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  • Articles  (16)
  • Articles: DFG German National Licenses  (16)
  • Springer  (16)
  • 1995-1999  (16)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Der Onkologe 3 (1997), S. 99-104 
    ISSN: 1433-0415
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4846
    Keywords: electrochromism ; coating ; nanoparticle ; sol-gel material ; WO3 ; Nb2O5 ; TiO2 ; CeO2 ; Fe2O3 ; mixed compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electrochromism is defined as the persistent but reversible optical change (usually transmission) produced electrochemically. The preparation by the sol-gel process of thin films made of amorphous or crystalline nanoparticles of WO3, V2O5, Nb2O5, TiO2, CeO2, Fe2O3 and mixed compounds such as WO3-TiO2, CeO2-TiO2, CeO2-SnO2, have opened remarkable new opportunities for obtaining electrochromic layers exhibiting large optical transmission variation in the UV, visible or infrared range and acceptable kinetics under H+ or Li+ insertion. In this paper we give an overview of what has been recently achieved in this field, with emphasis for cathodic electrochromic coatings of Nb2O5 and TiO2 composition. Finally we stress the future developments in this fast growing field.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4846
    Keywords: sol-gel ; Nb2O5 ; film ; photoconductivity ; photoelectrochemistry ; semiconductor ; solar cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Structural, optical, electro and photoelectrochemical properties of amorphous and crystalline sol-gel Nb2O5 coatings have been determined. The coatings are n-type semiconductor with indirect allowed transition and present an overall low quantum efficiency (φ 〈 4%) for UV light to electric conversion. The photoconducting behavior of the coatings is discussed within the framework of the Gärtner and Södergren models. Improvement can be foreseen if Nb2O5 coatings can be made of 10–20 nm size nanoparticles.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-4846
    Keywords: ormocer ; coatings ; chemical protection ; stainless steel ; PMMA-ZrO2 ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chemical protection of 316 L stainless steel coated with ORMOCER coatings of polymethylmethacrylate (PMMA) and ZrO2 has been verified. The coatings were dip-coated on the substrates from sols prepared by mixing zirconium propoxide (ZrOC3H7)4, isopropanol (C3H7OH), glacial acetic acid (CH3COOH), polymethylmethacrylate and water under application of ultrasounds. The films were heat treated between 40 and 300°C in air up to 20 h. Their morphology was studied by electron scanning microscopy (SEM). Their anticorrosion behavior was analysed in 0.5M-H2SO4 solutions through potentiodynamic polarization curves at room temperature. The influence of the sol preparation, coating composition as well as of the duration and temperature of heat treatments on the corrosion parameters is reported. The films act as geometric blocking layers against the corrosive media and increase the lifetime of the substrate up to a factor 30.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-4846
    Keywords: electrochromism ; coating ; nanoparticle ; sol-gel material ; WO3 ; Nb2O5 ; TiO2 ; CeO2 ; Fe2O3 ; mixed compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electrochromism is defined as the persistent but reversible optical change (usually transmission) produced electrochemically. The preparation by the sol-gel process of thin films made of amorphous or crystalline nanoparticles of WO3, V2O5, Nb2O5, TiO2, CeO2, Fe2O3 and mixed compounds such as WO3−TiO2, CeO2−TiO2, CeO2−SnO2, have opened remarkable new opportunities for obtaining electrochromic layers exhibiting large optical transmission variation in the UV, visible or infrared range and acceptable kinetics under H+ or Li+ insertion. In this paper we give an overview of what has been recently achieved in this field, with emphasis for cathodic electrochromic coatings of Nb2O5 and TiO2 composition. Finally we stress the future developments in this fast growing field.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-4846
    Keywords: hybrid materials ; ORMOLYTES ; ionic conductivity ; nuclear magnetic resonance (NMR) ; polymers ; SiO2-PEG, SiO2-PPG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two families of hybrid organic-inorganic composites exhibiting Li+ ionic conduction (ORMOLYTES) have been prepared by the sol-gel process. The first family, prepared from a mixture of 3-isocyanatopropyltriethoxysilane, O,O′ Bis (2-aminopropyl)-polyethyleneglycol (or O,O′ Bis (2-aminopropyl)-polypropyleneglycol) and lithium salt, presents chemical bonds between the organic and the inorganic phase and an ionic conductivity σ higher than 10−4 S m−1 at room temperature. Their properties have been related to their structure using liquid state NMR measurements of7Li between −100°C and +100°C and the DMTA technique. In the second family, prepared by ultrasonic method from a mixture of tetraethoxysilane (TEOS), polyethyleneglycol (PEG) and lithium salt, the organic and inorganic phases are not chemically bonded. Ionic conductivity σ has been studied as a function of the polymer chain length and concentration. Values of σ up to 10−2S m−1 at room temperature have been obtained (with a silica-PEG300 system, PEG/TEOS=40% in weight). Again, structure was investigated by liquid state7Li NMR measurements.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-4846
    Keywords: ormocer ; coatings ; chemical protection ; stainless steel ; PMMA-ZrO2 ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chemical protection of 316 L stainless steel coated with ORMOCER coatings of polymethylmethacrylate (PMMA) and ZrO2 has been verified. The coatings were dip-coated on the substrates from sols prepared by mixing zirconium propoxide (ZrOC3H7)4, isopropanol (C3H7OH), glacial acetic acid (CH3COOH), polymethylmethacrylate and water under application of ultrasounds. The films were heat treated between 40 and 300°C in air up to 20 h. Their morphology was studied by electron scanning microscopy (SEM). Their anticorrosion behavior was analysed in 0.5M-H2SO4 solutions through potentiodynamic polarization curves at room temperature.The influence of the sol preparation, coating composition as well as of the duration and temperature of heat treatments on the corrosion parameters is reported. The films act as geometric blocking layers against the corrosive media and increase the lifetime of the substrate up to a factor 30.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-4846
    Keywords: sol-gel ; Nb2O5 ; film ; photoconductivity ; photoelectrochemistry ; semiconductor ; solar cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Structural, optical, electro and photoelectrochemical properties of amorphous and crystalline sol-gel Nb2O5 coatings have been determined. The coatings aren-type semiconductor with indirect allowed transition and present an overall low quantum efficiency (ϕ〈4%) for UV light to electric conversion. The photoconducting behavior of the coatings is discussed within the framework of the Gärtner and Södergren models. Improvement can be foreseen if Nb2O5 coatings can be made of 10–20 nm size nanoparticles.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4846
    Keywords: hybrid materials ; ORMOLYTES ; ionic conductivity ; nuclear magnetic resonance (NMR) ; polymers ; SiO2-PEG ; SiO2-PPG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two families of hybrid organic-inorganic composites exhibiting Li+ ionic conduction (ORMOLYTES) have been prepared by the sol-gel process. The first family, prepared from a mixture of 3-isocyanatopropyltriethoxysilane, O,O′ Bis (2-aminopropyl)-polyethyleneglycol (or O,O′ Bis (2-aminopropyl)-polypropyleneglycol) and lithium salt, presents chemical bonds between the organic and the inorganic phase and an ionic conductivity σ higher than 10-4 S m-1 at room temperature. Their properties have been related to their structure using liquid state NMR measurements of 7Li between -100°C and +100°C and the DMTA technique. In the second family, prepared by ultrasonic method from a mixture of tetraethoxysilane (TEOS), polyethyleneglycol (PEG) and lithium salt, the organic and inorganic phases are not chemically bonded. Ionic conductivity σ has been studied as a function of the polymer chain length and concentration. Values of σ up to 10-2 S m-1 at room temperature have been obtained (with a silica-PEG300 system, PEG/TEOS = 40% in weight). Again, structure was investigated by liquid state 7Li NMR measurements.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1912
    Keywords: Key words P2X Purinoceptor ; βγ-Methylene-L-ATP ; Rat vagus nerve ; Nodose ganglion neurones ; Rat vas deferens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effects of the putative selective P2X purinoceptor agonist, β,γ-methylene-L-adenosine 5′-triphosphate (βγme-L-ATP), were determined at rat neuronal and smooth muscle P2X purinoceptors. βγMe-L-ATP had no effect on the extracellularly recorded membrane potential of the rat isolated vagus nerve preparation at concentrations up to 300 μM. In contrast, the archetypal P2X purinoceptor agonist, α,β-methylene ATP (αβmeATP; 1–100 μM), produced concentration-related depolarisation responses with a mean EC50 value of 10.8 μM. The depolarising effects of αβmeATP were not attenuated by βγme-L-ATP (100 μM). In voltage clamp experiments on single nodose ganglion neurones, ATP (100 μM), but not βγme-L-ATP (1–300 μM), evoked rapid (〈20 ms onset) inward currents when applied using a concentration-clamp method. In receptor binding studies to rat brain membranes, βγme-D-ATP and αβmeATP competed with high affinity for [3H]αβmeATP binding sites, with mean pIC50 values of 7.7 and 8.3, respectively. However, βγme-L-ATP possessed low affinity for these sites and competed only at concentrations in excess of 10 μM (mean pIC50 value 4.1). In prostatic segments of the rat vas deferens, βγme-L-ATP (1–100 μM) and αβmeATP (0.3–100 μM) each produced concentration-related contractile responses with mean EC50 values of 17.1 and 3.6 μM, respectively. βγMe-L-ATP (1–10 μM) evoked fast inward currents in freshly dispersed vas deferens smooth muscle cells, indicative of an action at ligand-gated ion channels. Binding sites in vas deferens membranes labelled using 1 nM [3H]αβmeATP exhibited high affinity for βγme-L-ATP, αβmeATP and βγme-D-ATP with mean pIC50 values of 7.7, 8.4 and 7.3, respectively. These results indicate that βγme-L-ATP exhibits neither agonist nor antagonist properties at P2X purinoceptors on rat vagal neurones and possesses only very low affinity for [3H]αβmeATP binding sites in rat brain. In contrast, βγme-L-ATP is a potent, high affinity agonist at smooth muscle P2X purinoceptors of the rat vas deferens. This selective agonist action of βγme-L-ATP suggests that P2X purinoceptors in smooth muscle and neurones are different and represent distinct P2X purinoceptor subtypes.
    Type of Medium: Electronic Resource
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