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  • 1990-1994  (6)
  • 1992  (6)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 147-150 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The phenomenon of electrical degradation in ZnO varistors was studied by application of high-intensity current pulses. A wave shape of 8×20 μs and rectangular waves of 1 and 2 ms were used. The degradation was estimated by reference electric-field variation and by Schottky voltage barrier deformation. The results showed that current pulses reduce both the height and the width of the barrier voltage. It was also observed that the donor density Nd did not change but the surface states density Ns decreased with degradation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0972
    Keywords: Aroma ; compound ; Saccharomyces cerevisiae ; wine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Fourteen strains of the yeastSaccharomyces cerevisiae were isolated from three wineries in the Salnés wine region (N.W. Spain) at the three different periods of the natural fermentation. Each wild yeast was screened for production of acetaldehyde, ethyl acetate, isobutanol,n-propanol, amylic alcohol and other important enological compounds during laboratory scale fermentations of grape juice. After 25 days at 20°C, the analytical results evidenced variations in the production of acetaldehyde (from 13.1 to 24.3 mg/l), isobutanol (from 27.7 to 51.1 mg/l), amyl alcohols (from 111 to 183 mg/l) and ethyl acetate (from 19.3 to 43.7 mg/l). Although isolated from the same wine region, differences in the wine composition were observed depending on the particular yeast strain used for the vinification experiments.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-0972
    Keywords: Curing ; fermentative behaviour ; killer ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Fermentative behaviour and cell growth have been studied in grape juice inoculated either with two killerSaccharomyces cerevisiae wild strains or with their Acridine Orange-cured isogenic counterparts. The number of viable cells/ml at the beginning of the fermentation, as well as during exponential growth, were higher in grape juices inoculated with the cured strains. The CO2 production, fermentative rate and ethanol and acetic acid production were also higher in the cured strains, particularly during the stage of active fermentation. These differences, however, were minimal at the end of the fermentations.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International urogynecology journal 3 (1992), S. 12-17 
    ISSN: 1433-3023
    Keywords: GSI surgical treatment ; Retropubic vaginal urethropexy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a 5-year experience performing vesicovaginal fascial sling operation (VVFSO) for the treatment of genuine stress incontinence associated with prolapse. This original technique, plus others to correct prolapse, was employed in 41 women evaluated preand postoperatively with traditional clinical and urodynamic methods. Essentially the procedure is a transvaginal retropubic urethrocystopexy by means of two fascial strips, obtained from the central part of the cystocele, crossed beneath the urethrovesical junction and fixed to the periostium of the lower retropubis on each side. All 41 patients were followed for 1–5 years, with 39 of them cured (95.1%) and 2 failed (4.9%). A significant postoperative increase in the maximal urethral closure pressure, from 10–35 cmH2O with a mean of 18, was found. The VVFSO is an easy vaginal procedure, which provides a high success rate in correcting GSI associated with prolapse.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 27 (1992), S. 5325-5329 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The electrical degradation phenomena of zinc oxide-based varistors were studied using a high-energy current pulse and a.c. polarization at different temperatures. Activation energy measurements during the degradation process showed that these phenomena are associated with diffusion and that the diffusion-controlling species are slower than Zn., For degradation promoted by current pulses of 8×20 μs, the Schottky potential barrier deformation was measured. A decrease in height and width of the potential barrier due to the reduction of surface states density,N s, without a significant change in donor density,N d, was observed. To explain these results, a modification of the unstable components model is proposed for the potential barrier in which the degradation is due to oxi-reduction reactions between atomic defects. These reactions promote the elimination of zinc vacancies and/or adsorbed oxygen on the grain boundaries.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 27 (1992), S. 5325-5329 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The electrical degradation phenomena of zinc oxide-based varistors were studied using a high-energy current pulse and a.c. polarization at different temperatures. Activation energy measurements during the degradation process showed that these phenomena are associated with diffusion and that the diffusion-controlling species are slower than Zn., For degradation promoted by current pulses of 8×20 μs, the Schottky potential barrier deformation was measured. A decrease in height and width of the potential barrier due to the reduction of surface states density,N s, without a significant change in donor density,N d, was observed. To explain these results, a modification of the unstable components model is proposed for the potential barrier in which the degradation is due to oxi-reduction reactions between atomic defects. These reactions promote the elimination of zinc vacancies and/or adsorbed oxygen on the grain boundaries.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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