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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 48 (1979), S. 365-383 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Gramicidin-doped asymmetric bilayers made by the Montal-Mueller method exhibited an asymmetric current-voltage relationship. The asymmetric conductance was shown to be the product of two components, a rectifying single-channel conductance and an asymmetric voltage dependence of the reaction which leads to the conducting channel. The single-channel conductance was asymmetric in both asymmetric bilayers made of charged lipids and asymmetric bilayers made only of neutral lipids. The single-channel asymmetry decreased with increasing ion concentration. From the comparison of the singlechannel conductance in symmetric and asymmetric bilayers and the dependence of the asymmetry on the solution ion concentrations, it was concluded that (1) the rate of ion entry into the channel is dependent on the lipid composition of the membrane and is asymmetric in asymmetric bilayers; (2) the entry step is rate determining at low ion concentrations; and (3) at higher ion concentrations the rate-determining step is the translocation across the main barrier in the membrane; and this translocation appears insensitive to lipid asymmetry.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 48 (1979), S. 385-401 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The asymmetric current-voltage relationship of gramicidin-doped asymmetric bilayers made by the Montal-Mueller technique was investigated in current relaxation experiments. It was shown that, in addition to the contribution of the asymmetric single channel conductance to the asymmetry of the steady-state current-voltage relationship, there is an asymmetric voltage dependence of the step which leads to the formation of the conducting channel. This asymmetric voltage dependence could be simulated in a model assuming a membrane-internal electrical potential drop or an equivalent potential, called asymmetry potential, which could be compensated by externally applying an offset potential. Significant asymmetry potentials were found in asymmetric bilayers made of charged lipids or only of neutral lipids. The asymmetry potential, was dependent on the salt composition in the aqueous phase. The factors responsible for the asymmetry potential do not appear to be of electrostatic origin. Several lines of evidence suggest that the dimerization step which leads to the conducting ion channel may be a complex series of reactions which are influenced by one or more membrane structural properties not yet characterized, in addition to the effects of the externally applied electric field.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 55 (1990), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Concentrates of fresh, ripe Spanish loquat fruit were analyzed by HRGC, HRGC-MS and HRGC-FTIR. In total, 80 aroma substances were identified, of which 72 are reported for the first time as loquat fruit constituents. The major part of volatiles comprised alcohols and carbonyls. Quantitative HRGC revealed hexanal (2.4 mg/kg fruit pulp), (E)-2-hexenal (1.8 mg/kg) and benzaldehyde (0.7 mg/kg) as major aroma compounds.
    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 75 (1994), S. 1843-1845 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Three-terminal YBa2Cu3O7−δ thin film devices based on a parallel array of grain boundary Josephson junctions were fabricated. The multiloop superconducting device is controlled by the magnetic field generated by a current Ictrl, which modulates the critical current Ic through the Josephson junction array. For these devices a current gain ranging between 2 at 77 K and 5 at 30 K was obtained. The spatial homogeneity of the device properties was studied by low-temperature scanning electron microscopy and by the determination of the supercurrent correlation function. Comparing the measured and the theoretically expected supercurrent correlation function shows that the device characteristics agree well with those expected from the device geometry.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An ion beam facility for high-intensity beams of highly charged ions in the energy range between 1 and 200 keV/u has been funded and will be installed in 1992 at the Institut für Kernphysik, Frankfurt am Main, Germany. The facility is based on a 14.6 GHz ECR ion source and a variable-energy RFQ as postaccelerator. The facility is intended for atomic-physics and materials research.
    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. 2289-2291 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The critical current Ic of YBa2Cu3O7−δ bicrystal grain boundary Josephson junctions (GBJs) have been measured in high magnetic fields up to B=12 T. Even at the highest applied magnetic fields, Ic varied periodically with varying magnetic field. By comparing the envelope of the measured Ic(B) dependencies to model calculations we obtain information on the spatial distribution of the supercurrent density jc on a length scale down to below 1 nm. Our analysis gives clear evidence that jc has spatial inhomogeneities on all length scales down to 1 nm with a probability distribution p(a) for the characteristic length scale a of the inhomogeneities. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1712-1714 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The planar gradiometer consists of a directly coupled magnetometer inductively coupled to the smaller loop of an asymmetric, two-loop flux transformer patterned in a single film of YBa2Cu3O7−x. The coupling is adjusted mechanically to balance the gradiometer to about 1 part in 3000 with respect to fields perpendicular to its plane. The baseline is 48 mm and the intrinsic balance with respect to in-plane fields about 1 part in 1400. When a magnetic field is applied solely to the magnetometer, its sensitivity is reduced by only 5% by the presence of the flux transformer. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1010-1012 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated Josephson vortex-flow transistors (JVFTs) based on asymmetric parallel arrays of YBa2Cu3O7−δ bicrystal grain boundary junctions. The critical current Ic and the voltage V at fixed bias current Ib were measured as a function of the control current Ictrl through a control line inductively coupled to the array. For JVFTs with an asymmetric in-line geometry a high current gain g=∂Ic/∂Ictrll ranging between about 20 at 40 K and 14 at 70 K was achieved. This current gain is much higher than that obtained for symmetric devices and results from the self-field effect of the electrode currents. In contrast to the current gain the transresistance rm=∂V/∂Ictrl of the JVFTs could not be enhanced by an asymmetric device structure. The current-voltage characteristics of the asymmetric JVFTs show pronounced step-like structures caused by the self-field of the electrode currents. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3341-3343 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated La1.85Sr0.15CuO4−δ grain boundary Josephson junctions (GBJs) fabricated on [001] tilt SrTiO3 bicrystals with misorientation angles of 24° and 36.8°. The resistive transition and the current–voltage characteristics of the GBJs are found to be close to those predicted by the resistively shunted junction (RSJ) model. Their product of the critical current density, Jc, and the normal resistance times area ρn, scales proportional to about (Jc)q with q=0.5–0.6 similar to what is found for YBa2Cu3O7−δ GBJs. By analyzing Fiske resonances the Swihart velocity of the GBJs and the ab-plane London penetration depth of La1.85Sr0.15CuO4−δ are obtained to c¯=2.5×106 m/s and λL=200 nm at 4.2 K, respectively. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 341 (1980), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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