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  • Articles: DFG German National Licenses  (21)
  • 1990-1994  (21)
  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is reported that Nd-Fe-B magnetic powders prepared by utilizing the HDDR (hydrogenation, disproportionation, desorption, and recombination) phenomena exhibit high coercivity, and the addition of Co, Ga, and Zr induces magnetic anisotropy in these powders. HDDR phenomena are caused by the heat treatment in hydrogen (H treatment) and subsequently in vacuum (V treatment). Present works describe the effects of V-treatment conditions on magnetic properties of Nd12.6Febal.CoxB6.0 (x=0–17.4) alloys. The powders V-treated at lower temperature show lower remanence and no noticeable magnetic anisotropy. V treatment at higher temperature enhances remanence and increases the differences of remanence between the powders aligned with and without magnetic field. Higher values are obtained in Co added alloys. This result suggests that a selective grain growth of Nd2Fe14B grains during V treatment plays an important role for the inducement of magnetic anisotropy in HDDR-treated powders. The temperature for complete recombination reaction under evacuating condition decreases with increasing Co content. It can be said that Co addition enhances recombination reaction and results in acceleration of grain growth.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6477-6479 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of composition and additives on the microstructures and magnetic properties of Nd-Fe-B melt-spun ribbons were studied. Experimental results have revealed that homogeneous grain structure with fine grain size was obtained on composition close to 2-14-1 stoichiometry with additives. It was also found that Nb was very effective in increasing both remanence and coercivity in a Nd-Fe-B melt-spun ribbon. A high-energy product of 151.2 kJ/m3 (19.0 MGOe) was obtained from an isotropic (Nd0.5Pr0.5)12Fe72Co8B6Nb2 melt-spun ribbon with a remanence of 0.926 T and a coercivity exceeding 1200 kA/m (∼15 kOe).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3111-3114 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Infrared absorption, electron paramagnetic resonance (EPR) spectra, and the electrical resistivity of semi-insulating liquid encapsulated Czochralski GaP crystals irradiated by fast neutrons with a dose of 7.6×1018 n cm−2 have been studied. The electrical resistivity decreases with irradiation from 106 Ω cm to 1.5 kΩ cm. The temperature dependence of resistivity at low temperature is fitted to exp(b/T1/4). The strong continuous optical absorption extends to 0.32 eV and its tail spreads until 0.12 eV. The EPR spectrum exhibits a broad singlet at 77 K and a doublet with five line structures at room temperature, which is attributed to antisite defects PGa. The strong infrared absorption begins to be annealed at 150 °C, and the EPR broad singlet decreases with anneals in the same temperature range. The strong infrared absorption is assumed to arise from interstitial phosphorus clusters. A discussion is given concerning the species responsible for the EPR singlet.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 3087-3089 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of electron-wave interference effects in a structure which is comprised of a split-gate point contact with a parallel reflector gate is reported. The structure constricts the injected electrons to a waveguide. The variation of point contact conductance with reflector voltage has novel oscillations directly related to the one-dimensional (1D) states in the waveguide. The oscillations are caused by the change in matching between a mode for the 1D waveguide state and an electron wave injected into the states. The oscillations are also found to be quenched with weak magnetic fields due to electron wave deflection. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 18 (1991), S. 0 
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The authors report the functional analysis of the purified mouse factor H allotypes H. 1 and H.2, which were clearly distinguished from each other by an immunodiffusion test. Both allotypes acted as a co-factor for factor I in cleaving mouse C3b and we found no significant difference between their activities. The results strongly suggest that the function of mouse factor H for the co-factor activity has been well conserved between two allotypes.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 6 (1993), S. 147-152 
    ISSN: 1432-2145
    Keywords: Porogamy ; Syngamy ; Incongruity ; Unilateral cross-incompatibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The failure of pollen-tube dissolution in the synergid region, with subsequent pollen-tube overgrowth well into the central cell, was observed within embryo sacs following interspecific crosses between Solanum melongena and S. sisymbriifolium and between Lycopersicon esculentum and L. peruvianum. Such pollen-tube hypertrophy (PTH) was examined under fluorescence using both light and confocal microscopy in order to characterize this anomalous pollen-tube behavior and to verify its occurrence within the embryo sac central cell. Three genetically unrelated L. esculentum cultivars (‘Peto 95’, ‘Apex 1000’, ‘Nagcarlang’) were utilized as the female parents in interspecific pollinations with L. peruvianum accession LA 1708, and seed set was obtained from all crosses. It was observed that PTH was not a rare event in these crosses, with the proportion of PTH ranging from 2.6% to 6.5% of all ovules examined. Self-pollinated controls revealed zero (e.g., ‘Nagcarlang’) to extremely low (〈0.01%) frequencies (‘Apex 1000’ and ‘Peto 95’). The differences in frequencies suggests that the specific genotypes of the parents has an affect on the occurrence of successful pollen-tube dissolution and sperm-nuclei transfer. Pollen-tube hypertrophy represents a poorly understood, though easily identified, form of fertilization failure occurring within the ovule. Its conspicuous nature, along with a relatively high frequency of occurrence in certain crossing combinations, should provide a valuable opportunity to better study the nature of such fertilization failures in angiosperms.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2307
    Keywords: Interleukin ; Tumour necrosis factor Glomerulonephritis ; Monocytes ; Macrophages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the expression of inflammatory cytokines in renal tissues obtained from 45 patients with several types of glomerulonephritis. Immunofluorescence studies with specific antibodies to interleukin (IL)-1α, IL-1β, IL-6, tumour necrosis factor (TNF)-α, and TNF-β showed intense cytoplasmic staining in the glomeruli and interstitium. Cells positive for these cytokines were found frequently in tissue from patients with lupus nephritis (WHO Class IV) and membranoproliferative glomerulonephritis, and, to a lesser extent, in tissue from patients with mesangial proliferative glomerulonephritis, Henoch-Schönlein purpura nephritis, and minimal change nephrotic syndrome. Most of these cells were dual-stained with a monoclonal antibody to monocytes-macrophages. In situ hybridization for cytokine mRNA, combined with immunoperoxidase staining for monocytes-macrophages, detected IL-1α, IL-6, and TNF-α mRNA in monocytes-macrophages infiltrating the glomeruli and interstitium. Occasionally, there was weak or moderate immunostaining for IL-1α, IL-6, and TNF-α in the glomerular mesangial and epithelial cells, but in situ hybridization signals were rarely found in these loci. These findings suggest that infiltrating monocytes-macrophages, rather than resident glomerular cells, are the major source of inflammatory cytokines in human glomerulonephritis.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1920
    Keywords: Myelopathy ; Spinal draining veins ; Spontaneous carotico-cavernous fistula ; Recurrence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 45-year-old woman developed a myelopathy 9 years after a spontaneous left caroticocavernous fistula (CCF) was treated by a trapping procedure, with clipping distal to the fistula and ligation of the common carotid artery. Spinal MRI and vertebral angiography revealed recurrence of the CCF and gigantic tortuous veins draining through the brain stem down to the midcervical spinal cord. The abnormal veins and myelopathy disappeared after surgical closure of the CCF.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 1237-1239 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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