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  • 1
    Electronic Resource
    Electronic Resource
    Computational Blood Flow Modeling Based on In Vivo Measurements (1999)
    Springer
    Annals of biomedical engineering 27 (1999), S. 627-640 
    Details
    ISSN: 1573-9686
    Keywords: Hemodynamics ; Aorto–iliac bifurcation ; MRI ; Rabbits ; In Vivo ; Wall shear stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Study of the relationship between hemodynamics and atherogenesis requires accurate three-dimensional descriptions of in vivo arterial geometries. Common methods for obtaining such geometries include in vivo medical imaging and postmortem preparations (vessel casts, pressure-fixed vessels). We sought to determine the relative accuracy of these methods. The aorto–iliac (A/I) region of six rabbits was imaged in vivo using contrast-enhanced magnetic resonance imaging (MRI). After sacrifice, the geometry of the A/I region was preserved via vascular casts in four animals, and ex situ pressure fixation (while preserving dimensions) in the remaining two animals. The MR images and postmortem preparations were used to build computer representations of the A/I bifurcations, which were then used as input for computational blood flow analyses. Substantial differences were seen between MRI-based models and postmortem preparations. Bifurcation angles were consistently larger in postmortem specimens, and vessel dimensions were consistently smaller in pressure-fixed specimens. In vivo MRI-based models underpredicted aortic dimensions immediately proximal to the bifurcation, causing appreciable variation in the aorto–iliac parent/child area ratio. This had an important effect on wall shear stress and separation patterns on the “hips” of the bifurcation, with mean wall shear stress differences ranging from 15% to 35%, depending on the model. The above results, as well as consideration of known and probable sources of error, suggests that in vivo MRI best replicates overall vessel geometry (vessel paths and bifurcation angle). However, vascular casting seems to better capture detailed vessel cross-sectional dimensions and shape. It is important to accurately characterize the local aorto–iliac area ratio when studying in vivo bifurcation hemodynamics. © 1999 Biomedical Engineering Society. PAC99: 8719Uv, 8761Lh
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.221
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  • 2
    Electronic Resource
    Electronic Resource
    The rotational barrier of an enaminonitrile. Charge and energy redistribution during rotation about the C-N bond (1997)
    Springer
    Structural chemistry 8 (1997), S. 13-19 
    Details
    ISSN: 1572-9001
    Keywords: Enaminonitrile ; CHELPG ; potential-derived charges ; PROAIM ; rotational barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ab initio quantum mechanical techniques were used together with PROAIM electron density partitioning and CHELPG electrostatic potential analysis to examine the charge density distribution of model enaminonitrile1 in its planar ground state and in its two rotational transition states. The barrier to rotation about the C-N bond was calculated to be 15.4 and 15.6 kcal/mole for the two rotational transition states at the HF/6-31G** level of theory, and was found to originate from a redistribution of electronic kinetic energy between the amino group and the rest of the molecule in a manner similar to that found for formamide and sulfonamide. Similarly, the C-N bond length and amino group electron population were found to depend upon the C-N torsional angle. Electrostatically derived atomic point charges were also examined at each stationary point using the CHELPG program. CHELPG electrostatic potential results were found to represent the traditional “external” viewpoint of the charge density consistent with a resonance model, while the results from PROAIM calculations were found to describe the underlying charge density and kinetic energy density redistribution responsible for the rotational barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272343
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  • 3
    Electronic Resource
    Electronic Resource
    Anionic polymerization of caprolactam. Optimization of the system NaH/N-benzoyl caprolactamThis contribution is dedicated to Professor Dr. H. Kämmerer on the occasion of his 65th birthday (1976)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 55 (1976), S. 141-154 
    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: Der Einfluß der Konzentration von Natriumhydrid als Katalysator und N-Benzoylcaprolactam als Cokatalysator auf die Polymerisation von ε-Caprolactam wurde untersucht. Dazu wurde die Änderung der Grenzviskositätszahl der entstandenen Polymeren in m-Kresol bei 25°C bestimmt. Auch der Einfluß der Polymerisationstemperatur wurde bei konstanter Konzentration von Katalysator und Cokatalysator auf die gleiche Weise untersucht.Obwohl die Reproduzierbarkeit der mittleren Molekulargewichte schwankte, kann man die folgenden Aussagen machen: Der höchste Wert der Viskositätszahl wurde für die niedrigste Konzentration des Cokatalysators erhalten. Die Viskositätszahl der Polymeren erreichte einen Maximalwert bei einer Katalysatorkonzentration von 1,8 mol-% für Cokatalysatorkonzentrationen von 1 und 2 mol-%, jedoch ergab sich bei höheren Konzentrationen an Cokatalysator kein klares Maximum. Im Bereich von 120-200°C ergab sich die höchste Viskositätszahl für die niedrigste Polymerisationstemperatur.
    Notes: The effects of changes in concentration of sodium hydride as catalyst, and N-benzoyl caprolactam as cocatalyst upon the polymerization of ε-caprolactam were studied. The effects were monitored as changes in the intrinsic viscosity of the resultant polymer determined in m-cresol at 25°C. Effects of changes in polymerization temperature at constant catalyst and cocatalyst concentration were also studied.Reproducibility of a given average molecular weight was variable. The highest value of intrinsic viscosity resulted from the lowest cocatalyst concentration studied. Intrinsic viscosity of the product reached a peak at 1.8 mol-% catalyst for 1 and 2 mol-% cocatalyst, but no clear peak occurred at the higher cocatalyst concentrations studied. The highest intrinsic viscosity resulted from the lowest polymerization temperature in the range from 120-200°C.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1976.050550112
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  • 4
    Electronic Resource
    Electronic Resource
    Charles Gilbert Overberger: A personal and professional appreciation (1990)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 28 (1990), S. 439-446 
    Details
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1990.140281307
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  • 5
    Electronic Resource
    Electronic Resource
    Silver triflate catalyzed copolymerization of 1,3-cyclohexadiene and 2-chloroacrylonitrile (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 591-593 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.170230233
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  • 6
    Electronic Resource
    Electronic Resource
    Thermally initiated crosslinking of an unsaturated heterocyclic polyester (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 2407-2409 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1978.170160928
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  • 7
    Electronic Resource
    Electronic Resource
    Polyenaminoesters from α,α′-bis(carbomethoxy)diacetylbenzenes and phenylene diamines (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 3029-3041 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyenaminoesters are prepared by condensation of α,α′-bis(carbomethoxy)diacetylbenzenes with phenylene diamines in the presence of N,N-dimethylaniline hydrochloride. Thermogravimetric analysis allowed the determination of the optimum temperature at which to conduct cyclization of the polymers to form thermally stable polypyridoquinolones. The structures of the polymers were assigned by spectroscopic comparisons with appropriate model compounds.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170181012
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  • 8
    Electronic Resource
    Electronic Resource
    Polyhydroxymethylfuroate [poly(2,5-furandiylcarbonyloxymethylene)] (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 863-864 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.170220336
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and polymerization of 3-Aza-8-oxabicyclo[3.2.1] octane-2-one (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 20 (1982), S. 521-523 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.130201002
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and polymerization of 2-oxo-3,8- dioxabicyclo [3.2.1] octane (1975)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 13 (1975), S. 333-336 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1975.130130603
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