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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6178-6185 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: ZnSexTe1−x epilayers were investigated by means of luminescence, reflectivity, and temperature dependence in the concentration range 0〈x〈0.4. The studied ZnSexTe1−x epilayers with thicknesses of about 1.5 μm were grown on GaAs substrates by metalorganic vapor phase epitaxy. It was found that the luminescence and reflectivity spectra of the mixed crystals are strongly affected by the compositional disorder. A continuous transition from the recombination through free and bound exciton states to the recombination of excitons localized by the compositional fluctuations of the mixed crystal was observed in the concentration region of about x=0.25. The position of the excitonic band edge was derived from the photoluminescence excitation spectra and from temperature dependence of the emission spectra.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2581-2583 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Two sharp and intense emission bands with the maxima of 2.185 and 2.150 eV and a weak phonon coupling were investigated in the heteroepitaxial ZnTe layers. The study of the ZnTe layers grown on different substrates with thicknesses of 0.5–3.2 μm has shown that this luminescence is produced in the interface region that contains a high density of structural defects. The temperature dependence of these bands reveals the excitonic character of the recombination. We propose that the observed bands originate from the recombination of excitons localized at structural defects such as dislocations and associated defects.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Medicine 56 (2005), S. 1-16 
    ISSN: 0066-4219
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Medizin
    Notizen: During the past 15 years, important progress has been made in the understanding of the biology and prognosis of myelodysplastic syndrome (MDS). MDS is a clonal disorder characterized by ineffective hematopoiesis, which can lead to either fatal cytopenias or acute myelogenous leukemia (AML). Risk-adapted treatment strategies were established because of the high median age (60Đ??75 years) of the MDS patients and the individual history of the disease (number of cytopenias, cytogenetic changes, transfusion requirements). Allogeneic bone marrow transplantation currently offers the only potentially curative treatment, but this form of therapy is not available for the typical MDS patient, who is 〉60 years of age. Therapy with erythropoietin and G-CSF has improved the quality of life of selected patients. The development of small molecules directed against specific molecular targets with minimal adverse effects is the hope for the future. Innovative uses of immunomodulatory agents and the optimizing of cytotoxic treatment should continue to help in the treatment of MDS.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 27 (1994), S. 551-557 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A new method is developed for calculating the correlation function of the random deformation in heteroepitaxic layers and superlattices from measurements of iso-intensity contours of diffuse X-ray scattering. The method is based on the optical coherence approach and kinematical diffraction theory. Structural models have been found that enable the correlation functions to be calculated for various types of randomly placed defects (mosaic blocks and random elastic deformation). The applicability of the method has been demonstrated by measuring the diffuse X-ray scattering from a ZnTe layer grown on a GaAs substrate. The parameters characterizing the defects were obtained from a comparison of the calculated correlation function with theoretical models.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1546-170X
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Medizin
    Notizen: [Auszug] Infusion of endothelial progenitor cells (EPC), but not of mature endothelial cells, promotes neovascularization after ischemia. We performed gene expression profiling of EPC and endothelial cells to identify genes that might be important for the neovascularization capacity of EPC. Notably, the ...
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 143-147 (Oct. 1993), p. 567-572 
    ISSN: 1662-9752
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 3 (1993), S. 453-458 
    ISSN: 1432-1084
    Schlagwort(e): Liver ; Liver neoplasms ; Hepatocellular carcinoma ; MR studies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Nineteen patients with 28 histologically proven hepatocellular carcinomas (HCCs) were examined using T1- and T2-weighted spin-echo sequences and dynamic gadopentetate dimeglumine-enhanced magnetic resonance imaging (MRI) performed by fast T1-weighted gradient-echo sequence (100/5/80°) which was performed before and repeatedly (12 sets of images) after intravenous bolus injection of gadopentetate dimeglumine (Gd-DTPA) over a period of 10 min. Enhancement of HCC was heterogeneous in 24 lesions (85.7%). Intra-lesional non-enhancing areas were seen in 18 cases (64%). A late-enhancing pseudocapsule was seen in 12 lesions (42.9%). In addition, two groups were distinguished in the examined HCCs: 16 lesions (57.1%) showed stronger enhancement compared to liver parenchyma with maximum positive lesion-to-liver contrast on the 15-s images, while 12 lesions (42.9%) had an enhancement less than normal liver with a maximum negative contrast on the 15-s images. We conclude that the morphologic features most frequently encountered in HCC on dynamic Gd-DTPA-enhanced MRI are inhomogeneity of enhancement, intra-lesional non-enhancing areas, and relatively late enhancement of a pseudocapsule. Taking the degree of enhancement to be representative of the degree of vascularity, we also conclude that HCC can appear either hypervascular or hypovascular in the early phase of the dynamic study.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Langenbeck's archives of surgery 376 (1991), S. 257-263 
    ISSN: 1435-2451
    Schlagwort(e): Parenteral nutrition ; LCT-fat ; Yoshida sarcoma ; Tumor growth ; Nitrogen balance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In einer experimentellen Untersuchung an Sprague-Dawley-Ratten wurden die Auswirkungen von parenteral zugeführten LCT-Fetten auf das Tumorwachstum des Yoshida-Sarkoms in seiner Aszites form überprüft. Dabei wurden 4 Gruppen mit je 10 tumortragenden (TTR) and 10 nicht tumortragenden Ratten (NTTR) gebildet, denen parenteral LCT-Fette in unterschiedlicher Dosierung (Gruppe 1–3) zugeführt, bzw. die enteral ad libitum ernährt wurden (Gruppe 4). Es zeigt sich, daß die tumortragenden Ratten (TTR) cine höhere Stickstoffretention aufwiesen, als die nicht tumortragenden Ratten (NTTR). Dabei fiel auf, daß die NTTR einen höheren Stickstoffgehalt in der Muskulatur hatten. Der Stickstoffanteil nahm dabei mit zunehmendem Fettanteil ab. Die Betrachtung des Sarkoms ergab, daß sich sowohl der Stickstoffgehalt des Aszites, wie auch die Menge and die Zellzahl des Tumors umgekehrt proportional zur Menge des parenteral zugeführten Fettes verhielt. Für den Wirt konnten wir zeigen, daß er die zugeführten Energiemengen nicht unmittelbar für sich verwerten konnte. Der Tumor wächst nicht proportional mit der ihm zugeführten Energie, sondern muß sich vom Katabolismus des Wirtes ernähren.
    Notizen: Summary In an experimental study with sprague-dawley-rats we tested the effect of parenteral substituted LCT-fats on tumor growth of the Yoshida sarcoma in its ascites form. Therefore we tested 4 groups with 10 tumor-bearing and 10 non-tumor-bearing rats. We added group 1–3 LCT-fats in different doses. Group 4 was fed enterally. We found that tumor-bearing rats had a higher nitrogen retention than non-tumor-bearing rats. Non-tumor-bearing rats showed a higher nitrogen concentration in the muscles. The portion of nitrogen increased with increasing portion of fat. The content of nitrogen in the ascites, the quantity and the number of tumor cells was reversed in proportion to the portion of fat. For the host we showed that he cannot make use of the energy directly. The tumor does not grow in proportion to the available energy but has to support itself from the catabolism of the host.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1615-6102
    Schlagwort(e): Asters ; Microtubules ; Mitosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Using an antibody against tyrosinated tubulin and epifluorescence microscopy, mitosis was studied in three different microvessel endothelial cell types recently isolated from bovine corpus luteum. Dividing cells were flat and at certain stages individual microtubules could be followed for considerable lengths. The structure of the spindle apparatus and the course of mitosis were conventional. Microtubule asters were small from prophase until metaphase in all three cell types. However, whereas in two cell types telophase asters remained inconspicuous, prominent asters, of mostly straight microtubules, formed in telophase cells of a third cell type. Thus, aster size is heterogeneous between different endothelial cell types. Large microtubule asters are not regularly found in dividing cultured mammalian cells. The microendothelial cell types present themselves as appropriate systems for spindle research and especially for the study of aster microtubule dynamics and function.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 165 (1991), S. 51-63 
    ISSN: 1615-6102
    Schlagwort(e): Bivalent structure ; Meiosis ; Microtubules ; Mitochondria ; Nuclear envelope
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Using ultrathin sections and electron microscopy, the structure of prophase I spermatocytes is described in the mothEphestia kuehniella Z. Some stages were also examined using light microscopy and antitubulin immunofluorescence microscopy. Changes in the mitochondrial inventory, the endomembranes, and the nuclear content during the progression of meiosis from pachytene to diakinesis have a bearing on the structure of prometaphase and metaphase I spermatocytes. In late diplotene, a short-lived system of cytoplasmic microtubules forms independently of the flagellar bases. Possibly mediated by these microtubules, mitochondria gather in a portion of the cell and fusion of individual mitochondria occurs. The clustering of mitochondria, which persists until the meiotic spindle has developed, may be the prerequisite for the bipartition of the chondriome during cytokinesis. After late pachytene, the mass of perinuclear endoplasmic reticulum and the number and size of the Golgi stacks also increase. These endomembranes give rise to the multi-layered membraneous envelope around the meiotic spindle and probably to the intraspindle membrane system. After late pachytene, the number of nuclear pores also increases and material export from the nucleus is apparent. The exchange is interpreted as an indicator for transcriptional activity in the late prophase I nucleus when the chromatin is transiently decondensed (diffuse stage). In the course of chromatin recondensation, the bivalents assume a speckled appearance in ultrathin sections. Metaphase I bivalents possess lighter staining equatorial material. This material is not stained with a DNA-specific fluorescent dye or with acetic orcein, which preferentially binds to chromatin. It is hypothesized that less dense core material becomes interspersed with chromatin during the diffuse stage and is involved in the maintenance of bivalent structure until the onset of anaphase I.
    Materialart: Digitale Medien
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