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  • Articles  (7)
  • Articles: DFG German National Licenses  (7)
  • Polymer and Materials Science  (3)
  • Nodose ganglion neurones  (2)
  • chemical protection  (2)
  • 1995-1999  (7)
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  • Articles  (7)
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  • Articles: DFG German National Licenses  (7)
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  • 1
    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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  • 2
    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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  • 3
    ISSN: 0887-6266
    Keywords: polyethylene ; poly(butylene terephthalate) ; blend ; rheology ; Palierne's model ; morphology ; differential scanning calorimetry ; crystallization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crystallization at high supercooling of polybutylene terephthalate (PBT) droplets dispersed in a molten polyethylene (PE) matrix was investigated through rheological and DSC experiments. The Palierne's emulsion model was used as a theoretical framework for studying the viscoelastic behavior of the blends in different ranges of temperature: on the one hand, when the two polymers are molten (T 〉 225°C) and on the other hand, when PBT droplets are at high supercooling in the molten PE matrix (130°C 〈 T 〈 205°C). From rheological experimental evidences it was shown that molten and solidified droplets coexist at high supercooling. The Palierne's model was then successfully adapted to take into account the three phases (molten PE, molten PBT droplets, and solidified PBT droplets). The evolution of the behavior with the temperature is consistent with the growing amount of crystallized droplets. Moreover, a calculation taking into account the droplets size distribution and the number of nuclei is introduced to explain the crystallization behavior of three different blend ratios.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2573-2585, 1998
    Additional Material: 9 Ill.
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  • 4
    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.
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  • 5
    ISSN: 1432-1912
    Keywords: 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]Lx βmeATP 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 ββ γme-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.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1393-1399 
    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: Thermorheological properties of an incompatible polymer blend of polypropylene inclusions dispersed in a ethylene copolymer matrix were discussed from the emulsion model developed by Palierne. Due to the different rheological behaviors with temperature of the two phases, such a system proved to be a judicious blend in order to consider the special cases of the model applications: (1) the two phases are viscoelastic liquids, (2) the dispersed phase is a solid elastic assimilated to rigid spheres in comparison with viscoelastic liquid behavior of the matrix, and (3) the two phases are elastic solids. At low frequencies, the rheological behavior of the blend was not correctly predicted by the model. So interactions other than hydrodynamics can exist in the intrafacial region, and physical entanglements between the chains of the two constituents leading to topological interactions may be assumed at the interphase. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 7
    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: A poly(vinyl chloride) (PVC)/poly(methyl methacrylate) (PMMA) (80/20 w/w) polymer blend was studied by mechanical spectroscopy. Two relaxations can be distinguished: in the glassy state, a very large secondary relaxation in the range of 100 K to 325 K which results from the combination of secondary relaxations of PVC and PMMA; and only one main relaxation at 364 K associated to the glass rubber transition. The relaxation spectrum in the range of the β relaxation has been described by a relaxation time distribution function based upon a Gaussian function and a series-parallel model. The α relaxation was studied by means of a theoretical approach for the nonelastic deformation of polymers. We found that the miscibility of this blend appears to be a function of the observation scale: the PVC/PMMA blend is heterogeneous at the scale of molecular movements involved for the β relaxation process but homogeneous at the scale of the chain segments responsible for the α relaxation dynamics. © 1996 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
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