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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is demonstrated that the decay-rate plot method is a good means for estimating Touschek effect and ion clearing. The computer-processed decay-rate plot against stored current I is very useful for indicating the decay mode (I or II) changing with local pressure conditions of a storage ring and to evaluate the 1/e lifetime of the stored beam current. At decay mode I, the decay rate is roughly proportional to I2 and at decay mode II the decay rate is proportional to I. Generally speaking, the ion clearing can reduce the decay rate and longer lifetime can be achieved at the higher beam current. However, when a local- and current-independent high-pressure gas is present in a storage ring, the experimental results show that the decay mode is changed from I to II at low currents below a threshold current by ion clearing and that threshold current depends on a level of local pressure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The heat capacity changes (ΔCp) at the glass transition in mixed-alkali tellurite glasses of (20-x)Li2O-xNa2O-80TeO2 that show different fragilities, depending on the Na2O/Li2O ratio, have been measured to obtain more-detailed information on the structure of tellurite glasses or supercooled liquids with a fragile character. A large increase in Cp is clearly observed at the glass transition in all the samples. The values of the heat capacity of glasses and supercooled liquids (Cpg and Cpe, respectively) and ΔCp (equal to Cpe-Cpg) at the glass transition temperature, Tg, are almost the same, irrespective of the Na2O/(Na2O+Li2O) ratio, indicating the absence of a clear, mixed-alkali effect on Cp at Tg. The values of Cpg at 200°C, Cpe at 300°C, and ΔCp at Tg are } 75, 120, and 45 J·(mol·K)−1, respectively. The ratio of the heat capacity of the glassy state to the heat capacity of the supercooled liquid state, i.e., Cpe/Cpg, is 1.6; this large value indicates that the (20-x)Li2OxNa2O80TeO2 system should be included in the category of fragile liquids. It has been suggested that the structural units of TeO4 trigonal bipyramid and TeO3 trigonal pyramid are weakly connected to each other and, thus, the intermediate structure varies largely as the temperature increases, which leads to a fragile character. The change in the fragility that is caused by the mixing of dissimilar alkali ions is not detected through ΔCp (i.e., there is no mixed-alkali effect on thermodynamic fragility); however, it is observed from the viscosity behavior at } }Tg (i.e., the presence of the mixed-alkali effect on kinetic fragility).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 4761-4761 
    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
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 1913-1924 
    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 effect of the structure of carbon black aggregates on the melt behavior and electrical conductivity of carbon black-vinylchloride-vinylacetate copolymer systems was analyzed. As the amorphous carbon aggregates are roll-milled, they become cylindrical, then, as the milling time is prolonged, spherical. During milling, polymer adsorption and dispersivity increases in the same manner, causing the viscosity of the composite to decrease. It was established that during a certain milling time, conductivity rises to a peak, after which it falls. We attribute this phenomenon to there being an optimum aspect ratio and degree of dispersion of the cylindrical carbon aggregates. A model explaining the relationship between milling time and change in conductivity is proposed. When oxidized carbon black was dispersed into the copolymer, it was found that it disperses better than unoxidized carbon black, although the conductivity of the resulting composite is lower.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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