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  • 1
    ISSN: 1432-2013
    Keywords: Axonal connections ; Medullary respiratory neurons ; Pneumotaxic centre ; Termination of inspiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In urethane-anaesthetized, paralyzed and artificially ventilated rabbits, medullary respiration-related neurons (RRU) were classified according to the phase relation of their burst discharge to phrenic nerve activity. Phase-bound inspiratory (I) or expiratory (E) neurons were discriminated from phase-spanning expiratory-inspiratory (EI) or inspiratory-expiratory (IE) units. Mechanisms of termination of inspiration by electrical stimulation of rostral pontine nuclei (Nc. parabrachialis medialis; Lc. coeruleus) were examined firstly to demonstrate whether RRU receive descending excitatory and inhibitory afferents as well as ascending efferents and secondly to analyse the time course of the neuronal pathways involved. Of 120 RRU, 38 neurons were demonstrated to receive pontine afferents. About 33% of all E neurons became orthodromically excited during rostral pons stimulation whereas 18.2% of all I cells became orthodromically inhibited. Some RRU were shown to project up to the rostral pons. 50% of these were of the phase-spanning IE type. The onset of inspiratory inhibition induced by rostral pons stimulation occurred 3.4 ms after the onset of single electrical pulse stimulation. Based on these results a neuronal model for a pontine mechanism terminating inspiration is proposed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Axonal connections ; Control of breathing ; Medullary respiratory neurons ; Midbrain ; Reticular formation ; Rubrospinal tract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Suprapontine brain sites acting on the central respiratory system have been demonstrated to give rise to inspiratory as well as expiratory facilitatory effects. In the present study the inspiratory inhibitory effect which has been reported in the cat to be elicited consistently by electrical stimulation of the rubrospinal tract and the adjacent mesencephalic reticular formation was examined in the urethane-anaesthetized rabbit. Stimulation of these sites with single electrical shocks of moderate intensity induced a short latency (onset after 3.0 ms) transient (duration: 29 ms) inhibition of the phrenic nerve activity (PHR). Short volleys of stimuli applied in mid- to late-inspiration led to a premature off-switch of inspiration. The extracellularly recorded discharge activity of the different types of medullary respiration-related units (RRU) reflected these alterations, accordingly. Axonal connections of RRU with mesencephalic structures were evaluated. Examination of orthodromic responses of medullary RRU to stimulation of this pathway revealed that most bulbospinal inspiratory neurons (10 out of 13) were paucisynaptically inhibited after short latency (at least 1.2 ms). The conduction time from bulbospinal inspiratory neurons to the recording site of PHR was 1.6 ms. Thus, a disynaptic pathway — including bulbospinal inspiratory neurons — is suggested inducing inspiratory inhibition 3.0 ms after single shock midbrain stimulation. This inhibition results in disfacilitation of phrenic motoneurons. The fact that extensive electrolytic lesions of the pneumotaxic center in rostral pons did not abolish the observed inspiratory inhibitions excludes these structures from being involved. A direct pathway from the red nucleus and the adjacent reticular formation to phrenic nuclei of the spinal cord, however, can not be excluded from being involved in the demonstrated inspiratory inhibition. The described effects may play a role in behavioral or voluntary control of respiration.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0899-0042
    Keywords: chromatography ; chiral stationary phases ; separation of enantiomers ; CD spectra ; C4 and C2 symmetry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various possibilities to obtain intrinsically chiral calix[4]arenes are discussed. The enantiomers of three 1,3-dietheresters and one monoether compound derived from dissymmetric calix[4]arenes with C4 symmetry were separated by HPLC using chiral stationary phases and characterized by their CD spectra. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 13 (1982), S. 221-227 
    ISSN: 0933-5137
    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
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 697-713 
    ISSN: 0933-5137
    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: Wear and Fatigue at Rolling contacts and Counter MeasuresMachine parts subjected to rolling contact fatigue, i.e. gears or rolling element bearings, are exposed to a very particular stressing condition. No comparable condition will occur for other technical applications. These typical conditions and their effects on the material behaviour are described comprehensively. An introductional overview for this are of technical knowledge is given, in particular for engineers not so much experienced with respect to this matter. The most important phenomena influencing the behaviour of parts subjected to rolling contact fatigue are presented as well as the physics of damage initiation and the appearance of damaged parts. It is demonstrated exemplarily, how the analysis of the damaging processes can be used to take counter measures. The referencing to the public literature has been done in a way to enable the reader to easily find material for a further improvement of his knowledge for particular items.
    Notes: Wälzbeanspruchte Teile, wie Zahnräder und Wälzlager, unterliegen ganz charakteristischen Beanspruchungen, wie sie in anderen technischen Anwendungen nicht vorkommen. Diese besonderen Bedingungen und ihre Auswirkungen auf die Beanspruchungsverhältnisse und das Werkstoffverhalten werden ausführlich beschrieben. Vor allem Ingenieuren, die weniger mit dem Themenkomplex Wälzermüdung und -verschleiß vertraut sind, soll eine übersichtliche und gestraffte Einführung in dieses Gebiet gegeben werden. Hierzu werden die wichtigsten Einflußgrößen auf das verhalten wälzbeanspruchter Bauteile, der Ablauf einer eventuellen Schadensinitiierung und die Erscheinungsbilder verschiedener Ausfallsursachen dargestellt. An Beispielen wird gezeigt, wie sich aus der Analyse der Schädigungsabläufe Abhilfemaßnahmen herleiten lassen. Die Literaturhinweise sind so gewählt, daß sich der interessierte Leser in die einzelnen Themengebiete selbständig weiter vertiefen kann.
    Additional Material: 39 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 155-161 
    ISSN: 1434-193X
    Keywords: Mechanical bonding ; Interlocked molecules ; Template synthesis ; Calixarenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the amide-based rotaxane 7a bearing calix[4]arene blocking groups is described for the first time. While rotaxane formation fails if a calix[4]arene is functionalized at the upper rim with only an amino or methylamino group lacking any spacer, the prolonged amine 5a works successfully as stopper unit preventing dethreading of the dimeric wheel 1a by its size. Rotaxane formation of 8b was observed only by MALDI-TOF mass spectrometry of the reaction mixture of the amine 5b, the axle 6 and 1a. With the larger trimeric wheel 1b no stable rotaxane could be obtained. It either does not act as a concave template or its opening is too wide, even for the bulky calixarene stoppers.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Influence of Ligands on the Magnetic Ground State and the 1A1—5T2 Transition in Some Dithiocyanato-bis-diimine Iron(II) ComplexesA new series of pseudooctahedral complexes of the type [Fe(diimine)2(NCS)2] with the diimine ligands 1,10-phenanthrolin-4-n-butylester (I), 1,10-phenanthroline-4,7-di-n-butylester (II), 4,7-diphenyl-1,10-phenanthroline (III), 2,2′-dipyridyl-4,4′-di-n-butylester (IV), 2-pyridinealdehyd-N-isopropylimine (V) and 2-pyridinealdehyd-N-methylimine has been prepared. Magnetic susceptibility, Mössbauer parameters and IR spectra demonstrate the following types of physical behaviour in the solid state: gradual 1A1—5T2 transition with temperature, which goes to completion in (V), but which is interrupted untimely in (I) and (II). The compound (II) also contains an obviously constant part of molecules with S = 1. In (III), (IV), and (VI), on the other hand, there exists a constant and temperature independent ratio of molecules with S = 1 and S = 2 (“mixed spin solids”).
    Notes: Eine neue Reihe pseudooktaedrischer Komplexe des Typs [Fe(diimin)2 (NCS)2] mit den Diiminliganden 1,10-Phenanthrolin-4-n-butylester (I), 1,10-Phenanthrolin-4,7-di-n-butylester (II), 4,7-Diphenyl-1,10-phenanthrolin (III), 2,2′-Dipyridyl-4,4-di-n-butylester (IV), 2-Pyridinaldehyd-N-isopropylimin (V) und 2-Pyridinaldehyd-N-methylimin (VI) wurde dargestellt. Die magnetischen Suszeptibilitäten, die Mößbauer-Parameter und die IR-Spektren dieser Verbindungen zeigen, daß im Festzustand folgende Typen physikalischen Verhaltens vorliegen: Ein allmählicher, mit Änderung der Temperatur einsetzender 1A1—5T2-Übergang, der bei (V) vollständig verläuft, bei (I) und (II) jedoch vorzeitig abgebrochen wird. (II) enthält außerdem einen offenbar konstanten Anteil von Molekeln mit S = 1. Bei (III), (IV) liegt dagegen ein konstantes, temperaturunabhängiges Mischungsverhältnis von Molekeln mit S = 1 und S = 2 vor.
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 458 (1979), S. 69-73 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ligand Field Spectrum of Chromium(III)tris(dimethylphosphonium-bismethylide)The spectrum of the chromium(III)tris(dimethylphosphonium-bismethylide), [Cr{(CH2)2P(CH3)2}3], in heptane has been recorded under strictly anaerobic conditions, and the ligand field parameters derived from it, have been compared with the parameters of analogous complexes. The Δ value is nearly the same as with the [Cr(CH3)6]3--ion, and the comparatively smaller Racah parameter B probably can be attributed to a trigonal distortion from the ligand.
    Notes: Das Spektrum des Chrom(III)-tris(dimethylphosphonium-bismethylids), [Cr{(CH2)2P(CH3)2}3], in Heptan wurde unter anaeroben Bedingungen aufgenommen und die hieraus abgeleiteten Ligandenfeldparameter mit denen analoger Komplexe verglichen. Der Δ-Wert gleicht weitgehend dem des [Cr(CH3)6]3--Ions, der der vergleichsweise kleinere Racah-Parameter B ist dagegen vermutlich auf eine durch die Ligandenstruktur bedingte trigonale Störung des Ligandenfeldes zurückzuführen.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 486 (1982), S. 153-164 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Infrared-spectroscopic Characterization of Iron(II) Complexes with a Triplet Ground StateThe infrared spectra of [Fephen2(NCS)2] · 2 H2O and of some similar iron(II) complexes with a well defined triplet ground state have been studied between 4000 and 180 cm-1. In comparison to the i.r. spectra of [Fephen2(NCS)2] and related compounds with quintet and singlet ground states (corresponding to S = 2 and S = 0) it has been found that the bands typically for the 1.10-phenanthroline ligand are similar for S = 0 and S = 1, whereas the CN stretching vibrations of the thiocyanate and the metal-nitrogen stretching vibrations in the three ground states are different (ν1(SCN) for S = 1 2 056 cm-1, for S = 2 2 075 and 2 063 cm-1, for S = 0 2 116 and 2 108 cm-1; ν(Fe—N)(NCS) für S = 1 307 cm-1, for S = 2 252 cm-1, S = 0 533 and 529 cm-1; ν(Fe—N)(phen) for S = 1 374 and 360 cm-1, for S = 2 220 cm-1, for S = 0 379 and 371 cm-1). The differences in the infrared spectra are sufficient for the identification of the three ground states also in mixed spin iron(II) compounds.
    Notes: Die IR-Spektren des [Fephen2(NCS)2] · 2 H2O und einiger analoger Eisen(II)-Komplexe mit einem eindeutig definierten Triplett-Grundzustand wurden im Bereich von 4 000 bis 180 cm-1 ausführlich untersucht. Der Vergleich mit den IR-Spektren des [Fephen2(NCS)2] und ähnlicher Verbindungen mit einem Quintett- (S = 2) bzw. Singulett-Grundzustand (S = 0) zeigt, daß die für den 1.10-Phenanthrolin-Liganden typischen Banden sich für S = 0 und S = 1 wenig unterscheiden, während die CN-Valenzschwingung des Thiocyanatoliganden und ebenso die Metall-Stickstoff-Valenzschwingungen in den drei Grundzuständen deutlich voneinander verschieden sind (ν1(SCN) für S = 1 2 056 cm-1; für S = 2 2 075 und 2 063 cm-1; für S = 0 2 116 und 2 108 cm-1; ν(Fe—N)(NCS) für S = 1 307 cm-1, für S = 2 252 cm-1, für S = 0 533 und 529 cm-1; ν(Fe—N)(phen) für S = 1 374 und 360 cm-1, für S = 2 220 cm-1, für S = 0 379 und 371 cm-1). Die auftretenden Unterschiede reichen aus, um die drei Grundzustände anhand der IR-Spektren auch nebeneinander identifizieren zu können.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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