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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2385-2389 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The stability of the Bi2−xPbxSr2Ca2Cu3O10 (Pb-2223) phase contained in silver-sheathed oxide-powder-in-tube specimens has been investigated by x-ray diffraction, transmission electron microscopy, and energy dispersive x-ray analysis. Silver tubes loaded with Pb-2223 precursor powders were processed into tapes using established metallurgical techniques. The tapes were heat-treated in a specially designed equilibration apparatus at selected temperatures (800–845 °C) for a range of times (10–5500 min) and quenched in liquid gallium held at ∼40 °C. The results showed that the Pb-2223 phase is stable in a limited temperature interval between 810 and 830 °C in 7.5% oxygen. At 800 °C, this phase decomposes to Bi2Sr2CaCu2O8 (2212), Ca2PbO4, and CuO; while at temperatures ≥840 °C it partially melts with precipitation of Bi2Sr2CuO6 (2201) and Ca2CuO3. The effects of the silver cladding on the Pb-2223 phase stability and microstructure are also discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By manipulating the cooling rate from the final heat treatment, we have raised the 77 K, self-field critical current density (Jc) of multifilament (Bi,Pb)2Sr2Ca2Cu3Ox (2223) tapes by a factor of 3, and the irreversibility field (H*) by more than 50%. The Jc of samples cooled in 7.5% O2 from their reaction temperature of 825 °C increased from ∼8 to ∼24 kA/cm2 and H*(77 K) increased from ∼120 to ∼200 mT as the cooling rate was decreased from 5 to 0.016 °C/min. The results unambiguously show that the flux pinning properties of 2223 tapes can be improved by simple changes in wire processing. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 690-692 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cross-section transmission electron microscopy was used to investigate the interaction of silver with (Bi,Pb)-Sr-Ca-Cu-O phases during the formation of (Bi2−xPbx)Sr2Ca2Cu3O10+δ (Bi-2223) in a silver-sheathed wire containing a powder composed of (Bi,Pb)2Sr2CaCu2O8+δ (Bi-2212) plus second phases. Observations of the interfacial regions of samples quenched at different stages of conversion revealed that (1) Bi-2212 is initially in direct contact with silver, with the (001) planes parallel to the interface; (2) an amorphous layer between Bi-2212 and silver appears during the induction period that precedes the conversion reaction; and (3) Bi-2223 is detected at the silver/powder interface hundreds of minutes before it begins to appear in regions of the powder away from the interface. The implications of these results are presented and discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transport critical current density Jc of oxide-powder-in-tube mono- and multifilamentary Bi-2223/Ag tapes has been determined before and after irradiation by 0.8 GeV protons at fluences up to 7.0×1016 protons/cm2. Proton-induced fission of the Bi nuclei produced up to 8.6×1013 fissions/cm3, creating long tracks at densities equivalent to matching fields up to 1.1 T. Relative to unirradiated tapes, Jc values at 75 and 64 K show no decrease in self field, indicating no breakdown of intergranular coupling, and show large, dose-dependent enhancements in magnetic fields oriented parallel to the tape normal. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1039-1041 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A considerable body of evidence collected on silver-sheathed (Bi,Pb)2Sr2Ca2Cu3O10+δ (Bi-2223/Ag) composite conductors heat treated without any additional rolling or pressing (beyond fabrication of the initial composite) has revealed that significant texturing of the Bi-2223 grains occurs as the Bi-2223 formation reaction takes place. During heat treatment, Bi-2223 is produced via a reaction between Bi-2212 and second phases in the core of the composite. As the Bi-2223 forms, it develops texture by what appears to be a grain growth mechanism. These concurrent processes ultimately result in a well-textured, single-phase conductor even when no additional rolling or pressing is done to the initial composite. This observation raises important questions about the relative contributions of the heat treatment and deformation steps to texture development during conventional oxide-powder-in-tube processing of Bi-2223/Ag composite conductors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2903-2905 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Grain orientations and grain boundary misorientations in high-Jc, powder-in-tube (PIT) (Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) were determined using electron backscatter Kikuchi diffraction and x-ray microdiffraction. Data collected from over 113 spatially correlated grains, resulting in 227 grain boundaries, show that over 40% of the boundaries are Σ1 or small angle (less than 15°). In addition, 8% of the boundaries are within the Brandon criterion for CSLs (sigma larger than 1 and less than 50). Grain boundary "texture maps'' derived from the electron microscope image and orientation data reveal the presence of percolative paths between low energy boundaries.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2277-2279 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Multifilamentary high-temperature superconductor (HTS) composite conductors have been developed for alternating current (ac) applications. A twisted HTS conductor containing the Bi-2223 phase fabricated using a modified powder-in-tube technique is reported. Transport critical current densities of 13 800 and 10 900 A/cm 2 (77 K, self-field, 1 μV/cm) have been achieved for twisted tape and wire conductors with twist pitches of 3.7 and 3.6 mm, respectively. These conductors are strongly linked and are thus suitable for use in ac applications. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Studies in Europe have reported a reduced prevalence of allergy in farmers' children. We aimed to determine if there is a similar reduction in allergy among New Zealand farm children.Methods: Two hundred and ninety-three children participated (60%) aged 7–10 years, from selected schools in small towns and the surrounding rural area . Skin prick tests (SPT) to eight common allergens were performed. Parents completed questionnaires about allergic and infectious diseases, place of residence, exposure to animals, and diet, and they provided dust from the living-room floor. Endotoxin was measured using an Limulus amoebocyte lysate (LAL) assay and Der p 1 using enzyme-linked immunoassay (ELISA).Results: Current farm abode was found to increase the risk of having symptoms associated with allergy, but not SPT positivity. Independent inverse associations were found for early-life exposures: at least weekly consumption of yoghurt with hayfever (odds ratio (OR) = 0.3, 95% confidence intervals (CI) 0.1–0.7) and allergic rhinitis (OR = 0.3, 95% CI 0.2–0.7); any unpasteurized milk consumption with atopic eczema/dermatitis syndrome (AEDS) (OR = 0.2, 95% CI 0.1–0.8); cats inside or outside with hayfever (OR = 0.4, 95% CI 0.1–1.0) and AEDS (OR = 0.4, 95% CI 0.2–0.8); dogs inside or outside with asthma (OR = 0.4, 95% CI 0.2–0.8); and pigs with SPT positivity (OR = 0.2, 95% CI 0.1–0.9).Conclusions: Despite finding a protective effect of early-life animal exposures, we found a greater prevalence of allergic disease on farms.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Melanin-concentrating hormone (MCH) is implicated in the control of a number of hormonal axes including the hypothalamic-pituitary adrenal (HPA) axis. Previous studies have shown that there is evidence for both a stimulatory and an inhibitory action on the HPA axis; therefore, we attempted to further characterize the effects of MCH on this axis. Intracerebroventricular injection of MCH increased circulating adrenocorticotropic hormone (ACTH) at 10 min post injection. Injection of MCH directly into the paraventricular nucleus (PVN) was found to increase both circulating ACTH and corticosterone 10 min after injection. Additionally, MCH was found to increase corticotropin-releasing factor (CRF) release from hypothalamic explants, and this effect was abolished by the specific SLC-1 antagonist SB-568849. Neuropeptide EI, a peptide from the same precursor as MCH was also found to increase CRF release from explants. These results suggest that MCH has a stimulatory role in the HPA axis via SLC-1, and that MCH exerts its effects predominantly through the PVN CRF neuronal populations
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Scandinavian journal of medicine & science in sports 15 (2005), S. 0 
    ISSN: 1600-0838
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Sports Science
    Notes: Chronic, painful conditions affecting tendons, frequently known as tendinopathy, are very common types of sporting injury. The tendon extracellular matrix is substantially altered in tendinopathy, and these changes are thought to precede and underlie the clinical condition. The tendon cell response to repeated minor injuries or “overuse” is thought to be a major factor in the development of tendinopathy. Changes in matrix turnover may also be effected by the cellular response to physical load, altering the balance of matrix turnover and changing the structure and composition of the tendon. Matrix turnover is relatively high in tendons exposed to high mechanical demands, such as the supraspinatus and Achilles, and this is thought to represent either a repair or tissue maintenance function. Metalloproteinases are a large family of enzymes capable of degrading all of the tendon matrix components, and these are thought to play a major role in the degradation of matrix during development, adaptation and repair. It is proposed that some metalloproteinase enzymes are required for the health of the tendon, and others may be damaging, leading to degeneration of the tissue. Further research is required to investigate how these enzyme activities are regulated in tendon and altered in tendinopathy. A profile of all the metalloproteinases expressed and active in healthy and degenerate tendon is required and may lead to the development of new drug therapies for these common and debilitating sports injuries.
    Type of Medium: Electronic Resource
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