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  • 1995-1999  (3)
  • 1985-1989  (3)
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 86-93 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodissociation of dimethylsulfoxide [(CH3)2SO] at 193.3 nm has been investigated using the molecular beam time-of-flight (TOF) mass spectrometric technique. In addition to CH3 and SO, CH3SO is also observed as a stable primary product, indicating that CH3SO+CH3 is an important product channel for the 193.3 nm photodissociation of (CH3)2SO. The analysis of the TOF data provides evidence that SO is formed via a stepwise mechanism: (CH3)2SO+hν (193.3 nm)→CH3SO+CH3→2CH3+SO. The analysis also indicates that (approximate)53% of the primary CH3SO radicals undergo further dissociation to produce CH3+SO, yielding a quantum yield of (approximate)1.53 for CH3. Within the sensitivity of our experiment, the product channel of CH3SCH3+O is not found. The angular distribution for the formation of CH3SO+CH3 is found to be isotropic, an observation consistent with a predissociation mechanism, in which the dissociation of photoexcited (CH3)2SO is slow compared to its rotational period. The energetics for selected dissociation reactions of (CH3)2SO have also been investigated by ab initio calculations at the G2(MP2) level of theory. The experimental dissociation energy at 0 K (53±2 kcal/mol) for the CH3–SOCH3 bond obtained here is in excellent agreement with the theoretical prediction of 52.6 kcal/mol. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 82 (1995), S. 201-203 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 82 (1995), S. 201-203 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Research in experimental medicine 188 (1988), S. 397-403 
    ISSN: 1433-8580
    Keywords: Ca2+ ; Arterial smooth muscle ; Spontaneously hypertensive rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Alterations in cellular calcium metabolism in essential hypertensive and in the SHR have been described. In the present study, particle-induced X-ray emission (PIXE) was used to get some information on the spatial distribution of Ca2+ in aortas of spontaneously hypertensive rats (SHR) and normotensive controls aged 1 week, 4 weeks, and 12 weeks. It was found that the Ca2+ content was not elevated in the aortic smooth muscle of SHR aged 1 week (n = 9) as compared to normotensive controls (n = 8) (186.8 ± 89.9 µg Ca2+/g tissue vs 254.0 ± 73.7 µg Ca2+/g tissue. The Ca2+ content was significantly raised in the aortic smooth muscle of SHR aged 4 weeks (n = 9) as compared to 4-weeks-old WKY rats (n = 12) (726.0 ± 130.4 Ca2+/g tissue vs 440.3 ± 214.4 Ca2+ µg/g tissue and in SHR aged 3 months (n = 15) as compared to WKY rats (n = 12), respectively (3317.0 ± 734.0 µg Ca2+/g tissue vs. 1632.0 ± 569.6 µg Ca2+/g tissue). The results confirm the age-related increase in the arterial Ca2+ content in normotensive rats and demonstrate additionally that this age-related rise in arterial Ca2+ content is accelerated in SHR.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 83 (1985), S. 87-92 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The elemental composition of the human atheroselerotic popliteal artery was examined using the proton-induced X-ray-emission (PIXE) method. The application of a narrow proton beam (3×10 μm2) enabled us to determine not only the concentrations of Cl, K, Ca, Fe, Cu, Zn, Br and Pb, but also their localization in different artery-wall regions. The highest mean concentrations of Cl, K, Zn and Br were found in the tunica media. In the investigated sections the distribution of Ca and Fe varied: sometimes, these elements were prevalent in the tunica intima, whereas in other cases, the highest concentrations were observed in the tunica media or tunica adventitia. The concentration profiles of each element were characterized by many sharp, narrow peaks. The highest concentrations of Ca and Fe showed such high levels that only one explanation is possible, i.e. the presence of crystals. The correlation of Ca peaks with those of Zn and Fe is discussed. The usefulness of the micro-PIXE method for the investigation of biomedical materials is also considered.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 887-903 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A knee simulator was used to study the wear of carbon fiber reinforced UHMWPE(Poly Two) (Poly Two is a registered trademark of Zimmer, USA) tibial and patellar components against Ti-6Al-4V, titanium nitride (TiN)-coated Ti-6Al-4V, and cobaltchromium-molybdenum femoral components. The prostheses tested were regular sized Miller-Galante total knees mounted on 316L stainless steel fixtures using bone cement. An environmental chamber surrounded the knee and maintained bovine serum lubricant at 37°C. The specimens were tested using consecutive blocks of 464 level walking steps, 8 ascending stairs and 8 descending stairs for a total of 100,000 steps. The wear mechanisms found on the tibial components were scratching, carbon fiber associated damage, surface deformation, pitting, minor abrasion, and delamination. Three forms of carbon fiber associated damage were identified; fibers pulled from the surface, broken fibers, and UHMWPE removed from the surface fibers. The SEM evaluation revealed a pit forming mechanism. No correlation was found between femoral component material and tibial surface damage. Visual examination of the femoral components revealed no signs of wear or scratching on the cobalt-chromium-molybdenum or TiN-coated Ti-6Al-4V components. There were, however, many light surface scratches on the uncoated Ti-6Al-4V components, which were also observed in a supplementary test of an uncoated Ti-6Al-4V component tested with a conventional polyethylene tibial component.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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