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  • Articles: DFG German National Licenses  (13)
  • Polymer and Materials Science  (10)
  • electroretinogram  (3)
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  • Articles: DFG German National Licenses  (13)
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  • 1
    Electronic Resource
    Electronic Resource
    Effect of dopamine and haloperidol on the c-wave and light peak of light-induced retinal responses in chick eye (1987)
    Springer
    Documenta ophthalmologica 65 (1987), S. 87-95 
    Details
    ISSN: 1573-2622
    Keywords: c-wave ; centrifugal fibers ; chick retina ; dopamine ; electroretinogram ; haloperidol ; light peak
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The relation between dopaminergic cells (and centrifugal fibers), the electroretinogram (ERG) c-wave, and the light peak were electrophysiologically investigated by observing the effects of a retrobulbar conduction block and intravitreal injection of either dopamine or haloperidol on these retinal responses. The retrobulbar conduction block (1% lidocaine) caused a decrease in the amplitude of the c-wave and the light peak in newly hatched chicks. Injections (2–20 μl) containing dopamine (0.1–10 mM) or haloperidol (1.3–13 mM) were given intravitreously while the responses were recorded. Although intravitreous injection of saline for control resulted in no observable change in the responses, dopamine selectively augmented the c-wave of ERGs and the light peak, but not the a-, b-, and d-waves. Haloperidol decreased first the light peak and later the c-wave. The augmentation of the retinal responses by dopamine and their reduction by haloperidol was statistically significant. The estimated threshold concentration of dopamine in the vitreous cavity was 1–3.5 μM. Since in many species the interplexiform cells have been found to contain dopamine, we hypothesize that the modulatory effects on the c-wave and the light peak in this preparation may be due to a centrifugal feed-back loop which includes the interplexiform cells to the horizontal and bipolar cells and the horizontal cells to the cones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162724
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Osmotic pressure of the interstitial fluid obtained from neonatal chick eyes and its variation under light and dark adaptation (1985)
    Springer
    Documenta ophthalmologica 61 (1985), S. 79-89 
    Details
    ISSN: 1573-2622
    Keywords: adaptation ; aqueous humor ; electroretinogram ; intraocular fluids ; osmolarity ; vitreous humor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In experiments by Yoneyama et al. (1985) a hypertonic perfusing solution was used to record the c-wave from the isolated chick retina. We investigated whether the chick retina was surrounded by such hypertonic liquids. The following results were found: (1) the osmolarity of the subchoroidal humor was markedly higher than that of fluids from other areas of the eye; (2) the relative difference in osmolarity between both sides of the retina was 110–170 mOsmol in the light-adapted condition, whereas it was about 270 mOsmol in the dark-adapted condition; and (3) in the dark-adapted state the volume of the subchoroidal humor decreased about 40% but increased in osmolarity about 30–40%, whereas osmolarity of the subviteous humor decreased about 15–20 mOsmol. Results suggest the presence of an inward-directed pump mechanism for watersoluble components in the retina in addition to the proposed outward-directed pump mechanism of the pigment epithelium. The inward-directed pump may be more active in the dark-adapted state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00143219
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gamma-aminobutyric acid- and picrotoxin-induced changes in c-wave and light peak of retinal potentials in the chick (1987)
    Springer
    Documenta ophthalmologica 65 (1987), S. 333-342 
    Details
    ISSN: 1573-2622
    Keywords: c-wave ; electroretinogram ; GABA ; light peak ; picrotoxin ; retinal standing potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Retinal potentials were recorded from the eyes of anesthetized and immobilized chicks by a standard direct current method. The amplitude of the electroretinogram (ERG) c-wave was measured 2 and 5 sec after the onset of the light stimulus, as indexes of the fast-rise c-wave (cF-wave) and the slow-rise c-wave (cs-wave), respectively. An intravitreal injection of gamma-aminobutyric acid (GABA) at an estimated intravitreal concentration of 10−9-10−7M resulted in an increase of the amplitude of the cs-wave, a less remarkable change in the a- and cF-waves, and a slight decrease in the b-wave. The light peak of the retinal standing potential increased in amplitude following GABA administration (10−7-10−4M). Following an intravitreal injection of picrotoxin (10−5-10−3M), the polarity of the cs-wave changed from positive to negative and a significant decrease and deformation in the light peak was observed. The amplitude of the a-wave, however, increased in the range of the higher dose, while that of the b- and cf-waves decreased markedly but no polarity reversal of the cF-wave was found. The results may suggest that the GABA-ergic synapse plays a significant role in production of the cs-wave and the light peak, along with that of the pigment epithelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149939
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Positron annihilation in irradiated and unirradiated polyethylenes (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 517-525 
    Details
    ISSN: 0887-6266
    Keywords: positron annihilation in polyethylene, before and after irradiation ; polyethylene, positron annihilation in, effect of radiation on ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Positron lifetimes were measured for four kinds of polyethylene samples and were resolved into four components. The temperature dependence of the two longlived components was examined in detail. In agreement with other results, the longest lived component could be reasonably assigned to ortho-positronium located in amorphous regions. This component was shown to be sensitive to the defects in high-density polyethylene introducted in the course of its production. Both the intensity and the lifetime of the second longest lived component were structure insensitive, i.e., they did not change even on passing through the melting point. This component has been tentatively assigned to a positronium compound state. The effect of gamma-ray irradiation was also examined. Although the intensity (I4) of the longest lived component was reduced by the irradiation, correlation between I4 and the free radical concentration was poor, and the reduction in I4 caused by the irradiation is considered to be due to structure change and not to chemical reasons.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300601
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Novolac epoxy resins and positron annihilation (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 1921-1929 
    Details
    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: Four kinds of epoxy resins: cresol novolac, tris-hydroxyphenylmethane, tetramethylbiphenol, and bisphenol A, were cured with phenol novolac epoxy resins. Characteristics of these epoxy compounds were studied by the positron annihilation lifetime (PAL) technique. Glass transition temperatures, thermal expansion coefficients, and volume of intermolecularspace holes among polymer chains were obtained from the lifetime, τ3, of the long-lived component of ortho-positronium. It was revealed that, at the glass transition temperature, Tg, the volume of the hole created among polymer chains expanded 1.4 times the volume at room temperature. The smaller flexural modulus of tris-hydroxyphenylmethane than that of the other samples was explained by the volume of intermolecular-space holes obtained from τ3. Aging effects were seen in the data of the intensities, I3, of ortho-positronium, which became smaller after heating the samples above Tg. I3 and τ3 were strongly affected by the density of cross-linkings, and their chemical structures. The larger the density of cross-linkings, the smaller I3 and higher Tg were obtained. Epoxy compounds with the higher water-absorption rates had larger intermolecular-space holes. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070491107
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  • 6
    Electronic Resource
    Electronic Resource
    Oxygen dissolution and transport in cobaltporphyrin-bound organophosphazene membranes (1993)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 4 (1993), S. 17-20 
    Details
    ISSN: 1042-7147
    Keywords: Poly(organophosphazene) ; Cobaltporphyrin ; Facilitated transport ; Oxygen-separating membrane ; 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
    Notes: Rubbery poly(organophosphazene)s were synthesized, and were combined with cobaltporphyrin (CoP) which binds molecular oxygen rapidly and reversibly. The apparent oxygen-binding equilibrium constant (Kapp) is in proportion to the physical solubility coefficient of oxygen in the polymer, although the reduced equilibrium and thermodynamic parameters are not dependent on the polymer matrix species. Diffusivity of oxygen via the fixed CoP(DC) is enhanced for poly(organophosphazene) membranes with a larger oxygen diffusion constant. Poly(organophosphazene) membranes with both a large Kapp and DC yield high oxygen permeability.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1993.220040104
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of copolyamide-esters and some aspects involved in their hydrolysis by lipase (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 1701-1711 
    Details
    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: Copolyamide-esters (CPAEs) were synthesized by the amide-ester interchange reaction. The change of intrinsic viscosity during CPAE synthesis was negligible. Polyamide blocks were shortened with increasing reaction time and polyester content. The polymerization degree of nylon 12 blocks on CPAE was smaller than that of nylon 6 blocks. CPAEs were hydrolyzed by Rhizopus delemar lipase. The biodegradability decreased with the shortening of the polyamide blocks and with increasing polyamide content. It was concluded that the amount and distribution of the hydrogen bonds, based on the amide group, in the CPAE chains strongly influenced their biodegradation by this lipase.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240710
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  • 8
    Electronic Resource
    Electronic Resource
    Sputtering of metals with 20 keV O2+: Characteristic etch patterns and sputtered atom yields (1980)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 2 (1980), S. 212-216 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface structures of polycrystalline pure metals bombarded with 20 ke V O+2 were observed by a SEM and their sputtered atom yields obtained by measuring the depth of crater with an interferoscope. The etch patterns produced were classified according to the binding energy of mono-oxide BMO of the target atom M and an oxygen atom; the surface become smooth as the binding energy increased. The sputtered atom yield showed similar periodicity to those obtained by noble gas ion bombardment. It was therefore concluded that the sputtered atom yield was primarily determined by physical collision of atoms in the target material and was not affected very much by the chemical reaction of implanted oxygen atoms.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740020605
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  • 9
    Electronic Resource
    Electronic Resource
    Evaluation of correction accuracy of several schemes for AES matrix effect correctionsPaper presented at ECASIA 89, Antibes, France, 23-27 October 1989. (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 466-472 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A matrix effect correction is required to improve the accuracy of quantitative AES analysis. The correction includes terms involving the atomic density (n), electron back-scattering factor (R) and electron escape depth (L). Many schemes have been proposed by various people for corrections of the R and L terms. However, up to now, there have been no systematic investigations of the correction accuracy of the proposed schemes. We have evaluated the correction accuracy, based on measured intensity data for Au—Cu alloys of different compositions. Comparison was made between the observed intensity ratio K (=Iunk/Istd) and the calculated intensity, ratio K′ (= C(nunk/nstd)(Runk/Rstd)(Lunk/Lstd)), where C and I represent the concentration and intensity, respectively. The superscripts ‘unk’ and ‘std’ denote that the parameters are for unknown and standard specimens, here the pure elements. If the correction works well, the error Er (= K′ — K)/(K) will become smaller. Evaluations were carried out on three schemes for the R correction and on seven schemes for the L correction using the Au 239 eV, Au 2024 eV and Cu 920 eV transitions. The root mean square (RMS) of the calculated errors showed several per cent for the best case and 20-30% for the worst case. The RMS error varied a few per cent between schemes for the R correction but it varied ∼30% for the L correction.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740150805
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  • 10
    Electronic Resource
    Electronic Resource
    The reliability of quantitative analysis with AES (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 140-143 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Japanese VAMAS-SCA working group is composed of 19 institutes. Three kind of Au—Cu alloys (Au 75 at.-%-Cu 25 at.-%, Au 50 at.-%-Cu 50 at.-%, Au 25 at.-%-Cu 75 at.-%) were prepared, and these specimens, pure Au and pure Cu were distributed to the members of the VAMAS-SCA working group. The surface concentrations of these alloys were calculated from the Auger peak amplitudes in two ways. One method used the published relative sensitivity factors, and the other used pure Au and Pure Cu as the standard materials. The mean values of the surface concentrations calculated with the published relative sensitivity factors were almost the same as those calculated with the standard materials. This means that the published relative sensitivity factors are reliable to some extent. The error of the surface concentration calculated with pure Au and pure Cu as the standard materials lay between about 3% and 10%, and that with the relative sensitivity factors lay between about 7% and 20%. The calculated surface concentrations of Au were larger than the bulk concentrations of Au when the matrix effect was neglected.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740160127
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