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  • 1995-1999  (17)
Material
Year
  • 11
    ISSN: 1434-601X
    Keywords: PACS:14.60.Cd Electrons and positrons – 23.20.Ra Internal pair production – 25.70.Bc Elastic and quasielastic scattering – 25.70.De Coulomb excitation – 25.70.Hi Transfer reaction – 29.30.Aj Charged-particle spectrometers: electric and magnetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We present the results of a Doppler-shift correction to the measured e+e−–sum-energy spectra obtained from e+e−–coincidence measurements in 238U +206Pb and 238U +181Ta collisions at beam energies close to the Coulomb barrier, using an improved experimental setup at the double-Orange spectrometer of GSI. Internal-Pair-Conversion (IPC) e+e− pairs from discrete nuclear transitions of a moving emitter have been observed following Coulomb excitation of the 1.844 MeV (E1) transition in 206Pb and neutron transfer to the 1.770 MeV (M1) transition in 207Pb. In the collision system 238U +181Ta, IPC transitions were observed from the Ta-like as well as from the U-like nuclei. In all systems the Doppler-shift corrected e+e−–sum-energy spectra show weak lines at the energies expected from the corresponding γ–ray spectra with cross sections being consistent with the measured excitation cross sections of the γ lines and the theoretically predicted IPC coefficients. No other than IPC e+e−–sum-energy lines were found in the measured spectra. The transfer cross sections show a strong dependence on the distance of closest approach (Rmin), thus signaling also a strong dependence on the bombarding energy close to the Coulomb barrier.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1573-2576
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We analyzed DNA-fragmentation in human polymorphonuclear neutrophil granulocytes (PMNs) from healthy donors after addition of exogenous arachidonic acid (AA) and eicosapentaenoic acid (EPA) by flow cytometry (propidium iodide staining of DNA and DNA strand break detection). The PMNs were incubated from 30 min up to 48 hours in RPMI 1640 which was supplemented with different concentrations of AA or EPA (5–40 μM). In contrast to EPA the addition of AA led to a significant increase in apoptosis up to 67.8% compared to the RPMI-control whereas the addition of EPA led to an inhibition of DNA-fragmentation. When the cells were incubated with MK 886 (1μM, inhibitor of leukotriene biosynthesis) an increase in DNA-fragmentation (up to 63.3%) was observed. Conversely, in the presence of indomethacin (1μM, inhibitor of prostanoid synthesis) an inhibition in DNA-fragmentation (up to 60.9%) occurred. Furthermore, preincubation of PMNs with pentoxifylline (1mM, phosphodiesterase inhibitor) reduced AA-stimulated DNA-fragmentation up to 43.4%. These data provide evidence for the involvement of AA and distinct AA metabolites in the regulation of apoptosis in human PMNs.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation 20 (1996), S. 71-85 
    ISSN: 1573-2576
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We analyzed the effect of the PAF receptor antagonist (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride (SM-12502) on human platelet aggregation as well as mediator release. After incubation of human platelet with different concentrations of SM-12502 the cells were subsequently stimulated with either the Ca ionophore A23187, with human thrombin, or with an activator of heterotrimeric G-proteins, sodium fluoride (NaF, in the presence of Al3+). Preincubation of platelets with the PAF receptor antagonist led to an inhibition of 12-lipoxygenase derived 12(S)-HETE and cyclooxygenase derived 12(S)-HHT. Pretreatment of platelets with the PAF receptor antagonist SM-12502 prior to activation with the Ca ionophore A23187 or PAF also inhibited platelet aggregation. Our data clearly indicate an inhibitory effect of the new PAF receptor antagonist SM-12502 on the formation of platelet derived inflammatory mediators of the lipoxygenase pathway as well as of the cyclooxygenase pathway, and furtherone, treatment with the PAF receptor antagonist diminished platelet aggregation after subsequent specific and unspecific activation.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 525-536 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Temperature of cutting tools by thin filmsDuring the cutting process, cutting tools are exposed to complex mechanical, thermal, dynamic and tribological loads. Especially in the case of dry machining the demands on cutting tools are very high. Dry machining becomes more and more interesting because of tightened up ecolaws and increased costs for the handling of coolants. Due to a renunciation on coolants the cutting tools need to be modified to the process of dry machining. Thereby modern plasma and ion based surface technologies can be used to deposit a thin film adopting the functions of coolants, e.g. cooling and lubricating.In this research project several coating types, e.g. titanium and chromium based coatings, where developed and characterized regarding their mechanical, tribological and thermal properties. For the research, four partners collaborated permuting all steps of surface and coatings design. Materials Science Institute (WW), Aachen University of Technology, performed the development of PVD coatings and the thermophysical characterization by thermal wave analysis. Surface modifications of uncoated and coated tools by ion beam assisted deposition were carried out at Stiftung Institut für Werkstofftechnik (IWT), Bremen. To determine the cutting properties of coated tools, practical tests were performed at Laboratory for Machine Tools and Production Engineering (WZL), Aachen University of Technology.
    Notes: Zerspanwerkzeuge sind während ihres Einsatzes einem komplexen und schwer zu erfassenden Beanspruchungskollektiv ausgesetzt. Dieses wird besonders durch die aus ökonomischen und ökologischen Gründen angestrebte Trockenzerspanung beeinflußt. Der vollständige Verzicht auf Kühlschmierstoffe bedeutet aus technologischer Sicht, daß Werkzeuge, Schneidstoffe und Zerspanoperationen auf die Bedingungen der Trockenzerspanung umgestellt werden müssen. Dabei bieten moderne ionen-und plasmagestütze Oberflächentechnologien insofern einen Lösungsansatz, daß durch Beschichtungen bzw. Oberflächenmodifikationen wichtige Aufgaben der Kühlschmiermittel durch den beschichteten Schneidstoff selbst übernommen werden können. Dies sind vor allem der Ersatz von Schmierung und Kühlung.Für den Bereich der Trockenzerspanung wurden im Rahmen eines Verbundvorhabens u.a Titanbasisschichten sowie Chrombasisschichten entwickelt und hinsichtlich der physikalischen Eigenschaften untersucht. Durch die enge Zusammenarbeit der beteiligten Forschungsstellen konnte das jeweils vorhandene Erfahrungspotential vollständig in die Schichtsystementwicklung einfließen. Diese umfaßte alle iterativen Schritte des Schichtmodifikation, begleitende Schichtanalytik bis hin zum Praxistest. So war beispielsweise das Lehr- und Forschungsgebiet Werkstoffwissenschaften der RWTH Aachen für die Schichtentwicklung sowie fü die thermophysikalische Charakterisierung der Schichten zuständig. Die Stiftung Institut für Werkstofftechnik, Bremen, führte eine Optimierung der Interfaces und der Hartstoffschichten mittels ionenstrahlgestützter Beschichtungsverfahren durch. So konnte das Substrat vor bzw. die Hartstoffschicht nach der Beschichtung an den Anwendungsfall angepaßt werden. Die Untersuchung hinsichtlich der Praxistauglichkeit der beschichteten Schneidstoffe erfolgte am Werkzeugmaschinenlabor der RWTH Aachen durch entsprechende Zerspanversuche.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical microbiology & infectious diseases 17 (1998), S. 519-521 
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the prevalence of resistance amongHelicobacter pylori in Germany, the minimum inhibitory concentrations of amoxicillin, tetracycline, clarithromycin, and metronidazole were determined by means of the E test, for 271Helicobacter pylori isolates cultured from biopsies taken during routine endoscopies in 1996 and 1997. The prevalence of metronidazole resistance was 32.1%, with resistance found more frequently in women (38.5%) than in men (24.4%). Clarithromycin resistance was rare (3.3%). Eight of nine strains resistant to clarithromycin were also resistant to metronidazole. Resistance to either metronidazole or clarithromycin was significantly (P=0.022) higher in patients with duodenal ulcer. No strain was found to be resistant to amoxicillin or tetracyline.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Kardiologie 87 (1998), S. s003 
    ISSN: 1435-1285
    Keywords: Schlüsselwörter Koronare Herzkrankheit – Myokardinfarkt – Inzidenz – Letalität – regionale Unterschiede – zeitliche Trends – medizinische Versorgung ; Key words Coronary heart disease – myocardial infarction – incidence – case fatality – regional differences – time trends – medical care
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The incidence of acute myocardial infarction (AMI) shows large regional differences. This variability cannot be completely explained by differences in classical risk factors. 28-day case fatality of AMI remains unacceptably high with 50% on the average, although therapeutic possibilities have improved considerably. Time trends in mortality from ischaemic heart disease (IHD) show a decrease in most Western European countries and an increase in Eastern Europe. On a population level, the impact of medical care on the short-term and long-term prognosis of AMI is not completely understood. Despite considerable progress in primary and secondary prevention, the incidence and prevalence of IHD will increase in the future due to aging of the population.
    Notes: Zusammenfassung Die Inzidenz des akuten Myokardinfarktes (AMI) zeigt ausgeprägte regionale Differenzen. Diese Variabilität ist nicht allein durch Unterschiede in den klassischen Risikofaktoren erklärbar. Die 28-Tage Letalität des AMI ist trotz verbesserter therapeutischer Möglichkeiten unverändert hoch und beträgt weltweit im Mittel 50%. Zeitliche Trends der Mortalität der koronaren Herzkrankheit (KHK) zeigen eine Abnahme in den meisten westeuropäischen Ländern und eine Zunahme in Osteuropa. Der Einfluß der medizinischen Versorgung auf die Prognose des AMI ist auf Bevölkerungsebene nur teilweise nachvollziehbar. Trotz der Fortschritte in der Primär- und Sekundärprävention wird die Inzidenz und Prävalenz der KHK in Zukunft aufgrund der ungünstigen Entwicklung der Altersstruktur der Bevölkerung weiter zunehmen.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 36 (1997), S. 159-160 
    ISSN: 0570-0833
    Keywords: cycloalkenes ; enantiomeric resolution ; hydrocarbons ; strained molecules ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract.For corrigendum see DOI:10.1002/anie.199704121
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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