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  • 1
    Electronic Resource
    Electronic Resource
    Intermediacy of uro'gen III and of a heptacarboxylic uro'gen in corrinoid biosynthesis (1975)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 97 (1975), S. 2548-2550 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00842a045
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  • 2
    Electronic Resource
    Electronic Resource
    Biosynthesis of uroporphyrinogen III from porphobilinogen. Resolution of the enigmatic "switch" mechanism (1976)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 98 (1976), S. 1589-1591 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00422a057
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of marginal sealing ability of new generation bonding systems (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 25 (1998), S. 0 
    Details
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of this in vitro study was to evaluate the enamel and dentine marginal sealing ability of four new generation composite bonding systems. Two Class V preparations, which were solely in enamel and dentine/cementum, were made on the buccal surfaces of 96 freshly extracted molar teeth. The teeth were randomly divided into four groups of 24 and restored with composite resin (Silux Plus®) utilizing the following bonding systems: Scotchbond Multi-purpose® (SB), Fuji Bond LC® (FB), Prime & Bond 2·0® (PB) and Bisco One-step® (BC). The restorations were finished immediately after photo-polymerization and stored in saline at 37 °C for 1 week. Half of the specimens in each group were then thermally stressed for 500 cycles. All restorations were then subjected to dye penetration testing, sectioned and scored. Results revealed no statistically significant difference (P 〈 0·05) in dye penetration scores for the different bonding systems with the exception of leakage at the dentine margins of thermally stressed specimens where FB exhibited significantly better sealing ability compared with the other bonding systems and BC exhibited significantly less leakage than PB. The marginal seal of ‘one-step’ (PB and BC) and resin-modified glass–ionomer (FB) bonding systems appear to be as effective as ‘two step’ systems like SB. Thermal stresses had some influence on marginal seal but this was both product and tissue specific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2842.1998.00296.x
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  • 4
    Electronic Resource
    Electronic Resource
    Study of SmTM7.3 microstructure by a simplified method and its correlation to properties (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3772-3774 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By using a newly developed potentiostatic etching technique, the microstructural evolution of an SmTM7.3 (TM=Co/Fe/Cu/Zr) alloy during different stages of heat treatment has been easily and successfully observed under a conventional scanning electron microscope (SEM). Specimens up to several centimeters were examined, with their features being statistically measured. It is found that the cell structure has been well developed with a median size of 110 nm after aging 2 h at 1123 K, while the intrinsic coercivity (iHc) was as low as 2 kOe. The cell size grows slowly during subsequent heat treatment to a median size of 220 nm after the whole treatment. For aging at 1123 K for 4 h, iHc value is around 4 kOe, and the platelet phase appears. After aging at 1123 K for 8 h, a large zonal phase and grain boundary phase are visible. It is thus believed that the zonal phase appears after aging for a time period between 4 and 8 h, corresponding to the iHc of 600 kA/m (7.5 kOe). No new microconstituent appears after the isothermal aging for more than 8 h, however growth proceeds. After the whole heat treatment cycle, iHc is much greater than 2400 kA/m (30 kOe), with the zonal phase ranging in size from 300 to 900 nm (in width, averaged 400 nm), 1 to 5 μm in length (averaged 3.6 μm), and 1 to 6 μm in separation (averaged 3.5 μm). The zonal and the grain boundary phases are thus concluded to be the dominating structure for the extremely high coercivity of this alloy. A model is proposed to explain the etching sequence of the microconstituents during the potentiostatic etching, and is successful to explain the resultant microstructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338638
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of polyamide-imide by blocked-methylene diisocyanates (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1711-1717 
    Details
    ISSN: 0887-624X
    Keywords: poly(amide-imide) ; p-chlorophenol blocked diisocyanates ; trimellitic anhydride ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of polyamide-imide (PAI) can be performed by the reaction of p-chlorophenol-(PCP) blocked 4,4′-diphenyl methane diisocyanates (BMDI) with trimellitic anhydride (TMA) using a two-stage heating. At 80°C the polyimide oligomers were first formed and the high molecular weight PAI can not be available until the temperature was increased to 120°C and stayed for 3 h, during which the amide groups were formed and the molecular weight was increased. The molecular weights of the synthesized PAIs on various conditions were analyzed by measuring the intrinsic viscosity, amide/imide ratio from IR spectra, and average chain length from GPC. The best reaction conditions for obtaining a high molecular weight PAI by the solution polymerization are: (a) using N-methyl pyrollidone (NMP) as solvent, (b) adding more BMDI/TMA ratio, and (c) adding tert-n-butyl amine as the catalyst for the dissociation of blocked MDI and controlling the catalyst concentration at 0.162M. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1711-1717, 1997
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetic studies of polyamide-imide synthesis (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1703-1710 
    Details
    ISSN: 0887-624X
    Keywords: polyamide-imide ; kinetic study ; p-chlorophenol blocked isocyanates ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To understand the kinetic of synthesis of polyamide-imide (PAI) via p-chlorophenol-(PCP) blocked 4,4′-diphenyl methane diisocyanate (MDI) with trimellitic anhydride (TMA), a series of reactions of blocked MDI with excess phthalic anhydride (PA) and benzoic acid are designed. PCP-blocked phenyl isocyanate (BPI) which also released isocyanate at higher temperatures was used as a model compound for BMDI. The dissociation constants of BPI and BMDI in the presence of excess PA or BA was measured by collecting the evolved CO2. The effect of the catalyst concentration and temperatures were combined by a Hostettler equation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1703-1710, 1997
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Miscibility studies of poly(3-octylthiophene)/poly(ethylene-co-vinylacetate) blends with a solvatochromatic shift in the solid state (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 537-545 
    Details
    ISSN: 0887-6266
    Keywords: miscibility ; P3OT/EVA blends ; solvatochromatic shift ; solid state ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mixing of electrically conducting polymers in the undoped state with flexible polymers has been limited due to the stiffness of the delocalized coplanar backbone. The substitution with alkyl side chains has resulted in the distortion of the aromatic rings in the backbone with an increase of the flexibility. The alkyl substituents also prevent the thiophene back-bones from packing together, thus making blending with other polymers promising. We have investigated the phase behavior of poly(3-octylthiophene) (P3OT) with a flexible polymer, poly(ethylene-co-vinylacetate) (vinylacetate composition 20%, EVA20), and defined a miscibility window based on melting point data, on cloud point measurements, and on analysis by optical microscopy. The miscible region has been studied by UV-VIS and CPMAS NMR spectroscopies. A UV absorption in the visible region originates from a π-π * transition in the delocalized structure of P3OT, and a change in the length of the conjugated segment in the backbone results in a shift of this absorption. A gradual solvatochromatic shift of P3OT in the solid state with dilution was observed in the miscible region. T1 relaxation times for the methylene carbons in solid state show a gradual change in the relaxation process as a function of composition. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330402
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  • 8
    Electronic Resource
    Electronic Resource
    2-Hydroxyethyl methacrylate-terminated polyurethane/polyurethane interpenetrating polymer networks (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 34 (1997), S. 261-268 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interpenetrating polymer networks (IPNs) of polyurethane (PU) and 2-hydroxyethyl methacrylate (MEHA)-terminated polyurethane (HPU) were prepared by solution polymerization. PU prepolymer was synthesized from 4,4-diphenyl methane diisocyanate (MDI) and poly(propylene oxide) glycol (PPG). HPU prepolymer was synthesized from MDI, poly(tetramethylene oxide) glycol and HEMA. Dynamic mechanical analysis showed that the resultant IPN membranes have good compatibility between their constituents. As the HPU content increased, the tensile strength of the IPNs first increased and then decreased. For the highest tensile strength, the optimum HPU content was about 25 wt %. The value of surface tension of IPNs varied from 44.4 to 50.5 dyne/cm, and polarity ranged from 0.59 to 0.91. The relative index of platelet adhesion (RIPA) of the IPN membranes was measured by the dynamic thrombosis test at constant shaking speed and temperature. By the criteria of this test, the IPN membranes with HPU content of about 25 wt % have the minimum platelet adhesion. When measured by the angular dependent ESCA technique on the surface of IPN samples, the variation in the RIPA correlated to the change in the surface soft segment to hard segment ratio. Higher HPU content resulted in more migration of soft segments toward the surface. The platelet adhesion was observed to be minimized when the surface O/N ratio was around 12. © 1997 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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