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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2447-2451 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: SnTe-doped InP layers were grown at low temperature by solid-source atomic layer molecular beam epitaxy. The samples were characterized by Hall measurements versus temperature, low temperature photoluminescence, x-ray diffraction, and secondary ion mass spectroscopy. The temperature of the SnTe effusion cell was varied from 320 to 440 °C, and the free electron concentration measured at room temperature ranged between 2.0×1016 cm−3 and 5.6×1018 cm−3 with the corresponding Hall mobility varying from 2320 to 1042 cm2/V s. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5881-5883 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have performed a temperature-dependent study of the rare earth L2,3 and Co K edges x-ray magnetic circular dichroism (XMCD) in HoCo2 and PrCo2. We have found in both samples that the L2/L3 ratio is temperature independent. This result contradicts previous findings that indicated a possible different behavior for L2 and L3 edges owing to modifications in the degree of 3d–5d hybridization. A further interesting result is that the temperature dependence of ratio E1/E2 for the L3 edge — where E1 and E2 correspond to the two area under the dichroic signal separated in two peaks, positive dipolar dominant, negative with significant contributions of both dipolar and quadrupolar channels — is also constant, suggesting that the dipolar and quadrupolar channels follow the same temperature dependence. This effect might be interpreted as the dominant 4f contribution to the 5d polarization (much larger than the 3d-induced contribution) to create the L-edge XMCD signal. The microscopic origin of the metamagnetic Co subsystem is also addressed. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1365-2230
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4891-4893 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A detailed nuclear magnetic resonance (NMR) study of some intermetallic compounds of the series Y1−xGdxCo3 is presented. These are results where the NMR lines corresponding to the four magnetic sites of these compounds appear clearly resolved in the NMR spectra. We found, however, that the number of lines and their widths are strongly dependent on the radio frequency (rf) power level, which may help to explain some of the discrepancies found in NMR literature on these compounds. From the dependence of the NMR spectra with rf power we concluded that the site labeled 18h presents the largest local magnetic anisotropy. No significant changes are observed in the value of the hyperfine fields at any site as a function of the Gd concentration, x. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd.
    Journal of the European Academy of Dermatology and Venereology 18 (2004), S. 0 
    ISSN: 1468-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2471-2473 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A method for the fabrication of nanometer size gold wires on insulating surfaces is presented. An oscillating gold-coated atomic force microscope tip is brought into close proximity of a silicon dioxide surface. The application of a negative sample voltage produces the transport of gold atoms from the tip to the surface. The voltage is applied when there is a tip–surface separation of ∼3 nm. The finite tip–surface separation enhances the tip lifetime. It also allows the application of sequences of multiple voltage pulses. Those sequences allow the fabrication of continuous nanowires. The atomic force microscope gold deposition is performed at room temperature and in ambient conditions which makes the method fully compatible with standard lithographic techniques. Electron transport measurements of the wires show a clear metallic behavior. Electrical resistivities of ∼3×10−7 Ω m and current densities of up to 5×1011 A m−2 are reported. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 52 (2000), S. 0 
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Following primary infection with human immundeficiency virus (HIV)-1, antibodies against specific HIV-1 epitopes are elicited. However, non-HIV-1 specific antibodies, including autoantibodies, also arise. In fact, it has been proposed that such autoantibodies have an important role in the pathogenesis of HIV-1 infection. Because an imbalance in connectivity has been associated with autoimmune processes, we investigated the connectivity status of HIV-1-infected individuals. Moreover, we tested the possible role of viral load and CD4+ T-cell counts, in connectivity, because these parameters appear to be important in the prognosis of HIV-1 infection. Results show that indeed, there is an alteration in connectivity in these patients, both for immunoglobulin (Ig)G and IgM, which is an immune alteration not previously identified in HIV-1 infection. In addition, our results show that viral load and CD4+ T-cell counts are both equally important in defining the characteristic pattern of connectivity in HIV-1-infected individuals, and that neither is independently responsible for alterations in patient connectivity status.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 60 (2004), S. 0 
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Cholesterol- and sphingolipid-rich membrane microdomains (lipid rafts) are widely recognized as portals for pathogenic micro-organisms. A growing body of evidence demonstrates mobilization of host plasma cell membrane lipid rafts towards the site of contact with several pathogens as well as a strict dependence on cholesterol for appropriate internalization. The fate of lipid rafts once the pathogen has been internalized and the nature of the pathogen components that interact with them is however less understood. To address both these issues, infection of the J774 murine cell line with Mycobacterium avium was used as a model. After demonstrating that M. avium induces lipid raft mobilization and that M. avium infects J774 by a cholesterol-dependent mechanism, it is shown here that mycobacterial phagosomes harbour lipid rafts, which are, at least in part, of plasma cell membrane origin. On the other hand, by using latex microbeads coated with any of the three fractions of M. avium-derived lipids of different polarity, we provide evidence that high-polarity, in contrast to low-polarity and intermediate-polarity, mycobacterial lipids or uncoated latex beads have a strong capacity to induce lipid raft mobilization. These results suggest that high-polarity mycobacterial lipid(s) interact with host cell cholesterol-enriched microdomains which may in turn influence the course of infection.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 60 (2004), S. 0 
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Infection by any of the four serotypes of dengue viruses (DEN-1, -2, -3 and -4) may result in either a relatively benign fever, called dengue fever (DF), a fatal disease, such as dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS). Several lines of evidence suggest that soluble immune response mediators may be involved in the severity of dengue infections. For instance, elevated seric levels of IL-8 are a common feature in DHF patients. Because other chemokines, cytokines, adhesion molecules, chemokine and cytokine receptors, as well as cytokine-related molecules may also be involved in dengue virus pathogenesis, we aimed at analysing the gene expression of such molecules in the course of an in vitro DEN-2 infection of human peripheral blood monocyte-derived macrophages, a cell type regarded as a primary target for DEN. Nylon membrane gene arrays containing 375 different human cytokine-related genes were used as a first step to search for differentially expressed genes upon infection. Transcripts for IL-8, IL-1β, osteopontin, GRO-α, -β and -γ, I-309, and some other molecules showed to be upregulated upon infection, whereas others such as MIC-1, CD27L and CD30L, were downregulated. Four genes were selected for reverse transcriptase-polymerase chain reaction based gene-expression analysis as a way to partially confirm microarray results. This approach pointed out 25 macrophage-expressed cytokine-related genes that could be relevant in DEN-2 pathogenesis.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Mitochondria are at the centre of molecular events involved in energy production, cell survival and apoptosis. Mitochondrial membrane potential (Δψm) is maintained by cellular catabolic reactions and the electron transport chain of which cytochrome c is a constituent, whereas the proton leak pathway, ATP synthesis and turnover consume it. Mitochondrial alterations such as a drop in Δψm, swelling and cytochrome c release have been observed in apoptosis. However, there is a paucity of information concerning mitochondrial function in the course of intracellular infections, a process that must certainly induce stress on the host cell. This work analyses the effect that two strains of mycobacteria of opposing virulence have on the mitochondria of murine macrophages in the early stages of infection. It was found that infection of J774 cells with both Mycobacterium tuberculosis H37Ra and M. tuberculosis H37Rv readily induced changes in Δψm as well as in mitochondrial morphology at the ultrastructural level. In addition, an increase in cytosolic ATP was found at 24 h post infection with both strains of M. tuberculosis. Interestingly, only M. tuberculosis H37Rv was able to induce cytochrome c release from mitochondria to the cytosol, thus suggesting the occurrence in M. tuberculosis H37Rv of a specific factor(s) capable of regulating cytochrome c translocation. The precise role of cytochrome c release in the context of a mycobacterial infection remains to be elucidated.
    Materialart: Digitale Medien
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