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  • 2-methyl-tetrahydrofuran  (1)
  • Computed tomography  (1)
  • 1
    ISSN: 1432-1920
    Schlagwort(e): Tuberous sclerosis ; Magnetic resonance ; Computed tomography ; Demyelination ; Mental retardation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of the disease. T2 weighted spin echo (TR=1800, TE=120) images and inversion recovery (TR=2100, TI=500–600, TE=40) images were obtained at the same axial planes. Periventricular nodules were better seen, because of their calcifications, with CT than with MR imaging. They were demonstrated as iso- to low intensity depending on the amount of calcification on T2 weighted images, and as a similar intensity to the white matter on IR images. Small peripheral lesions in the hemispheres, which were only occasionally seen as small low density areas on CT scans, were well demonstrated on MR images. These foci were hyperintense on T2 weighted images, and hypointense on IR images. Exact location of these was not in the cortex, but in the subcortical white matter. The findings indicate that these foci represent the pathologically well known demyelinating foci, which are commonly present under the cortical tuber, but may be independent of them. Cortical tubers were not confidently identified, which suggested that they might have similar intensity to the cortical gray matter. Some of the parenchymal calcifications other than periventricular nodules showed identical MR signal intensities to periventricular nodules, and the rest of the parenchymal calcifications had similar intensities to the subcortical lesions. This indicates that parenchymal calcifications can occur in the demyelinating white matter as well as in the heterotopic tubers in the white matter. The severely mentally retarded patients tended to have a higher number of subcortical lesions and no correlation was noted between the severity of mental retardation and either the number of periventricular nocules or ventricular dilatation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of applied electrochemistry 29 (1999), S. 789-796 
    ISSN: 1572-8838
    Schlagwort(e): 2-methyl-tetrahydrofuran ; cell safety ; ethylene carbonate ; lithium cell ; organic electrolyte ; propylene carbonate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The influence of electrolyte composition on the cycling performance and safety of AA rechargeable cells with a lithium metal anode, and an amorphous (a-) V2O5-P2O5 cathode was examined. The cells were cycled at a discharge current of 1000 mA and a charging current of 200 mA. The electrolytes were composed of ethylene carbonate (EC)/2-methyltetrahydrofuran (2MeTHF) binary and EC/propylene carbonate (PC)/2MeTHF ternary mixed solvents containing 40–70 vol% 2MeTHF to provide higher conductivity. The solute was 1.5mol dm−3 LiAsF6. The cycle life of the AA cells was evaluated by setting the end of cycle life at the cycle number where the discharge capacity fell to 50% of its maximum value. Cells with EC/2MeTHF (50:50) exhibited the longest cycle life among all the electrolytes examined here. Cells with EC/PC/2MeTHF (15:45:40) had the longest cycle life among the ternary mixed solvents systems. Fundamental abuse tests were also carried out on AA cells, which were cycled twice (fresh cells), cycled 100 times and cycled until the end of their cycle life. Neither the fresh nor the cycled cells with EC/PC/2MeTHF (15:45:40 ) smoked nor ignited in a 150 °C heating test or in an external short circuit test. However, the fresh cell with EC/2MeTHF (50:50) ignited in the 150 °C heating test. Summarizing the cycling and the abuse test results, the EC/PC/2MeTHF (15:45:40) ternary mixed systems exhibited the best performance. However, in terms of practical use, cell safety still requires further improvement.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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