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  • 1
    Electronic Resource
    Electronic Resource
    Estimation of the linear thermal expansion coefficient in friction-deposited, oriented poly(tetrafluoroethylene) films by temperature-dependent lateral force microscopy (1996)
    Springer
    Polymer bulletin 36 (1996), S. 471-476 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Preliminary lateral force microscopy (LFM) results are presented which were obtained at different temperatures on thin films of poly(tetrafluoroethylene) prepared by friction deposition. Chain-chain distances of rodlike poly(tetrafluoroethylene) macromolecules were determined as a function of temperature from LFM images which exhibit molecular resolution. The value of the linear thermal expansion coefficient in the chain-perpendicular direction was estimated to be 3.5x10-3 [1/°C] in the temperature range between+10°C and+40°C. This value is higher than the literature data quoted for the temperature range between 0 °C and 25 °C. Possible reasons for this deviation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315065
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  • 2
    Electronic Resource
    Electronic Resource
    On-line measurement of nitric oxide release from organic nitrates in the intact coronary circulation (1991)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 344 (1991), S. 240-246 
    Details
    ISSN: 1432-1912
    Keywords: Glyceryl trinitrate ; Molsidomine (SIN-1) ; Langendorff rabbit heart ; EDRF ; Nitric oxide ; Intact organ circulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study determines the release of nitric oxide (NO) from the coronary circulation of Langendorff hearts of rabbits, subsequent to administration of glyceryl trinitrate (GTN) and SIN-1. NO was measured on-line in the coronary effluent by the oxyhaemoglobin technique. Infusion of either GTN (10–40 moles/l) or SIN-1 (0.1–2.3 μmoles/l) into the coronary inflow resulted in a concentration-dependent NO release into the coronary effluent and a decrease in the coronary vascular resistance. NO generation from SIN-1 was identical with and without passage of the coronary circulation whereas NO generation from GTN was only detected after passage of the coronary vascular bed. NO generation by both substances was in the same range as endogenous NO release by two endothelium-dependent vasodilators, bradykinin (0.05 μmoles/l) and substance P (0.05 μmoles/l). Oxyhaemoglobin used for the assay of NO, inhibited the relaxation by SIN-1, but did not reduce vessel relaxations induced by GTN or iloprost, a stable prostacyclin analogue. Removal of the coronary endothelium by trypsin or pretreatment with L-NG-Monomethyl-arginine (30 μmoles/l) did neither affect NO release from GTN and SIN-1 nor the vasodilatory effect of both substances. These data are the first to directly demonstrate endothelium-independent NO release from organic nitrates during passage of an intact organ circulation. They additionally suggest a subendothelial site of metabolic NO formation from GTN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167225
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Sulfur Compounds, 144 Synthesis of Sulfur-Rich Organic Polysulfanes Utilizing Titanocene Pentasulfide as a Sulfur-Transfer Reagent (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2357-2359 
    Details
    ISSN: 0009-2940
    Keywords: Heptasulfanes, cyclic ; Pentasulfane, linear ; Polysulfanes, organic, HPLC of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Titanocene pentasulfide, Cp2TiS5 (1) reacts with Ph3CCl (4), C2H4(SCl)2 (6), and CH3C6H3(SCl)2 (9) to give the corresponding polysulfanes (Ph3C)5 (5), C2H4S7 (7), and CH3C6H3S7 (8) which have been characterized by NMR, mass, and Raman spectroscopy. By interconversion reactions the mentioned polysulfanes yield homologous molecules with up to 11 sulfur atoms which have been separated by reversed-phase HPLC. Linear relationships between the capacity factor and the number of sulfur atoms in the molecule have been derived for each series, and retention indices have been calculated.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241032
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  • 4
    Electronic Resource
    Electronic Resource
    Anisotropic stick-slip friction of highly oriented thin films of poly(tetrafluoroethylene) at the molecular level (1996)
    Springer
    Tribology letters 2 (1996), S. 231-239 
    Details
    ISSN: 1573-2711
    Keywords: lateral force microscopy ; poly(tetrafluoroethylene) ; frictional anisotropy ; stick-slip motion ; molecular imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Lateral force microscopy (LFM) studies of poly(tetrafluoroethylene) (PTFE) films with molecular resolution are reported. Thin PTFE layers with a high degree of orientation were obtained by pressing and sliding a block of polymer on a clean, heated muscovite mica substrate. LFM nanographs obtained on these films by scanning at directions between ca. 40 and 90° with respect to the film orientation direction, i.e. with respect to the direction of the polymer chains, showed a “stick-slip” type frictional motion of the LFM probe tip at the molecular level. The friction force observed at constant load decreased with decreasing scan angles. Chain-chain packing distances obtained by LFM and contact-mode atomic force microscopy were the same to within the experimental error and had a value of 5.8 Å. Dual-mode contact AFM/LFM imaging was also performed by scanning in the chain direction. Here LFM nanographs showed no distinct “stick-slip” phenomenon. The contact mode AFM images, however, exhibited clear molecular resolution with the expected chain-chain periodicity. The disappearance of the “stick” component in LFM scans performed in the chain direction was attributed to the smooth surface of PTFE on the molecular scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173129
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    Paper (German National Licenses)
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