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  • Cerebral blood flow  (2)
  • sol-gel method  (2)
  • 25.70.Jj  (1)
  • 43.25  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Dynamical Hopf bifurcation in piezoelectric semiconductor resonators (1989)
    Springer
    Applied physics 48 (1989), S. 177-180 
    Details
    ISSN: 1432-0630
    Keywords: 72.20H ; 43.25 ; 72.80E
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Time-dependent Hopf bifurcations in the current-voltage characteristics of piezoelectric semiconductor resonators were investigated experimentally. The switching transition between acoustic bistable states was observed under a quasi-static variation of applied voltage. The peculiar pulse responses of the resonant currents were observed when the rise-time of the pulses exceeded the eigen-period of the system. The existence of a metastable state in the dynamical Hopf bifurcation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01141281
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Haemodynamics and oxygen metabolism in patients after reversible ischaemic attack or minor ischaemic stroke assessed with positron emission tomography (1987)
    Springer
    Neuroradiology 29 (1987), S. 416-421 
    Details
    ISSN: 1432-1920
    Keywords: Reversible ischaemic attacks ; Positron tomography ; Cerebral blood flow ; Cerebral blood volume ; Cerebral oxygen metabolism ; Carotid stenosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Regional cerebral blood flow (CBF), blood volume (CBV) and oxygen metabolic rate (CMRO2) were evaluated and compared among normals, patients with recent reversible ischaemic attacks (RIAs) and patients with chronic minor infarction using positron emission tomography. Average CBF together with CMRO2 significantly decreased in the infarction group in the middle cerebral artery territory of the affected hemisphere while the mean values for RIAs were intermediate between the other two groups. CBV also reduced, however it was more preserved compared to flow as seen in decreased CBF/CBV values. Significant interhemispheric difference was found in CBF/CBV ratio, but it did not clearly correlate with OEF changes. Higher OEF was noted only in the restricted brain regions of RIAs where CBF showed large hemispheric asymmetry. However, in other regions, the coupled decline of blood flow and metabolism was found which suggests tissue damage or neuronal cell loss in the brain with previous RIA symptoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341736
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Positron CT imaging of an impending stroke (1988)
    Springer
    Neuroradiology 30 (1988), S. 276-279 
    Details
    ISSN: 1432-1920
    Keywords: Transient ischemic attack ; Cerebral infarction ; Cerebral blood flow ; Positron tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We present PET findings of a case of a transient ischemic attack which later progressed to cerebral infarction. Cerebral blood flow at the stroke focus in the right parietal cortex measured after a TIA attack and before stroke was as low as 24 ml/100 g/min with some increase in oxygen extraction fraction and blood volume. The condition was compatible with “misery perfusion”. This case may be an example suggestive that the “misery perfusion sign” is a warning of impending stroke and its poor prognosis if left without appropriate treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341844
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Sol-Gel Preparation of Silica Films with Controlled Surface Morphology and Their Application to a Low Reflective Glass (1999)
    Springer
    Journal of sol gel science and technology 14 (1999), S. 175-186 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel method ; silica film ; surface morphology ; porous ; low reflective glass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silica coating films with various surface morphologies, such as flat, porous (with deep pores), concave-convex (with hills and valleys), and convex (with hills on flat plane) structure were prepared from a mixture of two kinds of sols derived from polymerized tetraethoxy-silane (TEOS) and methyltriethoxysilane (MTES). Different surface morphologies were obtained by varying the molar ratio r = MTES/TEOS of the coating solution. The surface was flat for r less than 2.5, porous for 2.5 ≤ r 〈 5, concave-convex for 5 ≤ r 〈 7.5, convex for 7.5 ≤ r 〈 13, and again flat for r larger than 13. For 2.5 ≤ r 〈 5, the apparent refractive index of the silica film with porous morphology was decreased to 1.23 by selecting the solvent and by controlling the relative humidity of the coating atmosphere and the heat treatment temperature. Coating of glass with silica films of low refractive index of 1.23 led to the low reflective glasses with visible light reflectance Rvis of less than 0.2%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008738117124
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  • 5
    Electronic Resource
    Electronic Resource
    Competition between the fusion-fission and deep-inelastic orbiting mechanisms in the35Cl +12C reaction (1992)
    Springer
    The European physical journal 343 (1992), S. 309-323 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.Jj ; 25.70.Lm ; 25.85.Ge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The binary decay properties of the47V nucleus, produced in the35Cl +12C reaction, have been investigated at the35Cl bombarding energiesE lab = 180 and 200 MeV by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and a characteristic 1/sin(θ cm) angular distribution. The elemental distribution of the fully-damped products is asymmetric, similar to what has previously been observed in the decay of the56Ni nucleus. Comparison with theoretical model predictions suggests the occurrence of a fusion-fission rather than orbiting process. Moreover the calculations performed using the Extended Hauser-Feshbach Method reproduce well the experimental fission yields. A general discussion of orbiting and fusionfission experimental data of light heavy-ion systems is presented in the framework of the calculated number of available open channels for these systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01291530
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation and properties of polyborosiloxanes as precursors for borosilicate formation of SiO2-B2O3 gel fibers and oxides by the sol-gel method using tetraacetoxysilane and boron tri-n-butoxide (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1049-1056 
    Details
    ISSN: 0887-624X
    Keywords: tetraacetoxysilane ; boron tri-n-butoxide ; sol-gel method ; condensation ; SiO2 - B2O3 gel fibers ; borosilicates ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of SiO2-B2O3 gel fibers and oxides was investigated by the sol-gel method using tetraacetoxysilane (TAS) and boron tri-n-butoxide (BTB). Low molecular weight borosiloxanes (BS) were formed by the reaction of TAS with BTB in THF. Partial alkoxylation and hydrolysis of BS followed by further condensation of the resulting polymer (PBS) solutions led to the formation of highly polymerized polyborosiloxanes (HPBS) with good spinnability. Gel fibers were obtained by dry spinning of HPBS. The compositions of PBS and gels were not consistent with that in feed. Heat treatment of the gels, however, provided SiO2-B2O3 oxides with compositions almost compatible with those of the gels. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320606
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