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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 3847-3851 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-crystalline Bi nanowires with diameters ranging from 20 to 70 nm were prepared by electrodeposition using nanoporous aluminum oxide membranes rather than the more usual track-etched polycarbonate membranes. X-ray diffraction and selected area electron diffraction investigations revealed that the nanowires are essentially single crystalline and highly oriented. The temperature dependence of zero-field resistance of different diameter nanowires indicated that these Bi nanowires undergo a semimetal–semiconductor transition due to two-dimensional quantum confinement effects. The resistance maximum was observed at 50 K in zero magnetic field for 20 nm Bi nanowires, while the resistance minimum at 258 K for 50 nm Bi nanowires, due to the quantum size effect. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 1122-1124 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The morphologic and luminescent behaviors of various 4-(dicyanomethylene)-2methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) containing films have been investigated. This involves pure DCM layers deposited on top of a tris-(8-hydroxyquinoline) aluminum (Alq) layer or positioned between two Alq layer, DCM-doped Alq films, and periodically arranged Alq/DCM multilayer structures. The occurrence over a period of time of aggregation and permeation of DCM molecules at room temperature and at temperatures as low as ∼260 K is found in all the cases studied. Such a phenomenon will result in degradation of related organic light-emitting devices and is closely related to the electric polarity of the DCM molecule. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 60 (2005), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes:  Allergic asthma is characterized by airway hyper-responsiveness and chronic mucosal inflammation mediated by CD4+ Th2 lymphocytes. Regulatory CD4+CD25+ T cells are important components of the homeostasis of the immune system, as impaired CD4+CD25+ T cell activity can cause autoimmune diseases and allergy. The mechanism of suppression by CD4+CD25+ T cells remains controversial; different in vivo and in vitro studies raise possible roles for the immunosuppressive cytokines interleukin-10 and transforming growth factor-β, forkhead transcription factor Foxp3, glucocorticoid-induced tumor necrosis factor receptor, cytotoxic lymphocyte associated antigen-4, 4-1BB costimulator receptor, a CD4-related molecule LAG-3, and neuropilin-1. Current data suggest that Th2 responses to allergens are normally suppressed by CD4+CD25+ T cells. Suppression by CD4+CD25+ T cells is decreased in allergic individuals. Furthermore, CD4+CD25+ T cells play a key role in regulating airway eosinophilic inflammation. The immunomodulatory properties of CD4+CD25+ T cells do extend to Th2 responses, most notably by limiting the development of a proinflammatory CD4+ Th2 phenotype characterized by reduced cytokine production. An understanding of the roles of CD4+CD25+ T cells in vivo could provide better insight into the design of novel approaches to modulate the chronic airway inflammatory reaction evident in bronchial asthma.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 60 (2005), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  The serum soluble cytotoxic T lymphocyte associated antigen-4 (sCTLA-4) concentration is significantly elevated in patients with asthma, and sCTLA-4 concentration correlate with the severity of asthma. The aim of the present study was to investigate effects of allergen inhalation and oral glucocorticoid on concentration of serum sCTLA-4 in patients with allergic asthma.Methods:  Allergen inhalation challenge was conducted in allergic asthmatics with isolated early asthma response and those with dual asthma response. In a randomized, double-blind, placebo-controlled, parallel group fashion, prednisolone or placebo was give orally once a day for 2 weeks. Venous blood samples were collected before and after allergen inhalation or prednisolone administration for obtaining sera. The serum sCTLA-4 concentrations were determined using enzyme-linked immunosorbent assay.Results:  The serum sCTLA-4 concentrations in the dual responder group increased from 29.0 (14.5–43.7) μg/l [median (25–75 percentiles)] before allergen inhalation to 44.0 (24.3–61.3) μg/l 24 h after allergen inhalation. In the isolated early responders, there were no significant increase in serum sCTLA-4 concentrations after allergen inhalation compared with baseline levels. There was a significant decrease in serum sCTLA-4 concentrations after 2 weeks of glucocorticoid therapy [22.0 (15.5–31.0) μg/l] compared with baseline values [37.0 (19.5–53.0) μg/l], whereas there was no significant difference in the placebo group.Conclusion:  This study has demonstrated that serum sCTLA-4 concentrations increased after allergen inhalation in sensitized asthmatic subjects, and that serum sCTLA-4 concentrations were downregulated by prednisolone therapy.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 59 (2004), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Antigen-loaded eosinophils instilled intratracheally into mice were capable of migrating into local lymph nodes and localize to the T cell-rich paracortical zones where they stimulated antigen-specific proliferation of CD4+ T cells. The aim of the present study was to evaluate whether eosinophils within the tracheobronchial lumen can stimulate Th2 cell expansion by presenting antigen both in vitro and in vivo.Methods:  Airway eosinophils were recovered from ovalbumin-sensitized and -challenged BALB/c mice, these eosinophils were then co-cultured with sensitized CD4+ cells in the absence or presence of anti-CD80 or/and -CD86 monoclonal antibodies. Airway eosinophils were instilled into the trachea of sensitized mice. At 3 days thereafter, the draining paratracheal lymph nodes were removed and teased into cell suspensions for culture. Cell-free culture supernatants were collected for detection of cytokines.Results:  Our data showed that airway eosinophils functioned as CD80- and CD86-dependent antigen-presenting cells (APCs) to stimulate sensitized CD4+ lymphocytes to produce interleukin (IL)-4, IL-5, and IL-13, but not interferon (IFN)-γ in in vitro assay. When instilled intratracheally in sensitized recipient mice, airway eosinophils migrated into draining paratracheal lymph nodes primed Th2 cells in vivo for IL-4, IL-5, and IL-13, but not IFN-γ, production during the in vitro culture that was also CD80- and CD86-dependent.Conclusion:  Eosinophils within the lumina of airways could process inhaled antigen function in vitro and in vivo as APCs to promote expansion of Th2 cells. This investigation highlights the potential of eosinophils to not only act as terminal effector cells but also to actively modulate immune responses by amplifying Th2 cell responses.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2145
    Keywords: Key words Microprojectile bombardment ; Nicotiana tabacum ; De-exined pollen ; β-glucuronidase gene ; Green fluorescent protein gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Gene constructs containing the β-glucuronidase (GUS) gene or green fluorescent protein (GFP) gene under the control of pollen-specific promoter Zm13-260 from maize were introduced by particle bombardment into de-exined pollen of Nicotiana tabacum. The de-exined pollen exhibited transient expression of the GUS or GFP gene as indicated by histochemical and fluorescent assay, respectively. The frequency of de-exined pollen transformation with the GUS or GFP gene was approximately 6 and 3 times higher, respectively, than that of pollen with intact walls, indicating that pollen deprived of the exine barrier responded better to foreign gene transfer than did the original. Cytological observation of GUS-expressing pollen grains showed that introduced gold particles were visible in the cytoplasm and vegetative nucleus as well as in the generative nucleus. GFP-expressing pollen tubes were observed in the style even after pollination.
    Type of Medium: Electronic Resource
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