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  • 1
    Electronic Resource
    Electronic Resource
    Generator study of brainstem auditory evoked potentials by a radiofrequency lesion method in rats (1991)
    Springer
    Experimental brain research 85 (1991), S. 537-542 
    Details
    ISSN: 1432-1106
    Keywords: Generators ; Brainstem auditory evoked potentials ; Stereotaxic radiofrequency coagulation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The generators of brainstem auditory evoked potentials (BAEPs) in rats were investigated experimentally. Discrete lesions of the brainstem auditory pathway were made unilaterally using a stereotaxic radiofrequency coagulation method, and the BAEPs were recorded before and after the lesions to observe the alterations. The waves of the BAEPs were affected by the lesions as follows: (1) all of the BAEP waves were attenuated or eliminated by a lesion of the auditory nerve; (2) wave II was abolished or attenuated in amplitude following a lesion of the cochlear nucleus; (3) marked reduction or abolition of wave III occurred with some effect on waves IV and V following lesions of the superior olivary complex; (4) the following trough in the wave III was significantly attenuated by lesions of the lateral lemniscus that were associated with inconsistent changes in waves IV and V; (5) no waves were affected significantly by a lesion of the inferior colliculus. The method of radiofrequency lesion using stereotaxic localization proved to be a simpler and more rapid procedure for determining the generators of BAEPs in animals than other surgical lesion methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231737
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Miniemulsion polymerization of styrene stabilized by nonionic surfactant and reactive cosurfactant (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 1060-1067 
    Details
    ISSN: 1435-1536
    Keywords: Key words Miniemulsion polymerization ; nonionic surfactant ; reactive cosurfactants ; styrene ; emulsion stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary  A nonionic surfactant, nonylphenol polyethoxylate with an average of 40 ethylene oxides per molecule (NP-40), in combination with a reactive cosurfactant such as dodecyl methacrylate (DMA) or stearyl methacrylate (SMA) was used to prepare stable styrene miniemulsions in this study. Like conventional cosurfactants such as cetyl alcohol (CA) and hexadecane (HD), the reagent DMA or SMA may act as a cosurfactant in stabilizing the homogenized miniemulsions. Furthermore, the methacrylate group can be chemically incorporated into latex particles in subsequent miniemulsion polymerization, as shown by the IR spectra. The rate of Ostwald ripening for these miniemulsions in the decreasing order is: CA〉 DMA〉HD∼SMA. This trend correlates well with the water solubility of these cosurfactants. The lower the levels of NP-40 and DMA, the greater is the degree of Ostwald ripening. This is because the DMA concentration is not high enough to counteract diffusional degradation of monomer droplets. Polystyrene latex particles were produced via both monomer droplet nucleation and homogeneous (or micellar) nucleation for the system exhibiting strong Ostwald ripening and/or droplet coalescence during the very early stage of polymerization. On the other hand, monomer droplet nucleation becomes more important for the system showing weak Ostwald ripening. Temperature has an important influence on the shelf-life of miniemulsions and subsequent polymerization. This is attributed to the fact that hydrogen bonds between the polyethylene oxide part of NP-40 and water are quite sensitive to changes in temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050184
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Miniemulsion polymerization of styrene using alkyl methacrylates as the reactive cosurfactant (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 546-554 
    Details
    ISSN: 1435-1536
    Keywords: Key words Miniemulsion polymerization ; reactive cosurfactants ; styrene ; alkyl methacrylates ; emulsion stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Stable styrene miniemulsions were prepared by using alkyl methacrylates as the reactive cosurfactant. Like conventional cosurfactants (e.g., cetyl alcohol (CA) and hexadecane (HD)), alkyl methacrylates (e.g., dodecyl methacrylate (DMA) and stearyl methacrylate (SMA)) may act as a cosurfactant in stabilizing the homogenized miniemulsions. Furthermore, the methacrylate group may be chemically incorporated into latex particles in subsequent miniemulsion polymerization. The data of the monomer droplet size, creaming rate and phase separation of monomer as a function of time were used to evaluate the shelf-life of miniemulsions stabilized by sodium dodecyl sulfate in combination with various cosurfactants. Polystyrene latex particles were produced via both monomer droplet nucleation and homogeneous nucleation in the miniemulsion polymerization using CA or DMA as the cosurfactant, with the result of a quite broad particle size distribution. On the other hand, the miniemulsion polymerization with HD or SMA showed a predominant monomer droplet nucleation. The resultant particle size distribution was relatively narrow. In miniemulsion polymerization, the less hydrophobic DMA is similar to CA, whereas the more hydrophobic SMA is similar to HD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050117
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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