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  • 1
    Electronic Resource
    Electronic Resource
    Effects of stimulation of frontal cortex, superior colliculus, and neck muscle afferents on interstitiospinal neurons in the cat (1981)
    Springer
    Experimental brain research 44 (1981), S. 143-153 
    Details
    ISSN: 1432-1106
    Keywords: Interstitiospinal neurons ; Pericruciate cortex ; Frontal eye fields ; Superior colliculus ; Neck muscle afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Interstitiospinal neurons were activated by antidromic stimulation of the spinal cord ventromedial funiculus at C1 and C4 in cerebellectomized cats under chlor alose anesthesia. Neurons responding only to C1 were classified as N cells and those responding both to C1 and C4 were classified as D cells, as in previous experiments (Fukushima et al. 1980a). Vestibular branching interstitiospinal and reticulospinal neurons were also identified as in the previous experiments. Stimulation of the ipsilateral pericruciate cortex evoked firing in 31% of N cells, 41% of D cells and 35% of vestibular branching neurons, while stimulation of the contralateral cortex excited 6% of N cells, 29% of D cells and 14% of vestibular branching neurons. Response latencies ranged from 2 to 15 ms after the effective pulse. By measuring the thresholds of activation of these neurons while changing the depth of the stimulating electrodes, and by mapping the cortical areas, it was shown that the lowest threshold areas were in the frontal eye fields and the anterior sigmoid gyrus near the presylvian sulcus (Area 6). Stimulation of the latter area often evoked neck or shoulder muscle contraction. Stimulation in the deep layers of the ipsilateral superior colliculus evoked firing in about 20% of interstitiospinal neurons and about 42% of vestibular branching neurons, with typical latencies 2–3 ms after the effective pulse, while stimulation of the contralateral superior colliculus was rarely effective. N cells and D cells responded similarly. Thresholds for activation were high in the intermediate tectal layers and declined as the electrodes entered the underlying tegmentum. This suggests that the superior colliculus is not the main source of synaptic inputs to these neurons. Low threshold points were found above the deep fiber layer when stimulating electrodes were inserted into the pretectum. Stimulation of the C2 biventer cervicis nerve excited about 8% of N cells, 18% of D cells, and 15% of vestibular branching neurons bilaterally with typical latencies around 10 ms. Similar results were obtained when C2 splenius nerves were stimulated. The fibers responsible for such excitation are probably group II, since stimuli stronger than 1.8 times threshold of the lowest threshold fibers were needed to evoke excitation. Response decrement was often observed when stimuli were repeated at 1/s, while no such decrement was observed at the rate of 1/3 s. When the convergence of cortical and labyrinthine excitatory inputs was studied, 36% of interstitiospinal neurons received single inputs either from the pericruciate cortex or from the labyrinth, 22% of neurons received convergent excitation from both and the remaining 42% did not respond to either stimulus. Although vestibular branching neurons rarely received labyrinthine inputs, they frequently showed convergence of excitation to stimulation of the frontal cortex, superior colliculus and vestibular nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237335
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanochemical polymerization of acetylene (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 3445-3455 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Gamma alumina, γ-Al2O3, was fractured in an atmosphere of acetylene monomer at room temperature to test whether they would be polymerized by mechanochemistry method on the surface of the alumina. The experimental results were obtained by serveral different methods, including CP-MAS 13C-NMR, ESR, pressure drop measurements of the monomer, optical absorption spectroscopy, and solvancy. The results proved the mechanochemical polymerization of acetylene monomer on surfaces of the fractured alumina. Several other combinations of either silica and acetylene monomer or polymers and acetylene monomer were tested for mechanochemical polymerization. This process proceeded with less efficiency in the silica system but no mechanochemical polymerization of acetylene was found in the combinations of the polymers and acetylene monomer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291121
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  • 3
    Electronic Resource
    Electronic Resource
    Polymerization of ethylene induced by fractured metallic oxides. III. Factors affecting the polymerization (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 3401-3408 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Mechanochemical polymerization of ethylene was found to be induced by fracture of γ-alumina under quite low pressure and room temperature. The factors to control the polymerization yield, for example, calcination temperature of the alumina, spin concentration after ball milling, milling time, and changes of acidity before and after the fracture, were investigated in order to know the polymerization mechanism. It was found that the polymerization yield did correlate not with the spin concentration responsible to paramagnetic species produced by the fracture, but the calcination temperature of the γ-alumina and the milling time. The resultant polymeric material on the fractured alumina was extracted alumina was extracted with solvents, and the fraction extracted with petroleum ether was characterized using GC and GC mass spectrometer. The results indicated that odd-numbered linear hydrocarbons were produced, although the major products of this polymerization were even-numbered. It is concluded from the accumulated experimental results that a carbonium ion mechanism rather than radical mechanism is probable for the mechanochemical polymerization induced by fracture of γ-alumina.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291117
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