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  • 2000-2004  (4)
  • 1955-1959
  • 2000  (4)
  • 1
    Digitale Medien
    Digitale Medien
    Dynamic study of the surfaces of (001) gallium arsenide in metal-organic vapor-phase epitaxy during arsenic desorption (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 1245-1250 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have investigated by reflectance anisotropy spectroscopy the arsenic desorption from GaAs (001) at various temperatures in metal–organic vapor-phase epitaxy to obtain reaction orders and activation energies. The highest arsenic coverage, found at low temperatures with arsine stabilization, corresponds to a (4×3) reconstruction. Without arsine, arsenic starts to desorb and less arsenic-rich reconstructions are observed, depending on temperature: c(4×4) (below 800 K), β2(2×4) (below 920 K), α(2×4), and only with hydrogen carrier gas finally (4×2) (above 950 K). Above 920 K the reaction order differs in hydrogen and nitrogen atmosphere, probably due to an etching effect of hydrogen radicals. The five different desorption processes show either a first- or zero-order time dependence. First order is related to the desorption from the terraces and zero order to desorption from the steps (or kinks) on the surfaces. The activation energies for all processes are around 2.5 eV. This energy is, therefore, assumed to be the activation energy for the removal of an arsenic dimer from the surface. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.372003
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  • 2
    Digitale Medien
    Digitale Medien
    Design and performance of a highly efficient mass spectrometer for molecular beams (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 2015-2018 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We present a very efficient 90° sector magnet mass spectrometer detector, based on electron impact ionization, especially adapted for the use with atomic and molecular beams. In this setup, a cylindrically symmetric magnetic field compresses electrons emitted from a large filament into a long, narrow volume containing primarily the molecular beam. This has the advantage of both producing as little as possible background from residual gases and increasing the interaction region between beam and ionizer. Experimental tests using thermal He atoms show that the detector's efficiency and sensitivity are very high, amounting to η≥0.70±0.04% and S=0.22±0.03 A mbar−1, respectively. The unconventionally long ionization volume, however, may restrict the use of this mass spectrometer to experiments with no, or only moderate timing requirements. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150570
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  • 3
    Digitale Medien
    Digitale Medien
    Seltene Ursache bei Muskelschmerzen und erhöhter Creatinkinase – das paroxysmale nicht-hereditäre Angioödem (2000)
    Springer
    Zeitschrift für Rheumatologie 59 (2000), S. 200-204 
    Details
    ISSN: 0340-1855
    Schlagwort(e): Schlüsselwörter Paroxysmales nicht-hereditäres Angioödem – Rhabdomyolyse – Myositis ; Key words¶Capillary leak syndrome – rhabdomyolysis – myositis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Systemic capillary leak syndrome is a rare idiopathic disorder characterized by recurrent episodes of hypotension and hemoconcentration due to sudden transient extravasation of up to 70% of plasma. Less than 40 cases have appeared in the literature. Mortality rates 5 years after diagnosis have been reported to be up to 75%. Clinical findings are generalized edema and intravasal fluid deficiency. Laboratory features include hypoalbuminemia and extreme hemoconcentration. A common finding is a monoclonal gammopathy. Rare manifestation of this syndrome is rhabdomyolysis due to increased compartment pressure and ischemic myonecrosis. Early diagnosis and exclusion of other clinical disorders like rheumatic myopathies and myositis are critical concerning prognosis and therapy. We describe a 46-year-old woman with rhabdomyolysis and systemic capillary leak syndrome whose condition is stable for a total of 30 months under a prophylactic regimen with oral terbutaline plus theophylline. A brief survey of the literature is given.
    Notizen: Zusammenfassung Gefäßprozesse stellen bei vielen entzündlich-rheumatischen Erkrankungen die pathophysiologische Grundlage dar. Wir stellen ein Krankheitsbild vor, das durch rezidivierende Perioden erhöhter Kapillarpermeabilität mit ausgeprägtem Flüssigkeitsstrom in extravaskuläre Kompartimente gekennzeichnet ist. Das paroxysmale nicht-hereditäre Angioödem („Clarkson-Syndrom”) betrifft meist Patienten unter 50 Jahren, die 5-Jahres-Mortalität liegt bei bis zu 〉75%. Kardinalsymptome sind generalisierte Ödeme bei gleichzeitig intravasalem Volumenmangel, dadurch treten oft bedrohliche Schocksituationen auf. Laborchemisch pathognomonisch in der akuten Phase sind Hypoproteinämie und extreme Hämokonzentration. Gehäuft findet sich eine monoklonale Gammopathie. Die im Rahmen eines begleitenden Kompartmentsyndroms auftretende Rhabdomyolyse mit Anstieg der Creatinkinase und Myalgien stellt eine Differentialdiagnose zu entzündlich-rheumatischen Erkrankungen dar. Wir beschreiben eine 46-jährige Patientin mit Rhabdomyolyse, bei der im Verlauf die Diagnose eines paroxysmalen nicht-hereditären Angioödems gestellt wurde und geben einen kurzen Überblick über das Krankheitsbild.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003930070081
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  • 4
    Digitale Medien
    Digitale Medien
    A phase II study of paclitaxel in chemonaïve patients with recurrent high-grade glioma (2000)
    Springer
    Annals of oncology 11 (2000), S. 409-413 
    Details
    ISSN: 1569-8041
    Schlagwort(e): paclitaxel ; quality-of-life ; recurrent high-grade glioma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Background:The prognosis of malignant gliomas remains poor. Inrecurrent disease, chemotherapy can be considered. Patients and methods:In this phase II study we determined theanti-tumour efficacy of paclitaxel 200 mg/m2 in a three-hourintravenous infusion every three weeks in chemonaïve patients withrecurrent high-grade glioma in terms of response, survival, and quality oflife. Results:In 17 patients (14 glioblastoma multiforme, 3 anaplasticastrocytoma) 69 paclitaxel cycles were administered. Partial or completeresponses were not observed. Stable disease for four to six months wasobserved in five patients (29%). Median time to progression and mediansurvival were two and 10 months, respectively. Toxicity due to paclitaxel wasas to be expected and minor in most cases. Quality of life and mood estimatesappeared rather stable over time. Conclusions:We conclude that three-weekly 200 mg/m2paclitaxel chemotherapy for patients with recurrent high-grade gliomas did notlead to major complications or adverse effects on quality of life and mood.However, this therapy is of only very limited value in terms of response andsurvival in such patients.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008376123066
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