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  • Polymer and Materials Science  (17)
  • Industrial Chemistry  (3)
  • 82.65  (2)
  • Autoreceptors  (2)
  • 1
    ISSN: 1432-1912
    Keywords: Key words Microdialysis ; 5-HT release ; Chronic antidepressant ; Citalopram ; 5-HT reuptake inhibitor ; Tolerance ; Autoreceptors ; Frontal cortex ; Dorsal hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rats were administered the selective serotonin (5-HT) uptake blocker citalopram or saline for 14 days to determine if prolonged treatment would lead to changes in extracellular 5-HT or autoreceptor sensitivity. One day after drug withdrawal, dialysis probes were implanted in the frontal cortex and dorsal hippocampus. Dialysis experiments were carried out using chloral hydrate anesthetized rats. The experimental protocol comprised the administration of three consecutive drug challenges: (1) After stable baseline levels were obtained, citalopram was infused through the dialysis probes to locally block uptake in the forebrain. (2) Subsequently, a 5-HT1B receptor agonist (RU24969 or CP93,129) was infused through the probe to test for changes in terminal autoreceptor sensitivity. (3) Last, citalopram was administered systemically to test the effect of indirect activation of somatodendritic autoreceptors. Under these conditions, with uptake already blocked locally in the forebrain, systemic citalopram produces a decrease in extracellular 5-HT, an effect that can be inhibited by pretreatment with antagonists of 5-HT1A receptors. The results indicate that during local infusion of citalopram extracellular 5-HT was significantly higher in the dorsal hippocampus of the chronic citalopram as compared to saline treatment group. This difference persisted throughout the full time course of the experiment. However, the decreases in 5-HT levels produced by local infusion of a 5-HT1B receptor agonist or after systemic citalopram administration were not significantly different between the chronic citalopram and saline treated groups. There were no significant differences between chronic citalopram and saline treated animals in frontal cortex. These results suggest that prolonged inhibition of 5-HT uptake may produce a selective change in the regulation of release from median raphe 5-HT neurons, but this change could not be clearly linked to a change in nerve terminal or somatodendritic autoreceptor sensitivity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1912
    Keywords: Microdialysis ; 5-HT release ; Chronic antidepressant ; Citalopram ; 5-HT reuptake inhibitor ; Tolerance ; Autoreceptors ; Frontal cortex Dorsal hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were administered the selective serotonin (5-HT) uptake blocker citalopram or saline for 14 days to determine if prolonged treatment would lead to changes in extracellular 5-HT or autoreceptor sensitivity. One day after drug withdrawal, dialysis probes were implanted in the frontal cortex and dorsal hippocampus. Dialysis experiments were carried out using chloral hydrate anesthetized rats. The experimental protocol comprised the administration of three consecutive drug challenges: (1) After stable baseline levels were obtained, citalopram was infused through the dialysis probes to locally block uptake in the forebrain. (2) Subsequently, a 5-HT1B receptor agonist (RU24969 or CP93,129) was infused through the probe to test for changes in terminal autoreceptor sensitivity. (3) Last, citalopram was administered systemically to test the effect of indirect activation of somatodendritic autoreceptors. Under these conditions, with uptake already blocked locally in the forebrain, systemic citalopram produces a decrease in extracellular 5-HT, an effect that can be inhibited by pretreatment with antagonists of 5-HT1A receptors. The results indicate that during local infusion of citalopram extracellular 5-HT was significantly higher in the dorsal hippocampus of the chronic citalopram as compared to saline treatment group. This difference persisted throughout the full time course of the experiment. However, the decreases in 5-HT levels produced by local infusion of a 5-HT1B receptor agonist or after systemic citalopram administration were not significantly different between the chronic citalopram and saline treated groups. There were no significant differences between chronic citalopram and saline treated animals in frontal cortex. These results suggest that prolonged inhibition of 5-HT uptake may produce a selective change in the regulation of release from median raphe 5-HT neurons, but this change could not be clearly linked to a change in nerve terminal or somatodendritic autoreceptor sensitivity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 14 (1977), S. 141-147 
    ISSN: 1432-0630
    Keywords: 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have determined by direct molecular beam velocity measurements that translational energy accommodation of O2 molecules scattered from a hot polycrystalline tungsten target is inefficient at high surface temperatures. Translational energy accommodation is inefficient whether the surface is clean or covered with oxygen to a varying extent, even though in the latter case the scattering is diffuse. On a clean tungsten surface the scattering of the O2 was approximately specular and the reaction probability of O2 was constant and greater than 90% over the temperature range 1000K to 2800 K. It was shown by simultaneous helium scattering that atomic surface roughness of an oxygen chemilayer, rather than trapping, is a major cause of the observed diffuse scattering of oxygen. At the lowest surface temperature of 1000 K, with an oxygen chemilayer present, the velocity of the most probable number density of the scattered O2 was lower than in the incoming beam or than that expected for complete equilibration with the surface.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 14 (1977), S. 411-413 
    ISSN: 1432-0630
    Keywords: 82.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A direct first step in the mechanism for the initial oxidation of a polycrystalline tungsten surface, the catalyzed dissociation of O2 on it, or the formation of WO X by O2 at intermediate temperatures is shown to occur in ∼10−13 s. Molecular beam experiments demonstrated that the reactivity was greater than 90%, the unreacted O2 was substantially unaccommodated in translational energy to the surface temperature, and the reaction probability was nearly independent of surface temperature from 2800 to 415 K although there was a small increase at 415 K. The general conditions when no molecular surface precursor state contributes to the surface reactivity are discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 25 (1953), S. 343-344 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Es werden Apparaturen zur Zerteilung von Gasen in Flüssigkeiten sowie der Wirkungsbereich dieser Anordnungen besprochen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 23 (1951), S. 1-2 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Unter Akustochemie wird die Erzeugung von Schall beliebiger Frequenz durch chemische Energie und umgekehrt die Beeinflussung chemischer Reaktionen durch akustische Schwingungen verstanden. Schallsender mittels periodischer Explosionen, welche elektrisch, mechanisch oder durch Selbsterregung gesteuert sind, werden beschrieben.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 24 (1952), S. 259-261 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Einleitend wird auf den grundsätzlichen Aufbau und das Frequenz-Einsatzgebiet der verschiedenen Schwingungserreger eingegangen. Die wirtschaftliche Bedeutung kommt dem niederfrequenten Bereich zu. Zum Unterschied von Rührwerken treten bei Vibrationen starke Beschleunigungskräfte auf, deren Auswirkung besonders bei heterogenen Systemen von Interesse ist. Neben einer von der Frequenz abhängigen Mindest-Amplitude ist für das Fördern und Klassieren die mehr oder weniger elastische Reflexion des Materials auf seiner Unterlage verantwortlich.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1,3,5-Trioxane (1) and 1,3-dioxep-5-ene (2) were copolymerized with BF3OEt2 at 65°C. The products, after base hydrolysis, were characterized by 13C and 1H NMR and were found to assume the chemical structure 4 of a copolymer containing oxymethylene and oxy-2-butenylene units with 4-hydroxy-2-butenyl and methoxy end groups, with the ratio of hydroxy-2-butenylene to methoxy end groups varying with experimental conditions. The copolymer demonstrates crystallinity and thermal stability comparable to poly(trioxane-co-ethylene oxide)s. Copolymer melting point was observed to decrease with increasing comonomer incorporation. The upper limit for incorporation of the comonomer 2 was found to be ca. 4 mol per cent. Viscosity and end group analysis (by 1H NMR) indicate molecular weights in the range of 104 to 105. The comonomeric unit demonstrates the ability to act as both a stopper against unzipping and as a trap for certain degrading agents.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 2 (1951), S. 365-367 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Phase boundary-lines, especially in their impotance for corrosionTwo phases have a common cleavageplane, whilst three phases touch one another along a boundary line only. Corroesponding to an adsorption in the first case in an adlineation in the second case. Both processes diminish the free energy and herewith the activity of the boundary, so inhibiting the possibilities of corrosion.Local elements, glow cathodes and catalysts consisting of several components are typical systems acting at microscopic boundary-lines. Cavitation is the inverse phenomenon.Macroscopic boundary-lines in partially filled containers, formed by wall, liquor and gaseous phase, are about this especially active, as being mixed with a four-phases-point-system, that results from the heterogeneity of the container wall. Gravity potentials, and electrokinetic potentials have their maximum value in the boundary-lines too.
    Notes: Zwei Phasen haben eine gemeinsame Grenzfläche, während drei Phasen sich nur entlang einer Grenzlinie berühren. Der Adsorption im ersten Falle entspricht eine Adlineation im zweiten Falle. Beide Vorgänge setzen die freie Energie und damit die Aktivität der Grenze herab, hemmen also Korrosionsmöglichkeiten.Lokalelemente, Glühkathoden und Mehrstoff-Katalysatoren sind typische Systeme, die an mikroskopischen Grenzlinien zur Wirkung kommen. Kavitation bildet die inverse Erscheinung hierzu.Makroskopische Grenzlinien an teilgefüllten Behältern, die durch Wandung, flüssigem Inhalt und gasförmiger Phasegebildet werden, sind darüber hinaus besonders aktiv, da sie von einem Vierphasen-Punktsystem durchsetzt sind, das infolge er heterogenität der Behälterwand resultiert.Gravitationspotentiale und elektrokinetische Potentiale haben ebenfalls in den begrenzenden Linien ihren maximalen Wert.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 5 (1954), S. 359-359 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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