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  • 1
    Electronic Resource
    Electronic Resource
    Morphological features of blown high-density polyethylene films (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1717-1729 
    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: The blown films of high-density polyethylenes with unimodal and bimodal molecular weight distribution were prepared under several processing conditions, and their morphologies were extensively characterized. The high molecular weight tail (MW 〉 ∼ 106) of the molecular weight distribution seems to play a critical role on the morphology of blown highdensity polyethylene films irrespective of the molecular weight distribution mode of the resins. As the content of high molecular weight species increased, the tendency for high stress-crystallization increased and the network structure of lamellar stacks was better developed. The intercrystalline connectivity along the normal direction of lamellar stacks was higher than that along the transverse direction of lamellar stacks. © 1996 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of preparation process of PMDA-ODA-DR1 polyimide on its second harmonic generation characteristics (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 1625-1634 
    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: In situ second harmonic generation (SHG) observation of PMDA-ODA-DR1 polyimide films prepared by different preparative procedures were studied to understand the effects of the residual acid and the imidization byproduct and the extent of imidization on the SHG characteristics of the PMDA-ODA-DR1 polyimides. PMDA-ODA-DR1 polyimides with or without removal of salt were also investigated to study the influence of remaining triethyl hydrogen ammonium chloride salt on the SHG characteristics and reliability of the polymers. A blue shift in the UV/vis spectrum during poling was observed for the low temperature-baked film, but did not occur for the high-temperature-baked film. Both high temperature imidization and removal of the byproduct organic salt did not only improve the poling efficiency of PMDA-ODA-DR1 polyimide as a SHG material, but also slowed down the relaxation of the film and made the film more reliable. © 1995 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070561213
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  • 3
    Electronic Resource
    Electronic Resource
    Short chain branching distribution and thermal behavior of high density polyethylene (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 2469-2479 
    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: High-density polyethylenes with unimodal and bimodal molecular weight distribution have been fractionated according to crystallizability using preparative temperature rising elution fractionation. The molecular structure and thermal properties of the fractions with their whole polymers have been characterized. The average short chain branching content of the fractions obtained ranged from 0 to 8 branches per 1000 carbon atoms while that of the whole polymers is about 2 branches per 1000 carbon atoms. The bimodal resins have a slightly higher frequency of short chain branch in higher molecular weight species than in those of the unimodal resins. The short chain branching distribution as well as the low molecular weight species in the fractions seem to be important parameters to determine thermal behavior of the fractions. The fractions with the short chain branching content above 3 branches per 1000 carbon atoms showed a significantly different thermal behavior from those with less than 3 branches per 1000 carbon atoms. © 1996 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of arsenic vapour species on electrical and optical properties of GaAs grown by molecular beam epitaxy (1982)
    Springer
    Applied physics 28 (1982), S. 167-173 
    Details
    ISSN: 1432-0630
    Keywords: 68.55.+ b ; 71.55.-i ; 72.20.-i ; 78.55.-m
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Hall effect, DLTS and low-temperature photoluminescence measurements were used to study the effect of dimeric (As2) vs tetrameric (As4) vapour species on the electrical and optical properties of nominally undoped and of Ge-doped GaAs layers grown by molecular beam epitaxy (MBE). The arsenic molecular beam was generated from separate As2 and As4 sources, respectively, and from a single source providing an adjustable As2/As4 flux ratio. The occurence of the previously described defect related bound exciton lines in the luminescence spectra at 1.504–1.511 eV was found to be directly correlated with the presence of three deep states (M1, M3, M4) which are characteristic of MBE grown GaAs. The intensity of the extra luminescence lines and simultaneously the concentration of the deep electron traps can be reduced substantially simply by decreasing the As4/As2 flux ratio. The incorporation of defect related centers as well as of amphoteric dopants like Ge strongly depends on the surface chemistry involved. Therefore, a considerably lower autocompensation ratio in Ge-dopedn-GaAs is obtained with As2 molecular beam species which provide a higher steady-state arsenic surface population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617982
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  • 5
    Electronic Resource
    Electronic Resource
    Photoluminescence of Al x Ga1−x As/GaAs quantum well heterostructures grown by molecular beam epitaxy (1984)
    Springer
    Applied physics 33 (1984), S. 9-17 
    Details
    ISSN: 1432-0630
    Keywords: 81.15.-z ; 78.55.-m ; 78.20.-e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Nominally undoped AlxGa1−xAs grown by molecular beam epitaxy from As4 species at elevated substrate temperatures of 670°C exhibits well-resolved excitonic fine structure in the low-temperature photoluminescence spectra, if the effective As-to-(Al+Ga) flux ratio on the growth surface is kept within a rather narrow range of clearly As-stabilized conditions. In contrast to previous results on AlxGa1−xAs of composition 0.15〈x〈0.25, the prominent carbon-related recombination at ∼23 meV below the bound exciton line was foundnot to shift in energy by changing the excitation intensity. This implies a simple freeelectron carbon-acceptor recombination mechanism for the line without any participation of a donor. In AlxGa1−xAs of composition close to the direct-to-indirect cross-over point, two distinct LO-phonons separated by 34 and 48 meV from the (D 0,C 0) peak position at x=0.43 were observed which were before only detectable by Raman scattering experiments. The intensity of the carbon-impurity related luminescence lines in bulk-type AlxGa1−xAs and GaAs layers was found to be strongly reduced, as compared to the excitonic recombination lines, if the respective active layer was covered by a very thin confinement layer of either GaAs on top of AlxGa1−xAs or vice versa grown in the same growth cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197079
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  • 6
    Electronic Resource
    Electronic Resource
    Blends of chlorinated isotactic polypropylene with poly(ethylene-co-vinyl acetate) IIPart I, cf.1.. Phase studies of the miscible blends (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 165 (1989), S. 89-95 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Messungen von Tg, Tm und Tc (Trübungspunkt) wurden Phasendiagramme der vier verträglichen Polymermischungen von chlorierten isotaktischen Polypropylenen (Chlorgehalt 39,2 (CPP-40) und 49,8 Gew.-% (CPP-50)) mit Poly(ethylen-co-vinylacetat)en (Vinylacetatgehalt 40 (EVA-40) und 45 Gew.-% (EVA-45)) untersucht. Von den vier Mischungspaaren war die Mischung von CPP-50 mit EVA-40 am besten verträglich.
    Notes: By measuring Tg, Tm and Tc (cloud point) phase diagrams for the four miscible blends of chlorinated isotactic polypropylenes (chlorine content 39.2 (CPP-40) and 49.8 wt.-% (CP-50)) with Poly(ethylene-co-vinyl acetate)s (vinyl acetate contents 40 (EVA-40) and 45 wt.-% (EVA-45)) were investigated. The blend of CPP-50 with EVA-40 was the most compatible of the four blend pairs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051650108
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  • 7
    Electronic Resource
    Electronic Resource
    Modifizierung von polymeroberflächen zur erhöhung der zelladhäusionVortrag anläßlich der Tagung der Fachgruppe “Makromolekulare Chemie” der Gesellschaft Deutscher Chemiker über “Polymere und biologische Funktionen” in Bad Nauheim am 18. und 19. April 1988 (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 166 (1989), S. 179-189 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: After implantation a stable bond between the implant and the surrounding tissue is required. Therefore a high cell adhesion of the polymer surface of the implant must be achieved. Depending on the treatment time of a polydimethylsiloxane foil with oxygen plasma, the cell adhesion can be improved. FT-IR spectroscopy and ESCA analysis were used to characterize the surface modification. The cell spreading and cell adhesion increase with increasing hydrophilic character of the polymer surface after plasma treatment. A pronounced correlation was found between the efficiency of DNA and protein content, characterizing cell growth, and the spreading of the cells.Polydimethylsiloxane, Glow-Discharge, Surface Modification, Cell Adhesion, Cell Proliferation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051660113
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation and uranyl ion adsorptivity of macroreticular chelating resins containing phosphono groups (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 117-129 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Makroretikulare Copolymerperlen wurden durch Suspensionspolymerisation von Styrol, Bis(2-chlorethyl)vinylphosphonat (CEVP) und Divinylbenzol (DVB) in Gegenwart von Toluol als Verdünnungsmittel hergestellt. Die auf der Perlenoberfläche vorhandenen 2-Chlorethylphosphonat-Gruppen wurden durch Hydrolyse mit verdünnter Salpetersäure in Phosphon-Gruppen transformiert. Für die Einführung zusätzlicher Phosphon-Gruppen wurden die Copolymeren in Gegenwart von Aluminiumchlorid-Katalysator mit Phosphortrichlorid phosphoryliert, und die dabei entstandenen Dichlorphosphingruppen wurden mit verdünnter Salpetersäure verseift und oxidiert. Die Untersuchungen zur Chelatbildung der Copolymeren mit Metallionen zeigten, daß sie ein hohes Adsorptionsvermögen für Uranylionen und gute Stabilität gegen Chemikalien wie Säuren und Alkalien aufweisen. Es wurde auch gefunden, daß die Phosphongruppen enthaltenden Copolymeren recht effektive Adsorbentien für eine Vielzahl von Schwermetalionen wie Pb2+, Hg2+, Cd2+ und Cu2+ sind.
    Notes: Macroreticular copolymer beads were prepared by suspension polymerization of styrene, bis(2-chloroethyl) vinyl phosphonate (CEVP) and divinylbenzene (DVB) in the presence of toluene as diluent. The bis(2-chloroethyl) phosphonate groups on the bead surface were converted into phosphono groups by hydrolysis with dilute nitric acid. For the additional enrichment of phosphono groups, the copolymers were phosphorylated at the phenyl rings with phosphorus trichloride in the presence of aluminum chloride and hydrolyzed and oxidized with dilute nitrics acid. The investigations on metal ion chelation characteristics of the bead-type copolymers revealed that they have very high adsorptivity toward uranyl ions and good chemical resistance under acidic and alkaline media. It was also found that the phosphono group-containing copolymer beads are effective adsorbents for other heavy metal ions such as Pb2+, Hg2+, Cd2+, and Cu2+.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970110
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  • 9
    Electronic Resource
    Electronic Resource
    Circular dichroism and conformational analysis of the membrane-modifying peptide -N-t-Boc-(Aib-L-Ala)5-Gly-Ala-Aib-Pro-Ala-Aib-Aib-Glu-(OBzl)-Gln-OMe with respect to alamethicin (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 203-214 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational analysis of the CD spectrum is reported for the synthetic and membrane-modifying nonadecapeptide analog of alamethicin N-t-Boc-(Aib-L-Ala)5-Gly-Ala-Aib-Pro-Ala-Aib-Aib-Glu(OBzl)- Gln-OMe. The CD data are evaluated according to three different methods and are discussed with respect to those obtained from natural alamethicin and suitable models such as N-t-Boc-(Aib-L-Ala)7-OPOE, fragments of the synthetic nonadecapeptide, and the hexadecapeptide N-t-Boc-(Aib-L-Ala)5-Pro-Ala-Aib-Aib-Glu(OBzl)-Gln-OMe. The synthetic nonadecapeptide with the longer helical region exhibits membrane activities comparable to those of alamethicin, whereas the hexadecapeptide with the shorter helix is inactive.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190114
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  • 10
    Electronic Resource
    Electronic Resource
    Crystal structure of Boc-Leu-Aib-Pro-Val-Aib-Aib-Glu(OBzl)-Gln-Phl × H2O, the C-terminal nonapeptide of the voltage-dependent ionophore alamethicin (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 979-999 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Boc-L-Leu-Aib-Pro-Val-Aib-Aib-Glu(OBzl)-Gln-Phl (Boc = t-butyloxycarbonyl, Aib = α-aminoisobutyric acid, Bzl = benzyl, Phl = phenylalaninol), C59H90N10O14, the protected C-terminal nonapeptide with the sequence 12-20 of alamethicin, crystallizes in the orthorhombic space group P212121 with a = 15.666, b = 16.192, c = 26.876 Å, and Z = 4. The molecular conformation is right-handed helical with three α-(5 → 1 hydrogen bonds) and three β-turns (4 → 1 hydrogen bonds). All but two of the hydrogen bonds are significantly longer than the usual value and show bifurcation to some extent. The α/310r-helical nonapeptide molecules are arranged head-to-tail along the a direction. The resulting linear antiparallel chains are linked by a weak intermolecular hydrogen bridge, thus forming a two-dimensional layer structure in the ab plane. The conformation of this nonapeptide is almost identical with that of the corresponding C-terminal part found by x-ray crystallography of the eicosapeptide alamethicin.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360240606
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