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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of MPTP-induced changes in spontaneous neuronal discharge in the internal pallidal segment and in the substantia nigra pars reticulata in primates (1999)
    Springer
    Experimental brain research 125 (1999), S. 397-409 
    Details
    ISSN: 1432-1106
    Keywords: Key words Substantia nigra ; MPTP ; Parkinsonism ; Primate ; Electrophysiology ; Basal ganglia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The basal ganglia are currently viewed as components of segregated corticosubcortical reentrant circuits. One of these circuits, the ”motor” circuit, is critically involved in the development of parkinsonian motor signs. Current pathophysiologic models postulate that parkinsonism is associated with increased activity in the basal ganglia output nuclei. The neuronal activity in the motor portion of one of these output nuclei, the internal segment of the globus pallidus (GPi), has been characterized in detail in intact and parkinsonian animals, but the neuronal activity in the second major basal ganglia output nucleus, the substantia nigra pars reticulata (SNr), has received far less attention. This study in primates represents a comparison of the effects of parkinsonism, induced by injections of the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), on the neuronal discharge in the GPi and SNr. These electrophysiologic recording experiments were carried out in three African green and two rhesus monkeys. One hundred and twenty-four neurons were recorded in the GPi before treatment with MPTP, and 93 neurons thereafter. In the SNr, 55 cells were recorded before treatment with MPTP, and 41 cells thereafter. MPTP induced a non-significant increase in the average discharge rate and a significant decrease in the median interspike interval length (ISI) in the GPi (by 13%), whereas no changes were detected in either parameter in the SNr. The average ISI distributions were markedly asymmetric in both structures, and could be modeled by a logarithmic normal distribution. With the MPTP treatment, the mode of the ISI distribution fell by 24% in the GPi (P≤0.01), whereas it did not change significantly in the SNr. An algorithm that detects burst discharges in the raw ISI data (based on the method by Legendy and Salcman) detected a significant increase in the proportion of action potentials that participated in bursts of discharge in both structures (increase by 257% in the GPi, and by 67% in the SNr). Power spectral and autocorrelation analysis revealed that treatment with MPTP increased the proportion of cells with oscillatory burst patterns at 3–8 Hz in both structures (from 0.8% to 27% of all neurons in the GPi, and from none to 10% in the SNr). The results show that neuronal discharge in the SNr is affected in parkinsonism, but that the changes in the SNr are less pronounced then those seen in the GPi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050696
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of ethylene-propylene rubber and ethylene-propylene-diene rubber networksPart of this work has been presented to the Rubber Division of ACS in Cleveland, Spring Meeting, 1968. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 145-153 
    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: The stress-strain (S/S) and the swelling equilibrium behavior in a series of ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) networks were investigated and the results were employed to evaluate the effects of varying the cure conditions on the crosslinking efficiency in these networks. The S/S curve of completely swollen vulcanizates is in agreement with the predictions of rubber elasticity theory, while that of dry or partially swollen vulcanizates is fully described by the Mooney-Rivlin equation. ϰ values determined in benzene were found to vary linearly with vr (vr = equilibrium volume fraction of rubber in swollen sample). Crosslinking efficiency, moles of crosslinks produced per moles of crosslinking agent used, ranges from 3.7 in peroxide-cured EPDM (55% wt ethylene and 2.6% unsaturation) to 0.15 in similarly cured EPR (43% ethylene). Efficiency in the latter system improves to 0.6 by addition of a coagent (sulfur) to the cure formula. Crosslinking efficiency in EPDM (55% ethylene) was found to increase in the order: peroxide- 〉 resin- 〉 sulfur-cured. In the EPDM sulfur vulcanizates, changing the terpolymer in the cure formula resulted in significant changes in the crosslinking efficiency.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1971.070150113
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of NBR networks from stress-strain and swelling equilibrium measurementsPresented in part at American Chemical Society Third Middle Atlantic Regional Meeting, February 1-2, 1968, Philadelphia, Pennsylvania. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1837-1850 
    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: An improved stress-strain (S/S) method based on rubber elasticity theory and swelling equilibrium measurements was used to investigate the S/S behavior and the solvent swelling properties of nitrile-butadiene rubber (NBR) and also to study the effects of varying the cure agent and the curing conditions on the crosslinking efficiency in NBR vulcanizates. The S/S curve of completely swollen NBR vulcanizates is, as expected, in agreement with rubber elasticity theory, while that of dry or partially swollen vulcanizates is well described by the Mooney-Rivlin equation. Determined in benzene, χ was 0.494, compared to 1.338 in cyclohexane and 2.124 in n-heptane. The degree of crosslinking and the crosslinking efficiency in the NBR vulcanizates, moles of crosslinks produced per mole of crosslinking agent employed in the formula, are largely dependent on the nature of the crosslinking agent used and increase in the following order: peroxide, sulfur tetramethylthiuram disulfide, sulfur N-cyclohexyl-2-benzothiazolesulfenamide, sulfur benzothiazyl disulfide, and finally tetramethylthiuram disulfide.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1971.070150803
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  • 4
    Electronic Resource
    Electronic Resource
    Gel permeation chromatography: On the shape of the calibration plot and molecular size separability (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 5 (1967), S. 569-581 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Data obtained from the calibration of GPC columns of different permeabilities with standard polystyrenes are reported. For single columns the logarithm molecular weight-elution volume plot is linear for approximately one and one-half decades in molecular weight. GPC separations are such that the separability of two samples of similar molecular weight improves as their mean molecular weight decreases. Because of this the analysis of high molecular weight polymers can best be accomplished on a series of columns in which each column has a high permeability limit. The elution volume for columns in series is shown to be the sum of the elution volumes of the individual columns. As higher molecular weights are eluted a pronounced tailing effect is observed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.160050314
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  • 5
    Electronic Resource
    Electronic Resource
    The physical chemistry of dyeing. Thomas Vickerstaff. Published for Imperial Chemical Industries Ltd. by Oliver and Boyd, London and Edinburgh, and Interscience, New York, 1950. viii + 416 pp., $7.50 (1951)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 6 (1951), S. 779-779 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1951.120060617
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of moisture-cured polyurethane films (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 1591-1601 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of polyurethanes (PU) prepolymers with NCO/OH ratios of 2.1:1 and 1.9:1 were prepared by reacting hydrogenated methylene di-p-phenyl diisocyanate (HMDI) with triol mixtures of TP740 (molecular weight 740) and TP1540 (molecular weight 1540). Stress-strain (S/S) and swelling equilibrium measurements were performed using thin-film samples prepared by moisture-curing the prepolymer at room temperature. The swollen PU networks gave an S/S curve which is fully described by rubber elasticity theory. The Mooney-Rivlin constant C1 (swollen) was found to increase directly while the molecular weight between crosslinks Mc decreases as the number of branches per cubic centimeter is increased. The solvent - polymer interaction parameter χ determined in benzene was 0.077 + 0.97vr, where vr is the volume fraction of rubber in the swollen network. The crosslink density v′, and Mc were calculated from the relations v′ = pNB and Mc = 0.667 B-1, where B denotes moles of branches per gram, and were found to be in good agreement with v′ and Mc established from S/S and swelling-equilibrium measurements. In calculating v′ and Mc, the water-PU crosslinking reaction at room temperature was assumed to occur mainly through the formation of a urea linkage.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.160090904
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  • 7
    Electronic Resource
    Electronic Resource
    Gel permeation chromatography applied to polymer adsorption studies (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 7 (1969), S. 529-533 
    Details
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.110070708
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