S. 255-257 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reinforcement effects in composites are widely influenced by fibre coatings. A detailed understanding of their microstructure and chemical composition is of great interest. Boron nitride films were deposited continuously on fibre rovings of various ceramics in CVD reactors of vertical as well as horizontal position. XPS depth profilings show that the film compositions are close to stoichiometric BN with carbon and oxygen impurities in the range of 10 at%. Cross-sections of separated fibres were investigated by HREM and TEM diffraction. All BN films are hexagonal turbostratic. The (002) layers with an increased distance (about 0.36 nm) showed a mean stacking sequence near to graphite and a characteristic orientation to the fibre in the interface region. We assume the gas flow type and hence the exchange rate of matter and energy determines the film structure in this region. With increasing film thickness the (002) layers fold randomly in all directions or form nanocrystals at elevated temperatures.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Child Abuse & Neglect 14 (1990), S. 337-345 
    ISSN: 0145-2134
    Keywords: Child's defiance ; Emotional distress ; Environmental stress ; Justification of abuse
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Psychology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Sensors and Actuators A: Physical 39 (1993), S. 261-262 
    ISSN: 0924-4247
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 11 (1999), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Human temporal lobe epilepsy is characterized by strong synaptic reorganization that leads to abnormal recurrent excitatory synaptic connections among hippocampal neurons. In addition, electrophysiological studies show that synaptic activity of the main afferent input to the hippocampus, the perforant path, is prolonged and amplified by changes in postsynaptic glutamate receptors. The current view is that these morphological and physiological abnormalities contribute significantly to the hyperexcitability seen in the hippocampus of temporal lobe epilepsy. Recently, it was found that presynaptic inhibitory metabotropic glutamate receptors are an important negative feedback mechanism that controls synaptic release of glutamate in the hippocampus. In this study, we assessed the functionality of this feedback system by investigating the metabotropic glutamate receptor mediated depression of excitatory synaptic transmission in surgically removed hippocampi from patients with marked synaptic reorganization (Ammon's horn sclerosis group) and from patients without detectable reorganization (lesion group). We report here that this control of synaptic transmission is lost in hippocampi from the Ammon's horn sclerosis group whereas this control is preserved in hippocampi from the lesion group. The data presented here suggest that the loss of feedback inhibition mediated by metabotropic glutamate receptors could be a further, previously not recognized, mechanism in the pathophysiology of temporal lobe epilepsy.
    Type of Medium: Electronic Resource
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