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  • 1
    ISSN: 1432-0428
    Keywords: Glucose transport ; human adipocytes ; photolabelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Human adipose cells are much less responsive to insulin stimulation of glucose transport activity than are rat adipocytes. To assess and characterize this difference, we have determined the rates of 3-O-methyl-D-glucose transport in human adipose cells and have compared these with the levels of glucose transporter 4 (GLUT4) assessed by using the bis-mannose photolabel, 2-N-4-(1-azi-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(D-mannos-4-yloxy)-2-propylamine, ATB-BMFA. The rates of 3-O-methyl-D-glucose transport and the cell-surface level of GLUT4 are very similar in the human and rat adipocyte in the basal state. The Vmax for 3-O-methyl-D-glucose transport in fully insulin-stimulated human adipose cells is 15-fold lower than in rat adipose cells. Photolabelling of GLUT4 suggests that this low transport activity is associated with a low GLUT4 abundance (39·104 sites/cell; 19.9·104 sites at the cell surface). The turnover number for human adipose cell GLUT4 (5.8·104 min−1) is similar to that observed for GLUT4 in rat adipose cells and the mouse cell line, 3T3L1. Since 50% of the GLUT4 is at the cell surface of both human and rat adipose cells in the fully insulin-stimulated state, an inefficient GLUT4 exocytosis process cannot account for the low transport activity. The intracellular retention process appears to have adapted to release, in the basal state, a greater proportion of the total-cellular pool of GLUT4 to the cell surface of the larger human adipocytes. These cell-surface transporters are presumably necessary to provide the basal metabolic needs of the adipocyte. As a consequence of this adaptation to cell size and surface area, the residual intracellular-reserve pool of GLUT4 that is available to respond to insulin is lower in the human than in the rat adipocyte.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Key words Glucose transport ; human adipocytes ; photolabelling.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Human adipose cells are much less responsive to insulin stimulation of glucose transport activity than are rat adipocytes. To assess and characterize this difference, we have determined the rates of 3-O-methyl-d-glucose transport in human adipose cells and have compared these with the levels of glucose transporter 4 (GLUT4) assessed by using the bis-mannose photolabel, 2-N-4-(1-azi-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(d-mannos-4-yloxy)-2-propylamine, ATB-BMPA. The rates of 3-O-methyl-d-glucose transport and the cell-surface level of GLUT4 are very similar in the human and rat adipocyte in the basal state. The Vmax for 3-O-methyl-d-glucose transport in fully insulin-stimulated human adipose cells is 15-fold lower than in rat adipose cells. Photolabelling of GLUT4 suggests that this low transport activity is associated with a low GLUT4 abundance (39 · 104 sites/cell; 19.9 · 104 sites at the cell surface). The turnover number for human adipose cell GLUT4 (5.8 · 104 min–1) is similar to that observed for GLUT4 in rat adipose cells and the mouse cell line, 3T3L1. Since 50 % of the GLUT4 is at the cell surface of both human and rat adipose cells in the fully insulin-stimulated state, an inefficient GLUT4 exocytosis process cannot account for the low transport activity. The intracellular retention process appears to have adapted to release, in the basal state, a greater proportion of the total-cellular pool of GLUT4 to the cell surface of the larger human adipocytes. These cell-surface transporters are presumably necessary to provide the basal metabolic needs of the adipocyte. As a consequence of this adaptation to cell size and surface area, the residual intracellular-reserve pool of GLUT4 that is available to respond to insulin is lower in the human than in the rat adipocyte. [Diabetologia (1995) 38: 661–666]
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 198 (1963), S. 798-799 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The tissues were fixed in osmium tetroxide-sucrose solution and embedded in 'Epon'. Sections were stained with alkaline lead solution3. In the early stages of fibrogenesis, extremely thin ( 50 A) beaded filaments appear in the vicinity of each fibroblast. These filaments seem to adhere to ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6213-6215 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Materials with a large capacity to dissipate mechanical energy are of interest for passive vibration damping. We have measured the zero-field damping capacity of the giant magnetostrictive terbium–dysprosium–iron compounds by quasistatic stress–strain hysteresis loops. The magnetization and strain of the samples were measured for increasing and decreasing compressive stresses, up to 50 MPa. The zero-field, room temperature damping capacity (ΔW/W) was calculated from the stress–strain loops and is plotted against maximum stress. The damping capacity maximum for the alloy with the nominal Terfenol-D composition occurs at 4.1 MPa with the value 1.75 which corresponds to Q−1=0.28. The damping is almost independent of stress in a multi-phase sample, (Tb0.6Dy0.4)Fe1.4, which contains both Laves phase and elemental rare earth. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recently it was discovered that composites of Terfenol-D alloys with an insulating binder produce very large magnetostrictions. Resistivities of these composites reach high values, making them attractive for high-frequency applications which require small eddy current losses. In this paper the magnetostriction, magnetization, and Young's moduli measurements made under constant magnetic field conditions and under constant flux conditions are reported. From these measurements, magnetomechanical coupling factors are calculated. The properties are compared to those of ordinary metallic Terfenol-D and nickel. Two different types of composites were investigated. In the first type the composite has an isotropic structure and in the second type, anisotropic. It is shown that the anisotropic type is more desirable since it possesses both higher magnetostriction and higher coupling factors. It is also clearly shown that the magnetization process for the anisotropic type can be explained by a 180° domain wall motion followed by a magnetization rotation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5733-5735 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nitrogenation process of the TbFe3 intermetallic compound was studied by heat treating the alloy between 573 and 873 K in a nitrogen atmosphere. The structural and magnetic properties of the nitrogenated samples were characterized by x-ray diffraction (XRD), Mössbauer spectroscopy, and magnetic measurements. The magnetic moments of the nitrogenated samples were found to be a function of the annealing temperature and showed a minimum for the sample heat treated at 673 K. The XRD pattern of this sample (673 K) showed that the Bragg peaks of the 1-3 phase had completely disappeared and were replaced by a broad maximum indicating a breakdown of the TbFe3 structure into an amorphous phase. The room-temperature Mössbauer spectrum of the same sample consisted almost entirely of a quadrupole-split doublet plus a small amount of α-Fe and TbFe3. This doublet split into a broad spectrum upon cooling which is typical of amorphous rare-earth–transition-metal compounds. For samples heat treated at higher temperatures, the amount of α-Fe and TbN phases gradually increased. This nitrogenation process is unlike that of R2Fe17. In this study, nitrogen atoms do not go into the interstitial sites. Instead, they create a ferromagnetic (TC≈215 K) amorphous phase of Tb, Fe, and N which is stable over a wide temperature range.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Rare-earth–iron alloys, R0.9Fe0.1, R0.72Fe0.28, and R0.42Fe0.58 (R=Tb0.6Dy0.4), containing the R/RFe2 eutectic composition were prepared by Bridgman and free-standing zone-melting techniques. Magnetization measurements were made in fields up to 800 kA/m between 55 and 300 K. A huge increase in magnetization below 210 K occurs as the R component becomes ordered. At low applied magnetic fields there is clear identification of both the ferromagnetic ordering temperature TC and the Néel spiral ordering temperature TN of R. (For Tb0.6Dy0.4, TC=165 K, TN=210 K.) Magnetization and magnetostriction measurements reveal very large magnetocrystalline anisotropies for both the R and the RFe2 components. Unexpectedly, at 77 K, were the rare-earth component of the eutectic system is ordered and the magnetostriction is large (λhγ(approximately-greater-than)0.6%), the magnetostriction is largest in the samples containing the largest amount of the RFe2 phase. Young's modulus measurements reveal the reduction in the stiffness with the addition of the softer rare earth to the stiff RFe2 compound.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6150-6152 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The elastic moduli of the highly magnetostrictive TbxDy1−x alloys (x=0.5, 0.6, and 0.67) were measured at 77 K under conditions of constant magnetic field and constant magnetic induction. From these values the magnetic contribution to the moduli (intrinsic ΔE effect) and magnetoelastic coupling factor k were calculated. For Young's moduli measured under constant flux density (magnetically blocked conditions), it was found that EB∼20 to 50 GPa. For measurements made while maintaining a constant magnetic field (magnetically free conditions), it was found that Young's moduli EH minima range from ∼3 to 5 GPa. Such large differences between EB and EH yield magnetoelastic coupling factors in excess of 0.9. Theoretical expressions of the magnetic contribution to the elastic compliance, (1/EH−1/EB), were derived using the single vector magnetization rotation model.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6216-6218 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature dependence of Young's modulus has been measured for a series of Tb1−xDyxZn pseudobinary compounds with x ranging from 0 to 1. From the sharp dips in the modulus vs temperature data, the reorientation transition temperatures have been determined, and the magnetic phase diagram deduced. Magnetization measurements taken on the same samples show less pronounced features at the corresponding temperatures. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5771-5773 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: From magnetization (M) and magnetostriction (λ) measurements as a function of magnetic field and stress, the temperatures of anisotropy compensation, Tm, for technologically important TbxDy1−x(Fe1−yTy)1.9 [T=Co,Mn (0.3≤x≤0.5) (0≤y≤0.3)] were determined. Measurements of M and λ encompassing Tm were made under compressive stresses from 8.8 to 36 MPa and for temperatures from −196 to +130 °C. In agreement with earlier measurements, Tm decreases with increasing Tb. Substitution of Mn for Fe for fixed x also decreases Tm. In contrast with these observations is the increase of the anisotropy compensation temperature with the replacement of Fe by small amounts of Co. In the cases of both (1) increasing Tb content and (2) increasing Co content, the Curie temperature TC increases, yielding, in general, a higher magnetic moment and saturation magnetostriction of these alloys. Thus, compensation at a given temperature may be obtained in an improved class of Laves phase compounds, R(1)xR(2)1−x(Fe1−yCoy)2, where rare earths R(1) and R(2) are, for example, Tb and Dy.
    Type of Medium: Electronic Resource
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