ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (98)
  • Other Sources
  • 74.72.Bk  (50)
  • mitochondria  (48)
  • Springer  (98)
  • American Geophysical Union
  • American Institute of Physics (AIP)
  • American Physical Society
  • Blackwell Publishing Ltd
  • Institute of Physics
  • Oxford University Press
  • 1995-1999  (98)
  • Physics  (98)
  • Natural Sciences in General
  • Electrical Engineering, Measurement and Control Technology
Collection
  • Articles  (98)
  • Other Sources
Source
Keywords
Publisher
  • Springer  (98)
  • American Geophysical Union
  • American Institute of Physics (AIP)
  • American Physical Society
  • Blackwell Publishing Ltd
    • +
Years
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Low-temperature (T〈180 K) relaxation processes and possible “electronic phase separation” in RBa2Cu3O6+x (R=Y, Tm, Lu) single crystals (1996)
    Springer
    JETP letters 63 (1996), S. 830-834 
    Details
    ISSN: 1090-6487
    Keywords: 74.72.Bk ; 74.72.Jt ; 64.75.+g ; 77.22.Gm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Low-temperature (120–180 K) relaxational effects are observed in oxygen-deficient RBa2Cu3O6+x (R=Y, Tm, Lu) single crystals. Isothermal holding of the crystals after rapid cooling increases their resistance. The characteristic times and the activation energy of the relaxation process, E a ≈0.46 eV, are determined. The possible relation between the observed effects and the appearance of “electronic phase separation” is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567098
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Shape of the Cu(2) NQR spectra in YBa2Cu3O7, TmBa2Cu3O7 and TmBa2Cu4O8 (1997)
    Springer
    JETP letters 66 (1997), S. 624-629 
    Details
    ISSN: 1090-6487
    Keywords: 76.60.Gv ; 74.72.Bk ; 74.72.Yg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a study of shape of the Cu(2) NQR spectra in YBa2Cu3O7, TmBa2Cum3O7, and TmBa2Cu4O8 compounds at temperatures of 4.2–300 K. The results of the quantitative analysis lead us to conclude that the shape of the Cu(2) NQR spectra in all the samples studied can be described in the framework of the “motional narrowing” model, which implies that the Cu(2) nucleus possesses two different NQR frequencies between which it can rapidly jump. The difference in frequencies seems to be related to the charge-stripe correlations in CuO2 planes resulting in a dynamical modulation of the electric field gradients at the Cu(2) nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567612
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Linear low-temperature dependence of the surface impedance of a Ba0.6K0.4BiO3 single crystal (1996)
    Springer
    JETP letters 64 (1996), S. 832-838 
    Details
    ISSN: 1090-6487
    Keywords: 84.37.+q ; 74.72.Yg ; 74.72.Bk ; 74.72.Hs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The temperature dependences of the real part R s and the imaginary part X s of the surface impedance Z s =R s +iX s of the superconductor Ba0.6K0.4BiO3 (T c ≃30 K) are measured at a frequency of 9.4 GHz. Its temperature dependence Z s (T) and that of the complex conductivity σ s (T) can be described on the basis of a two-fluid model under two assumptions: The density of superconducting carriers increases linearly, and the relaxation time increases as a power law (∝1/T 5), with decreasing temperature T〈T c . This model also describes well the curves Z s (T) and σs (T) recently measured for YBa2Cu3O6.95 and Bi2Sr2CaCu2O8 single crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567255
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Anisotropy of the superconducting properties of YBa2Cu3O7−x single crystals with reduced oxygen content (1998)
    Springer
    JETP letters 68 (1998), S. 332-337 
    Details
    ISSN: 1090-6487
    Keywords: 74.72.Bk ; 74.25.Fy ; 74.62.Bf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In an investigation of the resistivity anisotropy of YBa2Cu3O7−x single crystals with suboptimal oxygen content it is observed that the superconducting transition for the component ρc of the resistivity tensor is shifted to lower temperatures with respect to the transition for the component ρab. A similar shift is also observed for the transition in the temperature dependence of the dynamic magnetic susceptibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567869
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Subharmonic Shapiro steps and noise in high-T c superconductor Josephson junctions (1998)
    Springer
    JETP letters 68 (1998), S. 454-459 
    Details
    ISSN: 1090-6487
    Keywords: 74.50.+r ; 74.25.Fy ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An experimental investigation is made of the subharmonic Shapiro steps observed on the I-V curves of high-T c superconductor Josephson junctions and on the bias-voltage dependences of the rf noise and detector response when the junctions are subjected to external submillimeter radiation. Structures of this type are ordinarily described by a nonsinusoidal current-phase relation, which is why subharmonic steps appear. Numerical modeling of the processes occurring in a Josephson junction by means of a simple current-phase relation, as in the case of an SNS junction, gives good agreement with experiment. The width of the characteristic Josephson generation line of the junction was estimated on the basis of the noise dependences and the selective detector response. The width can be explained by taking into account the shot noise of the tunneling component of the conductivity. A model of the conductivity of a high-T c superconductor Josephson junction, consisting of a tunnel junction with microshorts possessing metallic conductivity, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567889
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A new optical method for measuring the electron-phonon interaction parameter λ〈Ω2〉 using the spectral dependence of the relaxation rate (1999)
    Springer
    JETP letters 70 (1999), S. 329-333 
    Details
    ISSN: 1090-6487
    Keywords: 78.47.+p ; 63.20.Kr ; 74.25.Jb ; 74.25.Kc ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spectral dependence of the electron-phonon relaxation rate γe−ph(ℏω) in metals is studied in pump-supercontinuum-probe (PSCP) experiments with femtosecond time resolution. Investigation of this spectral dependence, which exhibits a substantial slowing of the relaxation rate γe−ph(ℏω) near the Fermi level E F , using the parametrization γe−ph(ℏω)∝λ〈Ω2〉 (ℏω−E F )2 makes it possible to determine directly the electron-phonon interaction parameter λ〈Ω2〉. The parameter λ〈Ω2〉 for YBa2Cu3O7−δ is analyzed using this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.568175
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Stripe motion in CuO2 planes of Y1−x Pr x Ba2Cu3O7 as observed from the Cu(2) quadrupole resonance (1997)
    Springer
    JETP letters 65 (1997), S. 821-827 
    Details
    ISSN: 1090-6487
    Keywords: 61.72.Hh ; 74.72.Bk ; 74.80.−g ; 76.60.Gv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The NQR spectra of copper in the compounds YBa2Cu3O7, TmBa2Cu3O7, and Y0.9Pr0.1Ba2Cu3O7 at temperatures of 4.2–200 K are investigated by a pulsed NQR technique at frequencies of 28–33 MHz. Quantitative analysis of the spectra shows that the shape of the “plane” Cu(2) spectra is well described by using a model of 1D correlations of the charge and spin distribution in the CuO2 planes (stripe correlations). In the undoped superconductors the charge-spin stripe structure moves fast in the CuO2 planes, but doping the YBa2Cu3O7 lattice with praseodymium slows this motion down.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567452
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Nature of the microwave response of a YBaCuO Josephson junction on a bicrystalline substrate (1996)
    Springer
    JETP letters 64 (1996), S. 454-459 
    Details
    ISSN: 1090-6487
    Keywords: 74.60.+r ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The response of YBaCuO Josephson junctions on a bicrystalline substrate to the action of microwave radiation is found to contain, besides the Josephson response, a contribution associated with the tunneling of quasiparticles through channels formed by localized states in the region of the Josephson junction. It is shown that this contribution is associated with an increase in the conduction through these channels under the action of the radiation on the junction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567219
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Anomalies of the electronic spin-lattice relaxation of Gd3+ in YBa2Cu4O8 and YBa2Cu3O6+x near 200 K (1999)
    Springer
    JETP letters 69 (1999), S. 610-615 
    Details
    ISSN: 1090-6487
    Keywords: 74.72.Bk ; 76.60.Es
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A sharp kink in the temperature dependence of the electronic spin-lattice relaxation rate near 200 K was found in the high-temperature superconductors YBa2Cu4O8 and YBa2Cu3O6+x . The effect is correlated with opening of a spin gap and microscopic phase separation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567968
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Characteristic features of the temperature dependence of the surface impedance of YBa2Cu3O6.95 single crystals (1997)
    Springer
    JETP letters 65 (1997), S. 938-944 
    Details
    ISSN: 1090-6487
    Keywords: 74.25.Nf ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The real and imaginary parts of the surface impedance Z s =R s +iX s of YBa2Cu3O6.95 single crystals are measured at a frequency ω/π=9.4 GHz. The quantities R s (T) and X s (T) are linear functions of temperature for T〈0.3T c (T c =93.5 K). A maximum of R s (T) and a plateau of X s (T) are observed in the interval 35〈T〈65 K. Our experimental data, just as all recent measurements of R s (T) in YBa2Cu3O6.95 single crystals in the temperature range 0〈T〈1.3T c , are described well in a two-fluid model which assumes electron-phonon scattering of quasiparticles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567453
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Spin susceptibility of neutron-irradiation-disordered YBa2Cu3O6.9 in the normal and superconducting states (1998)
    Springer
    JETP letters 67 (1998), S. 182-188 
    Details
    ISSN: 1090-6487
    Keywords: 61.80.Hg ; 76.60.Es ; 74.72.Bk ; 74.25.Nf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spin-spin relaxation rate 63 T 2 −1 of 63Cu nuclei in CuO2 layers is measured in the normal and superconducting states of the compound YBa2Cu3O6.9 (T c onset =94 K) subjected to radiation-induced disordering by a fast-neutron flux Φ to T c onset =68 K (Φ=7×1018 cm−2) and T c onset 〈4 K (Φ=12×1018 cm−2). It is found that as the structural disorder increases, the contribution of the indirect spin-spin interaction 63 T 2G −1 , which is related to the value of the spin susceptibility at the boundary of the Brillouin zone of the copper planes χs(q={π/a; π/a}), decreases slightly at the transition to the superconducting state for the initial sample and remains unchanged for the weakly disordered sample. This behavior of the short-wavelength contribution to the spin susceptibility attests to the stability of the x 2−y 2 symmetry of the energy gap against structural disorder, in accordance with proposed theoretical models of Cooper pairing for high-T c cuprates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567648
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Antiferromagnetism in hydrated 123 compounds (1999)
    Springer
    JETP letters 69 (1999), S. 792-797 
    Details
    ISSN: 1090-6487
    Keywords: 74.72.Bk ; 74.25.Ha ; 75.50.Gg ; 76.60.Gv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Copper nuclear quadrupole resonance and zero-field nuclear magnetic resonance (ZFNMR) studies of YBa2Cu3O6.5 show that a magnetic phase appears in underdoped 123 superconductors treated in ambient moist air. The studies give convincing evidence that the “empty” CuO chains play the role of easy water insertion channels. The reaction occurs first in ordered regions of the crystallites. The final product of the reaction is a nonsuperconducting antiferromagnetic compound characterized by at least two types of magnetically ordered copper ions, with ZFNMR spectra in the frequency ranges 46–96 and 96–135 MHz, respectively. Even for powder samples fixed in an epoxy resin, this reaction is found to have partially occurred after a few years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.568092
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Effect of asymmetry of CuO2 layers in copper oxides on the anomalous neutron scattering near T c (1999)
    Springer
    JETP letters 69 (1999), S. 392-397 
    Details
    ISSN: 1090-6487
    Keywords: 74.72.Bk ; 61.12.Ex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Reasons for critical magnetic scattering of neutrons near T c in copper oxides with CuO2 layers whose nearest environment has no “up-down” symmetry are discussed. The intracrystalline electric field, which threads the CuO2 planes on account of the asymmetry, induces coupling between the spin and momentum of the current carriers. This coupling is shown to result in a manifestation of virtual Cooper pairs in the imaginary part of the spin susceptibility. Thus spin density fluctuations as well as current fluctuations should participate in the scattering. A way of experimentally distinguishing between the two mechanisms is pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.568040
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Anomalous behavior of the structural parameters of YBa2Cu4O8 single crystals at the transition to the superconducting state (1997)
    Springer
    JETP letters 66 (1997), S. 534-539 
    Details
    ISSN: 1090-6487
    Keywords: 61.50.Ks ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High-precision x-ray crystallographic studies of YBa2Cu4O8 single crystals (T c =70 K) are performed at eight temperatures in the interval 20–295 K. It is found that a number of structural parameters exhibit anomalous behavior near the superconducting transition of the crystal. A characteristic effect near the phase transition is the displacement of the O1 bridge atom that joins the Cu1 atom of the cuprate chain to the Cu2 atom of the cuprate plane. The shift of this oxygen toward the Cu2 atom is indicative of a change in the Cu2-O1 chemical bond and of charge transfer to the cuprate plane in the process of the transition of the crystal to the superconducting state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567560
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Theory of the pseudogap in the elementary excitation spectrum of the normal phase of bilayer cuprates (1997)
    Springer
    JETP letters 66 (1997), S. 569-574 
    Details
    ISSN: 1090-6487
    Keywords: 74.25.Jb ; 74.25.Gz ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Solutions of the integral equations for the pseudogap in the elementary excitation spectrum of current carriers in bilayer cuprates are found. In the general case, the pseudogap possesses s + id symmetry, where the s component is determined by the interaction of holes via the phonon field and the d component is due to the superexchange interaction of the copper spins and the Coulomb-repulsion screened holes. The s and d components exhibit different temperature dependences. This fact enabled us to explain the characteristic features of the temperature behavior of the normal-phase spin susceptibility of lightly doped cuprates, specifically, for the compound YBa2Cu4O8 in the entire temperature interval T〉T c . The wave-number dependence of the pseudogap agrees with the photoemission data for Bi2Sr2CaCu2O8+y .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567547
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Comparative studies of the NMR of thulium in Tm123 and Tm124 compounds: Evidence for structural and electronic phase separation (1996)
    Springer
    JETP letters 64 (1996), S. 398-403 
    Details
    ISSN: 1090-6487
    Keywords: 61.72.Hh ; 74.72.Bk ; 74.80.Bj ; 76.60.Lz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The nuclear magnetic relaxation of 169Tm in TmBa2Cu3O6+x (x=0.1–1.0, Δ x=0.1) and TmBa2Cu4O8 is studied at temperatures below 5 K. In all the samples, the Tm spin-lattice relaxation proceeds via intrinsic paramagnetic centers (PCs) like Cu2+ or copper-oxygen spin-polarized clusters. The experimental data for TmBa2Cu3O6+x support the idea of the structural (chemical) micro-phase separation in oxygen-deficient 123 compounds. Apparently, the samples with x⩾0.4 contain hole-poor nonsuperconducting regions, enriched with PCs, and hole-rich (PC-poor) superconducting regions. The volume fraction f n of the PC-rich phase reaches a maximum value of 0.85 at x=0.4 and decreases monotonically with increasing x (f n=0.5, 0.3, and 0.25 at x=0.5, 0.6, and 0.7, respectively). The Tm spin-lattice relaxation in the underdoped TmBa2Cu4O8 compound indicates that this sample, in contrast to oxygen-deficient TmBa2Cu3O6+x , has a homogeneous composition. However, the Tm spin-spin relaxation measurements reveal two sorts of the Tm nuclear spins in Tm124, having different NMR spectra and different relaxation times T 2. The latter result is evidence of electronic phase separation in CuO2 phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567210
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Commensurability oscillations and a new phase transition in YBa2Cu3Oy single crystals (1999)
    Springer
    JETP letters 69 (1999), S. 881-886 
    Details
    ISSN: 1090-6487
    Keywords: 74.72.Bk ; 75.60.Ej ; 74.25.Ha
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Magnetization oscillations due to the commensurability of the vortex and crystal lattice periods in YBa2Cu3Oy (y=6.97±0.02) single crystals are investigated using a high angular resolution magnetometer. A sharp peak in the temperature dependence of the oscillation amplitude as well as other features in the behavior of the oscillation amplitude and of the irreversible magnetization are observed at T f ∼60 K. It is inferred that T f is the temperature of a transition of the solid vortex state to a smectic phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.568106
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Transport and Cu NMR studies of charge and spin dynamics in PrBa2Cu4O8 (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 437-442 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk ; 72.15.−v ; 76.60.−k
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The charge and spin dynamics in PrBa2Cu4O8 are investigated by means of transport and Cu NMR measurements. The magnetoresistance was found to be very small at high temperatures and increase rapidly with decreasing temperature below ∼100 K, which may be ascribed to the dimensional crossover from one to two dimensions in the charge transport in the CuO double chains. While the NMR signal from the chain Cu sites persists down to 4.2 K without any appreciable line broadening, the signal from the planar Ce sites disappears below ∼250 K indicating the long-range antiferromagnetic order of plane Cu moments. This is consistent with the view of metallic conduction along the quasi one-dimensional CuO chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768425
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    On atoms charge states in RBa2Cu3Ox high-temperature superconductors (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 359-364 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The distribution of charge states of all atoms in the unit cell of RBa2Cu3Ox; x=6,7 (R = Yb, Er, Ho, Y, Gd, Eu, Sm, Nd, Pr) is determined on the basis of comparison of the theoretical calculated electric field gradient tensor and existing experimental data. The variation of the charge states of the atoms as a function of the ionic radius is analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768412
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Dynamical structural instability in YBa2Cu3O6.6 (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 837-842 
    Details
    ISSN: 1573-7357
    Keywords: 74.72−h ; 74.72.Bk ; 87.64.Bx ; 74.25.Kc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have performed inelastic neutron scattering and total neutron scattering experiments on the under-doped superconductor YBa2Cu3O6.6. We have found that the dynamical structure and the local structure concerned about the CuO2 plane has an anomalous temperature dependence at Tc (=57K) and well above Tc (TSG∼150K), which may be explained by a spin-gap opening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768487
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Influence of micro-structure in the low temperature critical currents of YBa2Cu3O7−δ thin films (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1017-1022 
    Details
    ISSN: 1573-7357
    Keywords: 74.60Jg ; 74.72.Bk ; 74.76.Bz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Epitaxial YBa2Cu3O7−δ films nucleate in c-axis oriented single-crystalline islands. The surface of the single-crystalline SrTiO3 substrates exhibit steps of one third of the YBa2Cu3O7−δ c-axis. These steps generate a mismatch in the island boundaries between the CuO2 superconducting blocks. We show that these defect regions are strong candidates for being the pinning centers responsible for the large critical currents observed in Laser Ablated and Sputtered thin films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768516
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Electronic transport and specific heat of Ca-doped YBa2Cu3Ox-single crystals (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 909-914 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Bt ; 74.25.Fy ; 74.62.Dk ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the anisotropic electrical resistivity, the Hall Effect, and the specific heat anomaly at Tc of Ca-doped YBa2Cu3Ox single crystals of various Ca and O contents are presented. The transport properties are discussed in terms of charge and spin separated quasiparticles and confirm that by doping Ca onto Y sites the hole concentration, nh, can be extended beyond the value achieved with O-doping alone at x=7.0. The jump in the specific heat at Tc which increases monotonously with x up to x=7.0 in Ca-free crystals displays a maximum in highly oxygenated Ca-doped crystals. This maximum, however, is displaced from the Tc(nh) maximum to higher values of nh, consistent with the model of induced superconductivity in the CuO chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768498
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Cu-O bond-stretching vibrations in YBa2Cu3O7 studied by inelastic neutron scattering (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 807-812 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk ; 74.25.Ke ; 63.20.Kr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Inelastic neutron experiments confirm the previously reported anomalous nature of the planar oxygen bond-stretching vibrations and furnish further details. It is shown that the frequency of the linear breathing mode is renormalized by 5 THz compared to insulating YBa2Cu3O6. Studies of the Cu1-apical O bond-stretching vibrations demonstrate that frequencies, line-widths and phonon intensities can well be understood within the framework of a harmonic lattice dynamical model. This rules out predictions of a double well potential and strong anharmonitity for this type of vibration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768482
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Ion-channeling studies of lattice anomalies well aboveT c in YBa2CU3O7−y (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 831-836 
    Details
    ISSN: 1573-7357
    Keywords: 61.85.+p ; 74.20.Mn ; 74.25.Kc ; 74.62. Bf ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Backscattering yields in the 〈001〉 axial channeling mode using D+ ions have been measured for YBa2Cu3O7−y single crystals with Tc=59K. 68K and 91K at temperatures between 40K and 295K. In 60 K-class YBa2Cu3O7−y with significant anomalies associated with the spin gap, it is found that the channeling anomalies are observed at 130–140 K(Tpa) in addition to anomalies at Tc. The channeling anomalies at Tc follow to the shift of Tc, suggesting the phonon anomalies induced by the superconducting-gap opening. On the other hand, Tpa is found to be almost unchanged for varying Tc, although Tpa appears near the temperature where the spin gap is opened. This leads a question whether the channeling anomalies at Tpa is directly related to the phonon anomalies induced by the spin-gap opening. The existence of lattice instability is suggested as one of possible explanations for the anomalies at Tpa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768486
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Transport results from untwinned YBCO: Washboard frequency of the vortex lattice, and the quasiparticle mean free path (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 877-886 
    Details
    ISSN: 1573-7357
    Keywords: 74.60.Ge ; 72.15.Lh ; 74.72.−h ; 72.15.Gd ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The “washboard frequency” ω of the moving vortex lattice in untwinned YBa2 Cu3 O6.93 may be observed through mode-locking to an externally applied ac current of frequency ωext. The interference between ω and ωext results in jumps in the dc current-voltage characteristics when ω and ωext are harmonically related1. The interference effect disappears in the vortex liquid state. The Hall conductivity σxy below Tc in YBCO contains contributions2 from a positive quasiparticle (qp) term (∼H) and a negative vortex term (∼1/H). The qp term is surprisingly large well below Tc and implies a large gap anisotropy and a long qp mean free path (mfp). The thermal Hall effect3 κxy is closely related to the qp σxy; κxy is produced by asymmetric scattering of qp by pinned vortices. The qp mfp at H = 0, extracted from σxy and extended to low T by κxy, increases remarkably from 90 Å at Tc to more than 0.5μm at 22 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768493
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Raman scattering by electronic excitations in semiconductors and in highT c superconductors (1995)
    Springer
    Journal of low temperature physics 99 (1995), S. 205-221 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Gz ; 74.72.Bk ; 78.30.Er ; 71.25.−s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Raman scattering by electronic excitations in normal and superconducting metals with complex Fermi surfaces is discussed. The theoretical results are applied to the case of high Tc superconductors. The possible implications of measurements of this scattering concerning the symmetry of the gap function is dealt with.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00752289
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Photoinduced enhancement of the Josephson effect in YBaCuO grain boundary junctions (1997)
    Springer
    Journal of low temperature physics 106 (1997), S. 255-264 
    Details
    ISSN: 1573-7357
    Keywords: 73.50.Pz ; 74.50.+r ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experiments of persistent photoinduced enhancement of the Josephson effect in YBaCuO junctions are reviewed in this paper. These experiments show that the critical current and the conductivity of these Josephson junctions can be increased after illumination. This effect is due to photodoping of the oxygen depleted region in the weak link.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399623
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    The influence of external bias voltage on electrical properties of YBa2Cu3O7−x /metal point contact interface (1997)
    Springer
    Journal of low temperature physics 106 (1997), S. 277-283 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk ; 74.50.+r ; 74.80.Fp ; 73.40.Cg ; 73.40.Gk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated a change of electrical properties of YBa2Cu3O7−δ/metal point contact immediately after its preparation depending on time, temperature as well as external bias voltage. The increase of the point contact differential resistance in time was experimentally observed at temperature above 200 K even if no external bias voltage was applied. The low external bias voltage considerably influences the time increase of the differential resistance indicating an important role of oxygen diffusion. It is shown on differential characteristics that for Au, In the parameters of tunneling barrier such as the average height and width are constant in time whereas for Al, Pb an evolution of the tunneling barrier was observed because of oxidation of Al and Pb. Applying of higher bias voltage (up to 1 V) enables the transport of oxygen even below 200 K (down to 4.2 K) and changes the electrical properties of YBCO/metal point contact interface. The differential characteristics change their behaviour from that typical for NIS contact with strong tunneling barrier to NS contact with a high transparency of the interface. All the above changes are reversible upon changing the bias voltage polarity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399626
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Experimental study of the intergranular weak link structures YBa2Cu3O7−x with the help of magnetization measurements (1997)
    Springer
    Journal of low temperature physics 106 (1997), S. 447-452 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract AC and DC virgin magnetizations of sintered YBa2Cu3O7−x samples have been measured in dependence of the sintering temperature. The samples were prepared by solid state reaction of stoichiometric decarbonated mixture of Y2O3, BaCO3 and CuO components. Magnetization curves were measured at 77K in the range of magnetic field (10−1−2×104 Am −1). The temperature of sintering was being changed in the range 910°C up to 950°C. In the range of weak magnetization fields the magnetization curves are affected by properties of the intergranular medium — the intergranular weak links. The parameters H 1 w1 , H 2 w1 and H 1 g characterising the flux penetration into intergrain and intragrain medium were estimated from the magnetization measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399651
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    Granular nature and superconductive coupling of YBa2Cu3O7 polycrystals observed by microwave absorption measurements (1997)
    Springer
    Journal of low temperature physics 106 (1997), S. 469-474 
    Details
    ISSN: 1573-7357
    Keywords: 74.80.Bj ; 74.72.Bk ; 74.50.+r ; 78.70.Gq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The results of measurements of the H-modulated microwave absorption of of YBa2Cu3O7 ceramic in the transition temperature region and with fields in the range 0–10 kOe are presented. They give clear evidence of the weak-link inter-grain nature of the gross part of the dissipation and support the idea of stronger links, or microbridges of a more intrinsic species, involved in the high-field intra-grain absorption component. A semiquantitative analysis of the absorption process is suggested and applied to the derivative spectra in the T-swept form (at fixed external field). It allows to deduce information about Tc, the superconductive coupling, and the H- and T-dependences of the critical currents involved in the inter- and intra-grain regions. When applied to YBa2Cu3O7 powders, obtained by finely grinding a ceramic pellet, it gives also evidence of a generalized suppression of coupling induced by the grinding process
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399654
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    Upward curvature of the microwave surface resistance vs. field in YBCO films and the Clem's Rs model (1997)
    Springer
    Journal of low temperature physics 106 (1997), S. 487-492 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Nf ; 74.60.Ge ; 74.72.Bk ; 78.70.Gq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The recent experimental data by I. S. Ghosh et al. (1994) on microwave losses induced by flux motion in YBCO thin films are discussed, which seem to contradict a generalized use of the surface resistance model proposed by Coffey and Clem (1992) in the field range 0–8 Tesla. It is found that the necessary condition, in order to reproduce the upward curvature vs. field observed for B‖BMW‖ film surface, is to assume that the Campbell penetration depth is governed by a critical field dependence reminishent of the well known Bc∝(1−t)3/2 expression. Nevertheless, the experimental data for the perpendicular case B⊥BMW and the behaviours in very low fields for both orientations cannot be satisfactorily explained in this view. It is shown that the discrepancies may be rationalized in a quite natural way as due to losses in a network of Josephson junctions of an intrinsic species, located in the intragrain region of the film.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399657
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Anion channels of the inner membrane of mammalian and yeast mitochondria (1996)
    Springer
    Journal of bioenergetics and biomembranes 28 (1996), S. 125-130 
    Details
    ISSN: 1573-6881
    Keywords: Channel ; patch clamp ; mitochondria ; ClATP channels ; inner mitochondrial membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The inner membrane of yeast and mammalian mitochondria has been studiedin situ with a patch clamp electrode. Anion channels were found in both cases, although their behavior and regulation are different. In mammalian mitochondria, the principal channel is of around 100 pS conductance and opens mainly under depolarized membrane potentials. As no physiological compound able to alter its peculiar voltage dependence has yet been found, it is proposed that this channel may serve as a safeguard mechanism for recharging the mitochondrial membrane potential. Two other anion channels, each with a distinct conductance (one of approx. 45 pS, the second of at least a tenfold higher value) and kinetics are harbored in the yeast inner membrane. Matrix ATP was found to interact with both, but with a different mechanism. It is proposed that the 45 pS channel may be involved in the homeostatic mechanism of mitochondrial volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110642
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Steady-State Proton Translocation in Bovine Heart Mitochondrial bc 1 Complex Reconstituted into Liposomes (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 81-87 
    Details
    ISSN: 1573-6881
    Keywords: bc 1 complex ; mitochondria ; cytochromes ; transmembrane pH difference ; H+/e − ratio ; decoupling ; azide ; arachidonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The effect of different anions on the steady-state proton translocation in bovine bc 1 complex reconstituted in liposomes was studied. The H+/e − ratio for vectorial proton translocation is at the steady state definitely lower than that measured at level flow, (0.3 vs. 1.0). The presence of azide or arachidonate at micro- and submicromolar concentrations, respectively, gave a substantial reactivation of the proton pumping activity at the steady state, without any appreciable effect on respiration-dependent transmembrane pH difference. Addition of azide to turning-over bc 1 vesicles also caused a transition of b cytochromes toward oxidation. The results are discussed in terms of possible involvement of an acidic residue in the protonation of the semiquinone/quinol couple at the N side of the membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022467923837
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Nuclear Control of Respiratory Chain Expression in Mammalian Cells (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 109-119 
    Details
    ISSN: 1573-6881
    Keywords: ETS domain ; gene expression ; mammalian cells ; mitochondria ; nuclear respiratory factors ; oxidative phosphorylation ; regulation ; respiratory chain ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The majority of gene products required for mitochondrial respiratory function are encoded in the nuclear genome. These include most of the respiratory subunits and all of the proteins that regulate the mitochondrial genetic system. One approach to understanding nucleo-mitochondrial interactions in mammalian cells is to identify the nuclear transcription factors that are common to the expression of these gene products. This has led to the purification and molecular cloning of nuclear respiratory factors, NRF-1 and NRF-2. The DNA binding and transcriptional specificities of these proteins have implicated them in the expression of many respiratory subunits along with key components of the mitochondrial transcription, replication, and heme biosynthetic machinery. In addition, tissue-specific transcription factors have been linked to the coordinate synthesis of contractile proteins and muscle-specific respiratory subunits whereas other more ubiquitous factors may have a dual function in nuclear and mitochondrial gene activation. These findings provide a framework for further investigations of the nuclear genetic mechanisms that integrate the expression of the respiratory apparatus with that of other cellular systems during growth and development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022681828846
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Cardiolipin Remodeling in a Chinese Hamster Lung Fibroblast Cell Line Deficient in Oxidative Energy Production (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 291-298 
    Details
    ISSN: 1573-6881
    Keywords: Cardiolipin metabolism ; CCL16-B2 cells ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The metabolism of cardiolipin was investigated in a Chinese hamster lung fibroblast cell line CCL16-B2 deficient in oxidative energy metabolism and its parental cell line CCL16-B1. Mitochondrial enzyme activities involved in de novo cardiolipin biosynthesis were elevated in CCL16-B2 cells compared with CCL16-B1 cells, indicating initially an elevation in cardiolipin biosynthesis. Content of all phospholipids, including cardiolipin and its precursors, and high energy nucleotides were unaltered in CCL 16-B2 cells compared to CCL 16-B1 cells. When cells were incubated with [1,3-3H]glycerol for up to 4 h radioactivity incorporated into cardiolipin in CCL16-B2 cells did not differ compared with CCL16-B1 cells. In contrast, radioactivity incorporated into phosphatidylglycerol, the immediate precursor of cardiolipin, was elevated over 2-fold in CCL16-B2 cells compared with CCL16-B1 cells. Analysis of the fatty acid molecular species in cardiolipin revealed alterations in the level of unsaturated but not saturated fatty acids in B2 compared with B1 cells. In vivo cardiolipin remodeling, that is, the deacylation of cardiolipin to monolysocardiolipin followed by reacylation back to cardiolipin, with [1-14C]palmitate and [l-14C]oleate and in vitro mitochondrial phospholipid remodeling with [1-14C]linoleate were altered in CCL16-B2 cells compared to CCL16-B1 cells. Since both the appropriate content and molecular composition of cardiolipin is required for optimum mitochondrial oxidative phosphorylation, we suggest that the difference in CL molecular species composition observed in CCL16-B2 cells, mediated by alterations in in vivo cardiolipin remodeling, may be one of the underlying mechanisms for the reduction in oxidative energy production in CCL16-B2 cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022418328922
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    On the Structure and Gating Mechanism of the Mitochondrial Channel, VDAC (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 525-531 
    Details
    ISSN: 1573-6881
    Keywords: Porin ; ion channel ; mitochondria ; VDAC ; electron microscopy ; sequence analysis ; β-barrel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract There is considerable evidence that the voltage-gated mitochondrial channel VDAC forms a β-barrel pore. Inferences about the number and tilt of β-strands can be drawn from comparisons with bacterial β-barrel pores whose structures have been determined by x-ray crystallography. A structural model for VDAC is proposed (based on sequence analysis and electron crystallography) in which the open state is like that of bacterial porins with several important differences. Because VDAC does not occur as close-packed trimers, there are probably fewer interpore contacts than in the bacterial porins. VDAC also appears to lack a large, fixed intraluminal segment and may not have as extensive a region of uniformly 35°-tilted β-strands as do the bacterial porins. These structural differences would be expected to render VDAC's β-barrel less stable than its bacterial counterparts, making major conformational changes like those associated with gating more energetically feasible. A possible gating mechanism is suggested in which movement of the N-terminal α-helix out of the lumen wall triggers larger-scale structural changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022489832594
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Localization at Complex I and Mechanism of the Higher Free Radical Production of Brain Nonsynaptic Mitochondria in the Short-Lived Rat Than in the Longevous Pigeon (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 235-243 
    Details
    ISSN: 1573-6881
    Keywords: Aging ; hydrogen peroxide ; mitochondria ; longevity ; bird
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Free radical production and leak of brain nonsynaptic mitochondria were higher with pyruvate/malate than with succinate in rats and pigeons. Rotenone, antimycin A, and myxothiazol maximally stimulated free radical production with pyruvate/malate but not with succinate. Simultaneous treatment with myxothiazol plus antimycin A did not decrease the stimulated rate of free radical production brought about independently by any of these two inhibitors with pyruvate/malate. Thenoyltrifluoroacetone did not increase free radical production with succinate. No free radical production was detected at Complex IV. Free radical production and leak with pyruvate/malate were higher in the rat (maximum longevity 4 years) than in the pigeon (maximum longevity 35 years). These differences between species disappeared in the presence of rotenone. The results localize the main free radical production site of nonsynaptic brain mitochondria at Complex I. They also suggest that the low free radical production of pigeon brain mitochondria is due to a low degree of reduction of Complex I in the steady state in this highly longevous species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020592719405
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Kinetics of the Reconstituted Tricarboxylate Carrier from Eel Liver Mitochondria (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 555-563 
    Details
    ISSN: 1573-6881
    Keywords: Tricarboxylate carrier ; mitochondria ; transport ; liposomes ; kinetics ; reconstitution ; eel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The tricarboxylate carrier from eel liver mitochondria was purified by chromatography on hydroxyapatite and Matrix Gel Blue B and reconstituted into liposomes by removal of the detergent with Amberlite. Optimal transport activity was obtained by using a phospholipid concentration of 11.5 mg/ml, a Triton X-114/phospholipid ratio of 0.9, and ten passages through the same Amberlite column. The activity of the carrier was influenced by the phospholipid composition of the liposomes, being increased by cardiolipin and phosphatidylethanolamine and decreased by phosphatidylinositol. The reconstituted tricarboxylate carrier catalyzed a first-order reaction of citrate/citrate or citrate/malate exchange. The maximum transport rate of external [14C]citrate was 9.0 mmol/min per g of tricarboxylate carrier protein at 25°C and this value was virtually independent of the type of substrate present in the external or internal space of the liposomes. The half-saturation constant (K m) was 62 μM for citrate and 541 μM for malate. The activation energy of the citrate/citrate exchange reaction was 74 kJ/mol from 5 to 19°C and 31 kJ/mol from 19 to 35°C. The rate of the exchange had an external pH optimum of 8.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020532500749
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Reconstitution of the Mitochondrial ATP-Dependent Potassium Channel into Bilayer Lipid Membrane1 (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 159-163 
    Details
    ISSN: 1573-6881
    Keywords: KATP-channel ; solubilization ; mitochondria ; bilayer lipid membrane ; reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Electrical properties and regulation of the mitochondrialATP-dependent potassium channel were studied. The channel protein wassolubilized from the mitochondrial membrane using an ethanol/water mixture.Reconstituted into a bilayer lipid membrane BLM), the protein formed aslightly voltage-dependent channel with a conductance of 10 pS in 100 mM KCl.Often, several channels worked simultaneously (clusters) when many channelswere incorporated into the BLM. The elementary channel and the clusters wereboth highly potassium selective. At concentrations of 1 to 10 μM, ATPfavors channel opening, while channels become closed at 1–3 mM ATP. GDP(0.5 mM) reactivated the ATP-closed channels without affecting the untreatedchannels. The sulfhydryl-reducing agent ditiothreitol increased the openprobability at concentrations of 1 to 3 mM, but damaged the selectivity ofthe channel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005408029549
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    A History of the First Uncoupling Protein, UCP1 (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 399-406 
    Details
    ISSN: 1573-6881
    Keywords: Brown adipose tissue ; mitochondria ; uncoupling protein ; UCP1 ; transport ; nucleotide ; fatty acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The lack of energy conservation in brown adipose tissue mitochondria when prepared byconventional methods was established in the 1960s and was correlated with the thermogenicfunction of the tissue. In order to observe energy conservation, two requirements had to bemet: the removal of the endogenous fatty acids and the addition of a purine nucleotide. Thesetwo factors have been the essential tools that led to the discovery of the energy dissipationpathway, the uncoupling protein UCP1. The activity is regulated by these two ligands. Purinenucleotides bind from the cytosolic side of the protein and inhibit transport. Fatty acids actas seconds messengers of noradrenaline and increase the proton conductance. This reviewpresents a historical perspective of the steps that led to the discovery of UCP1, its regulation,and our current view on its mechanism of transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005436121005
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    The Mechanisms of Fatty Acid-Induced Proton Permeability of the Inner Mitochondrial Membrane (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 447-455 
    Details
    ISSN: 1573-6881
    Keywords: Fatty acid ; uncoupling ; proton permeability ; adenine nucleotide translocase ; dicarboxylate carrier, glutamate/aspartate carrier ; permeability transition pore ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Nonesterified long-chain fatty acids have long been known as uncouplers of oxidativephosphorylation. They are efficient protonophores in the inner mitochondrial membrane but not so inartificial phospholipid membranes. In the un-ionized form, they undergo a rapid spontaneoustransbilayer movement (flip-flop). However, the transbilayer passage of the dissociated(anionic) form is hindered by the negatively charged hydrophilic carboxylic group. In theinner mitochondrial membrane, the transfer of fatty acid anions is mediated by the adeninenucleotide translocase, the dicarboxylate carrier, and the glutamate/aspartate carrier. As a result,the passage of protons and electric charges is a concerted effect of the spontaneous flip-flopof the undissociated (protonated) form in one direction and carrier-facilitated transfer of theionized (deprotonated) form in the other direction. In addition, fatty acids also promote openingof the mitochondrial permeability transition pore, presumably due to their interaction with oneof its constituents, the adenine nucleotide translocase, thus forming an additional route fordissipation of the proton gradient. Structural prerequisites for these proton-conductingmechanisms are (1) a weakly ionized carboxylic group and (2) a hydrocarbon chain of appropriatelength without substituents limiting its mobility and hydrophobicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005444322823
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Proton/electron stoichiometry of mitochondrialbc 1 complex. Influence of pH and transmembrane δpH (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 101-108 
    Details
    ISSN: 1573-6881
    Keywords: bc 1 complex ; mitochondria ; transmembrane pH difference ; cytochromes ; H +/e − stoichiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The effect of pH and transmembrane δpH on the efficiency of the proton pump of the mitochondrialbc 1 complex bothin situ and in the reconstituted state was studied. In both cases the H+/e − ratio for vectorial proton translocation by thebc 1 complex respiring at the steady state, under conditions in which the transmembrane pH difference (δpH) represents the only component of the proton motive force (δp), was significantly lower than that measured under level flow conditions. The latter amounts, at neutral pH, to 1 (2 including the scalar H+ release). In the reconstituted system steady-state δpH was modulated by changing the intravesicular buffer as well as the intra/extra-liposomal pH. Under these conditions the H+/e− ratio varied inversely with the δpH. The data presented show that δpH exerts a critical control on the proton pump of thebc 1 complex. Increasing the external pH above neutrality caused a decrease of the level flowH +/e − ratio. This effect is explained in terms of proton/electron linkage inb cytochromes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110337
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Glycine decarboxylase: Protein chemistry and molecular biology of the major protein in leaf mitochondria (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 407-414 
    Details
    ISSN: 1573-6881
    Keywords: Glycine decarboxylase ; mitochondria ; photorespiration ; gene expression ; light control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The four component proteins of the glycine decarboxylase multienzyme complex (the P-, H-, T-, and L-proteins) comprise over one-third of the soluble proteins in mitochondria isolated from the leaves of C3 plants. Together with serine hydroxymethyltransferase, glycine decarboxylase converts glycine to serine and is the site of photorespiratory CO2 and NH3 release. The component proteins of the complex are encoded on nuclear genes with N-terminal presequences that target them to the mitochondria. The isolated complex readily dissociates into its component proteins and reassociates into the intact complexin vitro. Because of the intimate association between photosynthesis and photorespiration, the proteins of the complex are present at higher levels in leaves in the light. The expression of these genes is controlled at the transcriptional level and the kinetics of expression are closely related to those of the small subunit of Rubisco. Deletion analysis of fusions between the promoter of the H-protein of the complex and the reporter gene β-glucuronidase in transgenic tobacco has identified a region responsible for the tissue specificity and light dependence of gene expression. Gel shift experiments show that a nuclear protein in leaves binds to this region. Glycine decarboxylase has proven to be an excellent system for studying problems in plant biochemistry ranging from protein-protein interactions to control of gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110003
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    URF13, a ligand-gated, pore-forming receptor for T-toxin in the inner membrane ofcms-T mitochondria (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 437-445 
    Details
    ISSN: 1573-6881
    Keywords: Maize ; mitochondria ; cytoplasmic male sterility ; URF13 ; T-urf13 ; T-toxin ; pathogenesis ; pore-forming receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract URF13 is the product of a mitochondrial-encoded gene (T-urfl3) found only in maize plants containing the Texas male-sterile cytoplasm (cms-T), and it is thought to be responsible for both cytoplasmic male sterility and the susceptibility ofcms-T maize to the fungal pathogensBipolaris maydis race T andPhyllosticta maydis. Mitochondria isolated fromcms-T maize are uniquely sensitive to pathotoxins (T-toxin) produced by these fungi and to methomyl (a commercial insecticide). URF13 acts as a receptor that specifically binds T-toxin to produce hydrophilic pores in the inner mitochondrial membrane. When expressed inEscherichia coli cells, URF13 also forms hydrophilic pores in the plasma membrane if exposed to T-toxin or methomyl. Topological studies established that URF13 contains three membrane-spanning α-helices, two of which are amphipathic and can contribute to pore formation. Chemical crosslinking of URF13 was used to demonstrate the existence of URF13 oligomers incms-T mitochondria andE. coli cells. The ability of the carboxylate-specific reagent,N,N∼-dicyclohexycarbodiimide, to cross-link URF13 was used in conjunction with site-directed mutagenesis to establish that the URF13 tetramer has a central core consisting of a four-α-helical bundle which undergoes a conformational change after interaction with T-toxin or methomyl. Overall, the experimental evidence indicates that URF13 functions as a ligand-gated, pore-forming T-toxin receptor incms-T mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110006
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Structure-function relationships of the alternative oxidase of plant mitochondria: A model of the active site (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 367-377 
    Details
    ISSN: 1573-6881
    Keywords: Alternative oxidase ; sequence homology ; hydroxo-bridged di-iron center proteins ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract A major characteristic of plant mitochondria is the presence of a cyanide-insensitive alternative oxidase which catalyzes the reduction of oxygen to water. Current information on the properties of the oxidase is reviewed. Conserved amino acid motifs have been identified which suggest the presence of a hydroxo-bridged di-iron center in the active site of the alternative oxidase. On the basis of sequence comparison with other di-iron center proteins, a structural model for the active site of the alternative oxidase has been developed that has strong similarity to that of methane monoxygenase. Evidence is presented to suggest that the alternative oxidase of plant mitochondria is the newest member of the class II group of di-iron center proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02109999
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Functional molecular aspects of the NADH dehydrogenases of plant mitochondria (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 397-406 
    Details
    ISSN: 1573-6881
    Keywords: Plant ; respiration ; NADH dehydrogenases ; rotenone ; Complex I ; protein purification ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract There are multiple routes of NAD(P)H oxidation associated with the inner membrane of plant mitochondria. These are the phosphorylating NADH dehydrogenase, otherwise known as Complex I, and at least four other nonphosphorylating NAD(P)H dehydrogenases. Complex I has been isolated from beetroot, broad bean, and potato mitochondria. It has at least 32 polypeptides associated with it, contains FMN as its prosthetic group, and the purified enzyme is sensitive to inhibition by rotenone. In terms of subunit complexity it appears similar to the mammalian and fungal enzymes. Some polypeptides display antigenic similarity to subunits fromNeurospora crassa but little cross-reactivity to antisera raised against some beef heart complex I subunits. Plant complex I contains eight mitochondrial encoded subunits with the remainder being nuclear-encoded. Two of these mitochondrial-encoded subunits, nad7 and nad9, show homology to corresponding nuclear-encoded subunits inNeurospora crassa (49 and 30 kDa, respectively) and beef heart CI (49 and 31 kDa, respectively), suggesting a marked difference between the assembly of CI from plants and the fungal and mammalian enzymes. As well as complex I, plant mitochondria contain several type-II NAD(P)H dehydrogenases which mediate rotenone-insensitive oxidation of cytosolic and matrix NADH. We have isolated three of these dehydrogenases from beetroot mitochondria which are similar to enzymes isolated from potato mitochondria. Two of these enzymes are single polypeptides (32 and 55 kDa) and appear similar to those found in maize mitochondria, which have been localized to the outside of the inner membrane. The third enzyme appears to be a dimer comprised of two identical 43-kDa subunits. It is this enzyme that we believe contributes to rotenone-insensitive oxidation of matrix NADH. In addition to this type-II dehydrogenases, several observations suggest the presence of a smaller form of CI present in plant mitochondria which is insensitive to rotenone inhibition. We propose that this represents the peripheral arm of CI in plant mitochondria and may participate in nonphosphorylating matrix NADH oxidation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110002
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Hypothyroidism Leads to a Decreased Expression of Mitochondrial F0F1-ATP Synthase in Rat Liver (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 269-276 
    Details
    ISSN: 1573-6881
    Keywords: Hypothyroidism ; oxidative phophorylation ; mitochondria ; F0F1-ATP synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract In liver mitochondria isolated from hypothyroid rats, the rate of ATP synthesis is lower than in mitochondria from normal rats. Oligomycin-sensitive ATP hydrolase activity and passive proton permeability were significantly lower in submitochondrial particles from hypothyroid rats compared to those isolated from normal rats. In mitochondria from hypothyroid rats, the changes in catalytic activities of F0F1-ATP synthase are accompanied by a decrease in the amount of immunodetected β-F1, F01-PVP, and OSCP subunits of the complex. Northern blot hybridization shows a decrease in the relative cytosolic content of mRNA for β-F1 subunit in liver of hypothyroid rats. Administration of 3,5,3′-triodo-L-thyronine to the hypothyroid rats tends to remedy the functional and structural defects of F0F1-ATP synthase observed in the hypothyroid rats. The results obtained indicate that hypothyroidism leads to a decreased expression of F0F1-ATP synthase complex in liver mitochondria and this contributes to the decrease of the efficiency of oxidative phosphorylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020548904384
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Mitochondrial Redox Signaling during Apoptosis (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 327-334 
    Details
    ISSN: 1573-6881
    Keywords: Apoptosis ; redox ; mitochondria ; E h ; ROS ; ASK-1 ; thioredoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The regulatory role of cellular redox state during apoptosis is still controversial. Early redoxsignaling can transduce divergent upstream signals to mitochondria and initiate apoptosis. Onthe other hand, release of mitochondrial cytochrome c triggers generation of reactive oxygenspecies (ROS) and renders apoptotic cells much more oxidized. Although the sequential caspaseactivation does not have apparent redox-sensitive components, redox signaling provides aseparate pathway that is parallel with the caspase cascade. The function of theapoptosis-associated redox change is uncertain. It could provide positive feedback mechanisms, such asactivating mitochondrial permeability transition and apoptosis signaling kinase (ASK-1). Sinceapoptotic cells are designated to be quickly eliminated, the dramatic cellular oxidation couldbe involved in the final degradation of apoptotic bodies and even the termination of theproteolytic activity after phagocytosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005423818280
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Mitochondrial Oxygen Radical Generation and Leak: Sites of Production in States 4 and 3, Organ Specificity, and Relation to Aging and Longevity (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 347-366 
    Details
    ISSN: 1573-6881
    Keywords: Free radicals ; H2O2 ; complex I ; heart ; brain ; free-radical leak ; complex III ; mitochondria ; aging ; longevity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Studies in heart and nonsynaptic brain mitochondria from two mammals and three birds showthat complex I generates oxygen radicals in heart and nonsynaptic brain mitochondria in States4 and 3, whereas complex III does it only in heart mitochondria and only in State 4. Theincrease in oxygen consumption during the State 4 to 3 transition is not accompanied by aproportional increase in oxygen radical generation. This will protect mitochondria and tissuesduring bursts of activity. Comparisons between young and old rodents do not show a consistentpattern of variation in mitochondrial oxygen radical production during aging. However, allthe interspecies comparisons performed to date between different mammals, and betweenmammals and birds, agree that animals with high maximum longevities have low rates ofmitochondrial oxygen radical production, irrespective of the value of their basal specificmetabolic rate. The sites and mechanisms allowing this, the recently described low degree ofmembrane fatty acid unsaturation of longevous animals, and their relation to longevity andaging are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005427919188
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Anion Carriers in Fatty Acid-Mediated Physiological Uncoupling (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 431-445 
    Details
    ISSN: 1573-6881
    Keywords: Uncoupling ; thermoregulation ; mitochondria ; ATP/ADP antiporter ; aspartate/glutamate antiporter ; uncoupling proteins 1, 2, 3 ; plant uncoupling protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Physiological aspects of uncoupling of oxidation and phosphorylation are reviewed in thecontext of involvement of mitochondrial anion carriers. It is assumed that the carriers facilitateelectrophoretic translation of fatty acid anion, RCOO-, from the inner to the outer leaflet ofthe mitochondrial membrane, whereas back movement of the protonated fatty acid, RCOOH,from the outer to the inner leaflet represents flip-flop of RCOOH via the phospholipid bilayerof the membrane. The RCOO- transport seems to be catalyzed by the ATP/ADP and aspartate/glutamate antiporters, dicarboxylate carrier, and uncoupling proteins (UCP1, UCP2, UCP3L,UCP3s, and plant UCP). The fatty acid uncoupling is shown to be involved in thethermoregulatory heat production in animals and plants exposed to cold, as well as in performance ofrespiratory functions other than ATP synthesis, i.e., formation of useful substances,decomposition of unwanted substances, and antioxidant defense. Moreover, partial uncoupling might takepart in optimization of the rate of ATP synthesis in aerobic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005492205984
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Mitochondrial Proton Leak and the Uncoupling Proteins (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 517-524 
    Details
    ISSN: 1573-6881
    Keywords: Proton leak ; uncoupling proteins ; UCP1 ; UCP2 ; UCP3 ; BMCP1 ; thermogenesis ; sequence homology ; mitochondria ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract An energetically significant leak of protons occurs across the mitochondrial inner membranesof eukaryotic cells. This seemingly wasteful proton leak accounts for at least 20% of thestandard metabolic rate of a rat. There is evidence that it makes a similar contribution tostandard metabolic rate in a lizard. Proton conductance of the mitochondrial inner membranecan be considered as having two components: a basal component present in all mitochondria,and an augmentative component, which may occur in tissues of mammals and perhaps ofsome other animals. The uncoupling protein of brown adipose tissue, UCP1, is a clear exampleof such an augmentative component. The newly discovered UCP1 homologs, UCP2, UCP3,and brain mitochondrial carrier protein 1 (BMCP1) may participate in the augmentativecomponent of proton leak. However, they do not appear to catalyze the basal leak, as this isobserved in mitochondria from cells which apparently lack these proteins. Whereas UCP1plays an important role in thermogenesis, the evidence that UCP2 and UCP3 do likewiseremains equivocal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005456725549
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Inactivation of the Reconstituted Oxoglutarate Carrier from Bovine Heart Mitochondria by Pyridoxal 5′-Phosphate (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 535-541 
    Details
    ISSN: 1573-6881
    Keywords: Oxoglutarate carrier ; pyridoxal 5′-phosphate ; transport ; proteoliposomes ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The effect of pyridoxal 5′-phosphate and some other lysine reagents on the purified,reconstituted mitochondrial oxoglutarate transport protein has been investigated. The inhibition ofoxoglutarate/oxoglutarate exchange by pyridoxal 5′-phosphate can be reversed by passing theproteoliposomes through a Sephadex column but the reduction of the Schiff's base by sodiumborohydride yielded an irreversible inactivation of the oxoglutarate carrier protein. Pyridoxal5′-phosphate, which caused a time- and concentration-dependent inactivation of oxoglutaratetransport with an IC50 of 0.5 mM, competed with the substrate for binding to the oxoglutaratecarrier (K i = 0.4 mM). Kinetic analysis of oxoglutarate transport inhibition by pyridoxal5′-phosphate indicated that modification of a single amino acid residue/carrier molecule wassufficient for complete inhibition of oxoglutarate transport. After reduction with sodiumborohydride [3H]pyridoxal 5′-phosphate bound covalently to the oxoglutarate carrier. Incubation ofthe proteoliposomes with oxoglutarate or L-malate protected the carrier against inactivationand no radioactivity was found associated with the carrier protein. In contrast, glutarate andsubstrates of other mitochondrial carrier proteins were unable to protect the carrier. Mersalyl,which is a known sulfhydryl reagent, also failed to protect the oxoglutarate carrier againstinhibition by pyridoxal 5′-phosphate. These results indicate that pyridoxal 5′-phosphateinteracts with the oxoglutarate carrier at a site(s) (i.e., a lysine residue(s) and/or the amino-terminalglycine residue) which is essential for substrate translocation and may be localized at or nearthe substrate-binding site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026414826457
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    5-Aminolevulinate synthase and the first step of heme biosynthesis (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 151-159 
    Details
    ISSN: 1573-6881
    Keywords: Heme ; 5-aminolevulinate ; pyridoxal 5′-phosphate ; mitochondria ; heme metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract 5-Aminolevulinate synthase catalyzes the condensation of glycine and succinyl-CoA to yield 5-aminolevulinate. In animals, fungi, and some bacteria, 5-aminolevulinate synthase is the first enzyme of the heme biosynthetic pathway. Mutations on the human erythroid 5-aminolevulinate synthase, which is localized on the X-chromosome, have been associated with X-linked sideroblastic anemia. Recent biochemical and molecular biological developments provide important insights into the structure and function of this enzyme. In animals, two aminolevulinate synthase genes, one housekeeping and one erythroid-specific, have been identified. In addition, the isolation of 5-aminolevulinate synthase genomic and cDNA clones have permitted the development of expression systems, which have tremendously increased the yields of purified enzyme, facilitating structural and functional studies. A lysine residue has been identified as the residue involved in the Schiff base linkage of the pyridoxal 5′-phosphate cofactor, and the catalytic domain has been assigned to the C-terminus of the enzyme. A conserved glycine-rich motif, common to all aminolevulinate synthases, has been proposed to be at the pyridoxal 5′phosphate-binding site. A heme-regulatory motif, present in the presequences of 5-aminolevulinate synthase precursors, has been shown to mediate the inhibition of the mitochondrial import of the precursor proteins in the presence of heme. Finally, the regulatory mechanisms, exerted by an iron-responsive element binding protein, during the translation of erythroid 5-aminolevulinate synthase mRNA, are discussed in relation to heme biosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110030
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    The First Steps of Protein Import into Mitochondria (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 11-17 
    Details
    ISSN: 1573-6881
    Keywords: Protein targeting ; protein import ; mitochondria ; molecular chaperones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Protein import into mitochondria is initiated by the recognition and binding of precursor proteins by import components in the cytosol, on the mitochondrial surface, and in the mitochondrial outer membrane. Following their synthesis on cytoplasmic ribosomes, some precursor proteins interact with molecular chaperones in the cytosol which function in maintaining the precursor protein in an import-competent state and may also aid in the delivery of the precursor to the mitochondria. A multisubunit protein import receptor then recognises and binds precursor proteins before feeding them into the outer membrane import site. Some proteins are sorted from the import site into the outer membrane, but most precursor proteins travel through the outer membrane import site into the mitochondria, where the later steps of protein import take place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022451520203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Molecular Chaperones and Mitochondrial Protein Folding (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 35-43 
    Details
    ISSN: 1573-6881
    Keywords: Chaperonins ; heat-shock proteins ; mitochondria ; molecular chaperones ; protein folding ; protein import
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Precursor proteins destined for the mitochondrial matrix traverse inner and outer organelle membranes in an extended conformation. Translocation events are therefore integrally coupled to the processes of protein unfolding in the cytosol and protein refolding in the matrix. To successfully import proteins from the cytoplasm into mitochondria, cells have recruited a variety of molecular chaperone systems and folding catalysts. Within the organelles, mitochondrial Hsp70 (mt-Hsp70) is a major player in this process and exerts multiple functions. First, mt-Hsp70 binds together with cohort proteins to incoming polypeptide chains, thus conferring unidirectionality on the translocation process, and then assists in their refolding. A subset of imported proteins requires additional assistance by chaperonins of the Hsp60/Hsp10 family. Protein folding occurs within the cavity of these cylindrical complexes. A productive interaction of precursor proteins with molecular chaperones in the matrix is not only crucial for correct refolding and assembly, but also for processing of presequences, intramitochondrial sorting, and degradation of proteins. This review focuses on the role of mt-Hsp70 and Hsp60/Hsp10 in protein folding in the mitochondrial matrix and discusses recent findings on their molecular mechanism of action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022407705182
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Proton Pumping of Mitochondrial Complex I: Differential Activation by Analogs of Ubiquinone (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 71-80 
    Details
    ISSN: 1573-6881
    Keywords: NADH: ubiquinone reductase ; ubiquinone ; proton pumping ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract As part of the ongoing studies aimed at elucidating the mechanism of the energy conserving function of mitochondrial complex I, NADH: ubiquinone (Q) reductase, we have investigated how short-chain Q analogs activate the proton pumping function of this complex. Using a pH-sensitive fluorescent dye we have monitored both the extent and initial velocity of proton pumping of complex I in submitochondrial particles. The results are consistent with two sites of interaction of Q analogs with complex I, each having different proton pumping capacity. One is the physiological site which leads to a rapid proton pumping and a stoichiometric consumption of NADH associated with the reduction of the most hydrophobic Q analogs. Of these, heptyl-Q appears to be the most efficient substrate in the assay of proton pumping. Q analogs with a short-chain of less than six carbons interact with a second site which drives a slow proton pumping activity associated with NADH oxidation that is overstoichiometric to the reduced quinone acceptor. This activity is also nonphysiological, since hydrophilic Q analogs show little or no respiratory control ratio of their NADH:Q reductase activity, contrary to hydrophobic Q analogs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022415906999
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Homologous and Heterologous Interactions between Hexokinase and Mitochondrial Porin: Evolutionary Implications (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 97-102 
    Details
    ISSN: 1573-6881
    Keywords: Hexokinase ; binding to mitochondria ; mitochondria ; binding of hexokinase to ; Porin ; VDAC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Binding of the Type I isozyme of mammalian hexokinase to mitochondria is mediated by the porin present in the outer mitochondrial membrane. Type I hexokinase from rat brain is avidly bound by rat liver mitochondria while, under the same conditions, there is no significant binding to mitochondria from S. cerevisiae. Previously published work demonstrates the lack of significant interaction of yeast hexokinase with mitochondria from either liver or yeast. Thus, structural features required for the interaction of porin and hexokinase must have emerged during evolution of the mammalian forms of these proteins. If these structural features serve no functional role other than facilitating this interaction of hexokinase with mitochondria, it seems likely that they evolved in synchrony since operation of selective pressures on the hexokinase–mitochondrial interaction would require the simultaneous presence of hexokinase and porin capable of at least minimal interaction, and be responsive to changes in either partner that affected this interaction. Recent studies have indicated that a second type of binding site, which may or may not involve porin, is present on mammalian mitochondria. There are also reports of hexokinase binding to mitochondria in plant tissues, but the nature of the binding site remains undefined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022472124746
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    ADP-Regulation of Mitochondrial Free Radical Production Is Different with Complex I- or Complex II-Linked Substrates: Implications for the Exercise Paradox and Brain Hypermetabolism (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 241-249 
    Details
    ISSN: 1573-6881
    Keywords: ADP ; mitochondria ; free radical production ; brain ; heart ; exercise ; hypermetabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract In agreement with classic studies, succinate-supplemented rat and pigeon heart and nonsynaptic brain mitochondrial free radical production is stopped by ADP additions causing the stimulation of respiration from State 4 to State 3. Nevertheless, with Complex I-linked substrates, mitochondria produce free radicals in State 3 at rates similar or somewhat higher than during resting respiration. The absence of sharp increases in free radical production during intense respiration is possible due to strong decreases of free radical leak in State 3. The results indicate that Complex I is the main mitochondrial free radical generator in State 3, adding to its already known important generation of active oxygen species in State 4. The observed rate of mitochondrial free radical production with Complex I-linked substrates in the active State 3 can help to explain two paradoxes: (a) the lack of massive muscle oxidative damage and shortening of life span due to exercise, in spite of up to 23-fold increases of oxygen consumption together with the very low levels of antioxidants present in heart, skeletal muscle, and brain; (b) the presence of some degree of oxidative stress during exercise and hyperactivity in spite of the stop of mitochondrial free radical production by ADP with succinate as substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022458010266
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Localized Firefly Luciferase Probes ATP at the Surface of Mitochondria (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 549-559 
    Details
    ISSN: 1573-6881
    Keywords: Luciferase ; localized probe ; heterogeneous coupled systems ; mitochondria ; hexokinase ; nucleotide concentration gradients ; cellular catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The concentration of ATP generated by yeast mitochondria and consumed by yeast hexokinase was monitored using native firefly luciferase in solution, or recombinant luciferase localized at the surface of mitochondria. In the absence of hexokinase, both probes perform similarly in detecting exogenous or mitochondrially-generated ATP. The steady-state concentrations of ATP can be reduced in a dose-dependent manner by hexokinase. With hexokinase added in large excess, the localized probe reports substantial ATP concentrations while none is detectable by soluble luciferase. Thus, ATP accumulates near the membrane where it appears, relatively to solution, and vice versa for ADP. The extent of nucleotide gradients is shown to be correlated with the specific activity of oxidative phosphorylation and with the viscosity of the medium, but independent of the concentration of the organelles. A simple model involving diffusional restrictions is presented to describe this behavior. The metabolic and evolutionary implications of cellular catalysis limitation by physical processes are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022478917573
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Mitochondrial Ca2+ Transients in Cardiac Myocytes During the Excitation–Contraction Cycle: Effects of Pacing and Hormonal Stimulation (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 207-222 
    Details
    ISSN: 1573-6881
    Keywords: Calcium ; cardiac myocytes ; confocal microscopy ; Fluo 3 ; Indo 1 ; isoproterenol ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Using laser scanning confocal microscopy, our objective was to measure mitochondrial, nuclear, and cytosolic free ionized Ca2+ in adult rabbit cardiac myocytes loaded with Ca2+-indicating fluorophores. When myocytes were loaded with Fluo 3 at 37°C, the fluorophore was loaded extensively into the cytosol and nucleus, but poorly into mitochondria, and Fluo 3 fluorescence transients after field stimulation were confined to the cytosol and nucleus. In contrast, after loading at 4°C, Fluo 3 also entered mitochondria, and large transients of mitochondrial Fluo 3 fluorescence then occurred after stimulation. Isoproterenol (1 μM) increased the magnitude of Ca2+ transients and their subsequent rate of decay, an effect more marked in the cytosol and nucleus than in mitochondria. As pacing frequency was increased from 0.5 to 2 Hz, diastolic mitochondrial Ca2+ rose markedly in the absence but not in the presence of isoproterenol. Resting Ca2+ estimated by Indo 1 ratio imaging using UV/visible laser scanning confocal microscopy was about 200 nM in all compartments. During field stimulation, Ca2+ transiently increased to 671, 522, and 487 nM in cytosol, interfibrillar mitochondria, and perinuclear mitochondria, respectively. Isoproterenol increased these respective peak values to 1280, 750, and 573 nM. These results were consistent with those obtained in Fluo 3 experiments. We conclude that rapid mitochondrial Ca2+ transients occur during excitation–contraction coupling in adult rabbit cardiac myocytes, which may be important in matching mitochondrial metabolism to myocardial ATP demand during changes in cardiac output.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020588618496
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Electron Tomography of Mitochondria from Brown Adipocytes Reveals Crista Junctions (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 431-442 
    Details
    ISSN: 1573-6881
    Keywords: BAT mitochondria ; brown adipocytes ; contact sites ; crista junctions ; cristae ; cristae structure ; electron microscopy ; electron microscope tomography ; mitochondria ; mitochondrial structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Electron microscope tomography was used to examine the membrane topology of brown adipose tissue (BAT) mitochondria prepared by cryofixation or chemical fixation techniques. These mitochondria contain an uncoupling protein which results in the conversion of energy from electron transport into heat. The three-dimensional reconstructions of BAT mitochondria provided a view of the inner mitochondrial membrane different in important features from descriptions found in the literature. The work reported here provides new insight into BAT mitochondria architecture by identifying crista junctions, including multiple junctions connecting a crista to the same side of the inner boundary membrane, in a class of mitochondria that have no tubular cristae, but only lamellar cristae. Crista junctions were defined previously as the tubular membranes of relatively uniform diameter that connect a crista membrane with the inner boundary membrane. We have also found that the cristae architecture of cryofixed mitochondria, including crista junctions, is similar to that found in chemically fixed mitochondria, suggesting that this architecture is not a fixation artifact. The stacks of lamellar cristae extended through more of the BAT mitochondrial volume than did the cristae we observed in neuronal mitochondria. Hence, the inner membrane surface area was larger in the former. In chemically fixed mitochondria, contact sites were easily visualized because the outer and inner boundary membranes were separated by an 8 nm space. However, in cryofixed mitochondria almost all the outer membrane was observed to be in close contact with the inner boundary membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020586012561
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Subunit f of the Yeast Mitochondrial ATP Synthase: Topological and Functional Studies (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 85-94 
    Details
    ISSN: 1573-6881
    Keywords: yeast ; mitochondria ; ATP synthase ; ATP17 gene ; subunit f ; orientation ; cross-linking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Modified versions of subunit f were produced by mutagenesis of theATP17 gene of Saccharomyces cerevisiae. A version of subunit f devoid of thelast 28 amino acid residues including the unique transmembranous domaincomplemented the oxidative phosphorylation of the null mutant. However, atwo-fold decrease in the specific ATP synthase activity was measured andattributed to a decrease in the stability of the mutant ATP synthase complexas shown by the low oligomycin-sensitive ATPase activity at alkaline pH. Themodification or not by non-permeant maleimide reagents of cysteine residuesintroduced at the N and C termini of subunit f indicated aNin-Cout orientation. From the C terminus of subunit fit was possible to cross-link subunit 4 (also called subunit b), which isanother component of the F0 sector and which also displays a shorthydrophilic segment exposed to the intermembrane space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005407525915
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    The Role of the Amino-Terminal β-Barrel Domain of the α and β Subunits in the Yeast F1-ATPase (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 95-104 
    Details
    ISSN: 1573-6881
    Keywords: F1-ATPase ; β-barrel domain ; mitochondria ; assembly ; yeast ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The crystal structure of mitochondrial F1-ATPase indicatesthat the α and β subunits fold into a structure defined by threedomains: the top β-barrel domain, the middle nucleotide-binding domain,and the C-terminal α-helix bundle domain (Abraham et al.1994); Bianchet et al., 1998). The β-barrel domains of theα and β subunits form a crown structure at the top ofF1, which was suggested to stabilize it (Abraham et al.1994). In this study. the role of the β-barrel domain in the α andβ subunits of the yeast Saccharomyces cerevisiae F1,with regard to its folding and assembly, was investigated. The β-barreldomains of yeast F1 α and β subunits were expressedindividually and together in Escherichia coli. When expressedseperately, the β-barrel domain of the β subunit formed a largeaggregate structure, while the domain of the α subunit waspredominately a monomer or dimer. However, coexpression of the β-barreldomain of α subunit domain. Furthermore, the two domains copurified incomplexes with the major portion of the complex found in a small molecularweight form. These results indicate that the β-barrel domain of theα and β subunits interact specifically with each other and thatthese interactions prevent the aggregation of the β-barrel domain of theβ subunit. These results mimic in vivo results and suggest thatthe interactions of the β-barrel domains may be critical during thefolding and assembly of F1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005443609985
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    On the Role of the General Transcription Factor Sp1 in the Activation and Repression of Diverse Mammalian Oxidative Phosphorylation Genes* (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 129-135 
    Details
    ISSN: 1573-6881
    Keywords: mitochondria ; promoter ; transcription regulation ; Sp1 ; repressor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract To gain insight into the role of the general transcription factor,Sp1, in the expression of nuclear genes involved in mitochondrial biogenesis,we investigated Sp1 activation of the adenine nucleotide translocator 2,cytochrome c1, F1-ATPase β subunit, and themitochondria transcription factor (mtTFA) promoters transfected intoDrosophila cell lines. The numbers and organization of GC elementsvary in the four promoters, but the magnitude of activation by coexpressedhuman Sp1 was similar. A feature common to the four promoters is the presenceof multiple, proximal Sp1-activating elements that account for 50% ormore of the transcription activation by Sp1. The distribution and function ofindividual distal Sp1 elements is less defined and appear to be morepromoter-specific. Finally, data from transfected Drosophila cellsprovide the first direct proof for the involvement of Sp1 in the negativeregulation of the ANT2 promoter and as a possible participant in repressionof the β-subunit promoter. The role of Sp1 in both the positive andnegative regulation of OXPHOS promoters is unique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005499727732
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Activation and Deactivation of F0F1-ATPase in Yeast Mitochrondia (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 105-117 
    Details
    ISSN: 1573-6881
    Keywords: mitochondria ; F0F1 ATPase ; ATP synthase ; ATP hydrolysis ; IF1 ; yeast ; regulation ; inactivation ; proton gradient ; detergent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The regulation of membrane-bound proton F0F1ATPase by the protonmotive force and nucleotides was studied in yeastmitochondria. Activation occurred in whole mitochondria and the ATPaseactivity was measured just after disrupting the membranes with Triton X-100.Deactivation occurred either in whole mitochondria uncoupled with FCCP, or indisrupted membranes. No effect of Triton X-100 on the ATPase was observed,except a slow reactivation observed only in the absence of MgADP. BothAMPPNP and ATP increased the ATPase deactivation rate, thus indicating thatoccupancy of nucleotidic sites by ATP is more decisive than catalyticturnover for this process. ADP was found to stimulate the energy-dependentATPase activation. ATPase deactivated at the same rate in uncoupled anddisrupted mitochondria. This suggests that deactivation is not controlled byrebinding of some soluble factor, like IF1, but rather by the conversion ofthe F1.IF1 complex into an inactive form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005495626823
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Mutation of K234 and K236 in the Voltage-Dependent Anion Channel 1 Impairs Its Insertion into the Mitochondrial Outer Membrane (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 137-142 
    Details
    ISSN: 1573-6881
    Keywords: VDAC1 ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Previous in vitro studies indicated that mutation of bothK234 and K236 to arginine, glutamine, or glutamic acid impaired the abilityof the voltage-dependent anion channel (VDAC1) to insert into the outermembrane of the mitochondria (Smith et al. 1995). These same mutantswere expressed in a strain of Saccharomyces cerevisiae with adisruption in the VDAC1 gene. The mutant VDAC1 forms were found in themitochondria suggesting that they were correctly sorted to the outermembrane. However, only very small amounts of the mutants were inserted intothe mitochondrial membranes. Mitochondria isolated from the strains expressingthe mutants were capable of catalyzing the translocation of both wild-typeVDAC1 and pre-alcohol dehydrogenase III indicating that the translocationapparatus was functional. These results confirm the previously drawnconclusion that K234 and K236 are part of a membrane insertion motif. Thefailure of the mutant VDAC1 forms to insert did not cause VDAC1 precursors toaccumulate in the soluble cell cytoplasm or in the microsomal fraction. Theapparent lack of a “precursor pool” suggested that apost-transcriptional control mechanism might limit the amounts of VDAC1precursors in the cell. Such a control mechanism is consistent with theobservation that the amount of VDAC1 was very similar after epichromosomal(gene in a 2u plasmid controlled by a Gal1 promoter) and chromosomalexpression (endogenous gene controlled by the endogenous promoter).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005451811802
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Mutations in the Voltage-Dependent Anion Channel of the Mitochondrial Outer Membrane Cause a Dominant Nonlethal Growth Impairment (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 143-151 
    Details
    ISSN: 1573-6881
    Keywords: VDAC1 ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Point mutations at K234 and K236 in the yeast voltage-dependent anionchannel 1 (VDAC1) of the mitochondrial outer membrane have been shown tomarkedly impair the membrane insertion of this protein (Smith etal., 1995; Angeles et al., 1998). Mutants of this type wereexpressed in vivo in a strain of yeast with a disruption in theVDAC1 gene. Expression of the various VDAC1 forms was under the control of aGal1 promoter. Wild-type VDAC1 expression fully complemented the slow growthphenotype caused by the disruption. VDAC1 mutants in which K234 and K236 werereplaced by arginine, glutamate, or glutamine caused a more severe negativeeffect on growth. This effect appeared to be dominant since the mutant VDAC1forms suppressed growth in a yeast strain that retained its VDAC1 gene. Thisapparent dominant negative effect on growth did not seem to be specific forany stage of the cell cycle. However, the growth defect was not lethal as theaffected cells still could accumulate the vital stain, FUN1. Expression of amutant in which K234 had been replaced by glutamate had more serious negativegrowth effects than did a similar mutation at K236. Expression ofΔ71-116 VDAC1 complemented the VDAC1 disruption; however, expression ofthe same deletion mutant in which the lysines corresponding to K234 and K236were mutated to glutamate severely impaired growth. These results have shownthat a deficiency of lysine at positions 234 and 236 in VDAC1 causes anonlethal growth defect that is more severe than deletion of 45 amino acidsfrom VDAC1 or disruption of the VDAC1 gene. They also indicate that there is ahierarchy in the importance of these lysines with mutations at K234 being themore serious.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005403928641
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Mitochondrial Events in the Life and Death of Animal Cells: A Brief Overview (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 291-304 
    Details
    ISSN: 1573-6881
    Keywords: Cell death ; aging ; necrosis ; apoptosis ; mitochondria ; oxidative phosphorylation ; electron transport chain ; ATP synthase ; cytochrome c ; mitochondrial DNA ; reactive oxygen species (ROS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Traditionally, mitochondria have been viewed as the “powerhouse” of the cell, i.e., the site of theoxidative phosphorylation machinery involved in ATP production. Consequently, much of theresearch conducted on mitochondria over the past 4 decades has focused on elucidating both thosemolecular events involved in ATP synthesis by oxidative phosphorylation and those involved inthe biogenesis of the oxidative phosphorylation machinery. While monumental achievements havebeen made, and continue to be made, in the study of these remarkable but extremely complexprocesses essential for the life of most animal cells, it has been only in recent years that a largebody of biological and biomedical scientists have come to recognize that mitochondria participatein other important processes. Two of these are cell death and aging which, not surprisingly, are relatedprocesses both involving, in part, the oxidative phosphorylation machinery. This new awareness hassparked a new and growing area of mitochondrial research, that has become of great interest to awide variety of scientists ranging from those involved in elucidating the role of mitochondria incell death and aging to those interested in either suppressing or facilitating these processes as itrelates to identifying new therapies or drugs for human disease. It is the purpose of this briefintroductory review to provide an overview of those mitochondrial events involved in the life anddeath of animal cells and to indicate how these events might relate to the human aging process.Much more is known, much remains controversial, and even more remains to be learned as indicatedin the excellent set of minireviews that follow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005453700533
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Inhibitory Properties of Ruthenium Amine Complexes on Mitochondrial Calcium Uptake (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 551-557 
    Details
    ISSN: 1573-6881
    Keywords: Calcium uniporter inhibitors ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The recent finding that the inhibition of Ca2+-stimulated respiration by ruthenium red is mainlydue to a binuclear ruthenium complex (Ru360) present in the commercial samples of the classicalinhibitor ruthenium red (Ying et. al., 1991), showed that this complex is the more potent andspecific inhibitor of the mitochondrial calcium uniporter. This work was aimed to provideinsights into the mechanism by which Ru360 and other ruthenium-related compounds inhibitscalcium uptake. Ruthenium red and a synthesized analog (Rrphen) were compared with Ru360.The inhibition by this binuclear complex was noncompetitive, with a K i of 9.89 nM. Thenumber of specific binding sites for Ru360 was 6.2 pmol/mg protein. Ruthenium red and Ru360were mutually exclusive inhibitors. Bound La3+ was not displaced by Ru360. Rrphen was theleast effective for inhibiting calcium uptake. The results support the notion of a specific bindingsite in the uniporter for the polycationic complexes and a negative charged region from thephospholipids in the membrane, closely associated with the uniporter inhibitor-binding site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005464927366
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Structure and function of ferrochelatase (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 221-229 
    Details
    ISSN: 1573-6881
    Keywords: Heme ; porphyrin ; mitochondria ; iron-sulfur cluster ; heme metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Ferrochelatase is the terminal enzyme of the heme biosynthetic pathway in all cells. It catalyzes the insertion of ferrous iron into protoporphyrin IX, yielding heme. In eukaryotic cells, ferrochelatase is a mitochondrial inner membrane-associated protein with the active site facing the matrix. Decreased values of ferrochelatase activity in all tissues are a characteristic of patients with protoporphyria. Point-mutations in the ferrochelatase gene have been recently found to be associated with certain cases of erythropoietic protoporphyria. During the past four years, there have been considerable advances in different aspects related to structure and function of ferrochelatase. Genomic and cDNA clones for bacteria, yeast, barley, mouse, and human ferrochelatase have been isolated and sequenced. Functional expression of yeast ferrochelatase in yeast strains deficient in this enzyme, and expression inEscherichia coli and in baculovirusinfected insect cells of different ferrochelatase cDNAs have been accomplished. A recently identified (2Fe-2S) cluster appears to be a structural feature shared among mammalian ferrochelatases. Finally, functional studies of ferrochelatase site-directed mutants, in which key amino acids were replaced with residues identified in some cases of protoporphyria, will be summarized in the context of protein structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110037
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    The irreversibility of inner mitochondrial membrane permeabilization by Ca2+ plus prooxidants is determined by the extent of membrane protein thiol cross-linking (1996)
    Springer
    Journal of bioenergetics and biomembranes 28 (1996), S. 523-529 
    Details
    ISSN: 1573-6881
    Keywords: Calcium ; cyclosporin A ; mitochondria ; mitochondrial permeability transition pore ; protein oxidation ; reactive oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract We have previously shown that mitochondrial membrane potential (δψ) drop promoted by prooxidants and Ca2+ can be reversed but not sustained by ethylene glycol-bis(β-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA) unless dithiothreitol (DTT), a disulfide reductant, is also added [Valle, V. G. R., Fagian, M. M., Parentoni, L. S., Meinicke, A. R., and Vercesi, A. E. (1993).Arch. Biochem. Biophys. 307, 1–7]. In this study we show that catalase or ADP are also able to potentiate this EGTA effect. When EGTA is added long after (12 min) the completion of swelling or δψ elimination, no membrane resealing occurs unless the EGTA addition was preceded by the inclusion of DTT, ADP, or catalase soon after δψ was collapsed. Total δψ recovery by EGTA is obtained only in the presence of ADP. The sensitivity of the ADP effect to carboxyatractyloside strongly supports the involvement of the ADP/ATP carrier in this mechanism. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of solubilized membrane proteins shows that protein aggregation due to thiol cross-linkage formed during δψ drop continues even after δψ is already eliminated. Titration with 5,5′-dithio-bis(2-nitrobenzoic acid) supports the data indicating that the formation of protein aggregates is paralleled by a decrease in the content of membrane protein thiols. Since the presence of ADP and EGTA prevents the progress of protein aggregation, we conclude that this process is responsible for both increased permeability to larger molecules and the irreversibility of δΩ drop. The protective effect of catalase suggests that the continuous production of protein thiol cross-linking is mediated by mitochondrial generated reactive oxygen species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110442
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Lineage-Specific Evolution of Echinoderm Mitochondrial ATP Synthase Subunit 8 (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 233-239 
    Details
    ISSN: 1573-6881
    Keywords: ATP synthase subunit 8 ; genes ; mammals ; mitochondria ; sea urchins ; sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Peculiar evolutionary properties of the subunit 8 of mitochondrial ATP synthase (ATPase8) are revealed by comparative analyses carried out between both closely and distantly related species of echinoderms. The analysis of nucleotide substitution in the three echinoids demonstrated a relaxation of amino acid functional constraints. The deduced protein sequences display a well conserved domain at the N-terminus, while the central part is very variable. At the C-terminus, the broad distribution of positively charged amino acids, which is typical of other organisms, is not conserved in the two different echinoderm classes of the sea urchins and of the sea stars. Instead, a motif of three amino acids, so far not described elsewhere, is conserved in sea urchins and is found to be very similar to the motif present in the sea stars. Our results indicate that the N-terminal region seems to follow the same evolutionary pattern in different organisms, while the maintenance of the C-terminal part in a phylum-specific manner may reflect the co-evolution of mitochondrial and nuclear genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022406026196
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Early Bioenergetic Changes in Hepatocarcinogenesis: Preneoplastic Phenotypes Mimic Responses to Insulin And Thyroid Hormone (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 303-313 
    Details
    ISSN: 1573-6881
    Keywords: Hepatic preneoplasia ; glycogenotic foci ; amphophilic foci ; mitochondria ; peroxisomes ; hepatocellular neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Biochemical and molecular biological approaches in situ have provided compelling evidence for early bioenergetic changes in hepatocarcinogenesis. Hepatocellular neoplasms regularly develop from preneoplastic foci of altered hepatocytes, irrespective of whether they are caused by chemicals, radiation, viruses, or transgenic oncogenes. Two striking early metabolic aberrations were discovered: (1) a focal excessive storage of glycogen (glycogenosis) leading via various intermediate stages to neoplasms, the malignant phenotype of which is poor in glycogen but rich in ribosomes (basophilic), and (2) an accumulation of mitochondria in so-called oncocytes and amphophilic cells, giving rise to well-differentiated neoplasms. The metabolic pattern of human and experimentally induced focal hepatic glycogenosis mimics the phenotype of hepatocytes exposed to insulin. The conversion of the highly differentiated glycogenotic hepatocytes to the poorly differentiated cancer cells is usually associated with a reduction in gluconeogenesis, an activation of the pentose phosphate pathway and glycolysis, and an ever increasing cell proliferation. The metabolic pattern of preneoplastic amphophilic cell populations has only been studied to a limited extent. The few available data suggest that thyromimetic effects of peroxisomal proliferators and hepadnaviral infection may be responsible for the emergence of the amphophilic cell lineage of hepatocarcinogenesis. The actions of both insulin and thyroid hormone are mediated by intracellular signal transduction. It is, thus, conceivable that the early changes in energy metabolism during hepatocarcinogenesis are the consequence of alterations in the complex network of signal transduction pathways, which may be caused by genetic as well as epigenetic primary lesions, and elicit adaptive metabolic changes eventually resulting in the malignant neoplastic phenotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022438528634
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Butylated hydroxytoluene and inorganic phosphate plus Ca2+ increase mitochondrial permeability via mutually exclusive mechanisms (1996)
    Springer
    Journal of bioenergetics and biomembranes 28 (1996), S. 199-206 
    Details
    ISSN: 1573-6881
    Keywords: Butylated hydroxytoluene ; mitochondria ; permeability transition ; phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Mitochondria undergo a permeability transition (PT), i.e., become nonselectively permeable to small solutes, in response to a wide range of conditions/compounds. In general, opening of the permeability transition pore (PTP) is Ca2+- and Pi-dependent and is blocked by cyclosporin A (CsA), trifluoperazine (TFP), ADP, and butylated hydroxytoluene (BHT). Gudz and coworkers have reported [7th European Bioenergetics Conference, EBEC Short Reports (1992)7, 125], however, that, under some conditions, BHT increases mitochondrial permeability via a process that may not share all of these characteristics. Specifically, they determined that the BHT-induced permeability transition was independent of Ca2+ and was insensitive to CsA. We have used mitochondrial swelling to compare in greater detail the changes in permeability induced by BHT and by Ca2+ plus Pi with the following results. (1) The dependence of permeability on BHT concentration is triphasic: there is a threshold BHT concentration (ca. 60 nmol BHT/ mg mitochondrial protein) below which no increase occurs; BHT enhances permeability in an intermediate concentration range; and at high BHT concentrations (〉 120 nmol/mg) permeability is again reduced. (2) The effects of BHT depend on the ratio of BHT to mitochondrial protein. (3) Concentrations of BHT too low to induce swelling block the PT induced by Ca2+ and Pi. (4) The dependence of the Ca2+-triggered PT on Pi concentration is biphasic. Below a threshold of 50–100 ΜM, no swelling occurs. Above this threshold swelling increases rapidly. (5) Pi levels too low to support the Ca2+-induced PT inhibit BHT-induced swelling. (6) Swelling induced by BHT can bestimulated by agents and treatments that block the PT induced by Ca2+ plus Pi. These data suggest that BHT and Ca2+ plus Pi, increase mitochondrial permeability via two mutually exclusive mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110651
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Human Cytochrome c Oxidase: Structure, Function, and Deficiency (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 151-163 
    Details
    ISSN: 1573-6881
    Keywords: cytochrome c oxidase ; respiratory chain ; mitochondria ; assembly ; enzyme deficiency ; Leigh's syndrome ; mitochondrial myopathy (Saccharomyces cerevisiae, human)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract As the terminal component of the mitochondrial respiratory chain, cytochrome c oxidase plays a vital role in cellular energy transformation. Human cytochrome c oxidase is composed of 13 subunits. The three major subunits form the catalytic core and are encoded by mitochondrial DNA (mtDNA). The remaining subunits are nuclear-encoded. The primary sequence is known for all human subunits and the crystal structure of bovine heart cytochrome c oxidase has recently been reported. However, despite this wealth of structural information, the role of the nuclear-encoded subunits is still poorly understood. Yeast cytochrome c oxidase is a close model of its human counterpart and provides a means of studying the effects of mutations on the assembly, structure, stability and function of the enzyme complex. Defects in cytochrome c oxidase function are found in a clinically heterogeneous group of disorders. The molecular defects that underlie these diseases may arise from mutations of either the mitochondrial or the nuclear genomes or both. A significant number of cytochrome c oxidase deficiencies, often associated with other respiratory chain enzyme defects, are attributed to mutations of mtDNA. Mutations of mtDNA appear, nonetheless, uncommon in early childhood. Pedigree analysis and cell fusion experiments have demonstrated a nuclear involvement in some infantile cases but a specific nuclear genomic lesion has not yet been reported. Detailed analyses of the many steps involved in the biogenesis of cytochrome c oxidase, often pioneered in yeast, offer several starting points for further molecular characterizations of cytochrome c oxidase deficiencies observed in clinical practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022638013825
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    The bifunctional cytochromec reductase/processing peptidase complex from plant mitochondria (1995)
    Springer
    Journal of bioenergetics and biomembranes 27 (1995), S. 423-436 
    Details
    ISSN: 1573-6881
    Keywords: Cytochromec reductase ; bc 1 complex ; respiratory chain ; mitochondrial processing peptidase ; protein import ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Cytochromec reductase from potato has been extensively studied with respect to its catalytic activities, its subunit composition, and the biogenesis of individual subunits. Molecular characterization of all 10 subunits revealed that the high-molecular-weight subunits exhibit striking homologies with the components of the general mitochondrial processing peptidase (MPP) from fungi and mammals. Some of the other subunits show differences in the structure of their targeting signals or in their molecular composition when compared to their counterparts from heterotrophic organisms. The proteolytic activity of MPP was found in the cytochromec reductase complexes from potato, spinach, and wheat, suggesting that the integration of the protease into this respiratory complex is a general feature of higher plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110005
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Cooperation of a “Reactive Oxygen Cycle” with The Q Cycle and The Proton Cycle in the Respiratory Chain—Superoxide Generating and Cycling Mechanisms in Mitochondria (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 367-376 
    Details
    ISSN: 1573-6881
    Keywords: Superoxide generation ; protonmotive force dependent ; protonophore ; proton leak ; heat production ; ROS cycle ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Based on our recent findings concerning the generating, partitioning, targeting, and functioningof superoxide in mitochondria, a hypothetical model involving a “reactive oxygen cycle” inthe respiratory chain has been proposed (Liu and Huang, 1991, 1996; Liu et al., 1996; Liu,1997, 1998) This model emphasizes that during State 4 respiration, an interaction between anelectron leak (a branch of electron transfer directly from the respiratory chain to form O•- 2,but not H2O) and a proton leak (a branch pathway which utilizes $$\Delta \mu _{{\text{H}}^{\text{ + }} } $$ to produce heat, butnot ATP) may take place in cooperation with the Q and proton cycles in mitochondria throughthe consumption of H+ by O•- 2 anions to form a protonated perhydroxyl radical, HO2, whichis directly permeable across the inner mitochondrial membrane and induces proton leakageand a decrease of $$\Delta \mu _{{\text{H}}^{\text{ + }} } $$ . O•- 2 generation in the mitochondrial respiratory chain and its cyclingacross the inner membrane may have the role of an endogenous protonophore in regulating andpartitioning energy transduction and heat production, as well as in pathogenesis of mitochondrialdiseases, aging, and apoptosis. The present article summarizes the supporting experimentalevidence obtained in this laboratory and presents a brief description of the theoretical basisof this model
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018650103259
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Hexokinase Binding to Mitochondria: A Basis for Proliferative Energy Metabolism (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 331-338 
    Details
    ISSN: 1573-6881
    Keywords: Cancer ; proliferation ; Crabtree effect ; insulin action ; compartmentation ; aerobic glycolysis ; hexokinase ; mitochondria ; porin ; protein synthesis ; TCA cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Current thought is that proliferating cells undergo a shift from oxidative to glycolytic metabolism, where the energy requirements of the rapidly dividing cell are provided by ATP from glycolysis. Drawing on the hexokinase–mitochondrial acceptor theory of insulin action, this article presents evidence suggesting that the increased binding of hexokinase to porin on mitochondria of cancer cells not only accelerates glycolysis by providing hexokinase with better access to ATP, but also stimulates the TCA cycle by providing the mitochondrion with ADP that acts as an acceptor for phosphoryl groups. Furthermore, this acceleration of the TCA cycle stimulates protein synthesis via two mechanisms: first, by increasing ATP production, and second, by provision of certain amino acids required for protein synthesis, since the amino acids glutamate, alanine, and aspartate are either reduction products or partially oxidized products of the intermediates of glycolysis and the TCA cycle. The utilization of oxygen in the course of the TCA cycle turnover is relatively diminished even though TCA cycle intermediates are being consumed. With partial oxidation of TCA cycle intermediates into amino acids, there is necessarily a reduction in formation of CO2 from pyruvate, seen as a relative diminution in utilization of oxygen in relation to carbon utilization. This has been assumed to be an inhibition of oxygen uptake and therefore a diminution of TCA cycle activity. Therefore a switch from oxidative metabolism to glycolytic metabolism has been assumed (the Crabtree effect). By stimulating both ATP production and protein synthesis for the rapidly dividing cell, the binding of hexokinase to mitochondrial porin lies at the core of proliferative energy metabolism. This article further reviews literature on the binding of the isozymes of hexokinase to porin, and on the evolution of insulin, proposing that intracellular insulin-like proteins directly bind hexokinase to mitochondrial porin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022442629543
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Spin dynamics by inelastic neutron scattering in YBCO (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 377-382 
    Details
    ISSN: 1573-7357
    Keywords: 74.20.Mn ; 25.40.Fq ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Key features of Inelastic neutron scattering experiments in YBCO-based cuprates are discussed. We underline the importance of precise oxygen content determination in samples having similar TC as well as the resolution configuration used. This may explain the apparent contradictory results recently obtained by different groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768415
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    c-axis infrared reflectivity of magnetically aligned YBa2Cu3O7−δ as a function of doping (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 773-778 
    Details
    ISSN: 1573-7357
    Keywords: 78.30.Hv ; 74.72.Bk ; 74.25.Gz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dense polycrystalline samples of YBa2Cu3O7−δ with a high degree of c-axis texture in the plane of the sample were prepared by magnetic alignment. The c-axis infrared reflectivity was measured between 300 and 6K on polished surfaces. Spectra compare well with measurements on single crystals indicating that magnetically aligned samples are a reliable alternative to single crystals for c-axis measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768477
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Macroscopic symmetry group describes Josephson tunneling in twinned crystals (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 483-488 
    Details
    ISSN: 1573-7357
    Keywords: 74.20.De ; 74-50.+r ; 74.72.Bk ; 74.62.Bf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A macroscopic symmetry group describing the superconducting state of an orthorhombically twinned crystal of YBCO is introduced. This macroscopic symmetry group is different for different symmetries of twin boundaries. Josephson tunneling experiments performed on twinned crystals of YBCO determine this macroscopic symmetry group and hence determine the twin boundary symmetry (but do not experimentally determine whether the microscopic order parameter is primarily d- or s-wave). A consequence of the odd-symmetry twin boundaries in YBCO is the stability of 1/2 Φo vortices at the intersection of a twin boundary and certain grain boundaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768432
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Fluctuation-induced in-plane magnetoconductivity in bilayered superconductors (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 681-686 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Fy ; 74.25.Ha ; 74.40.+k ; 74.50.+r ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper we summarize some of our theoretical results for the paraconductivity and for the fluctuation-induced in-plane magnetoconductivity in the weak magnetic field limit of layered superconductors with several interlayer separations. Also, we briefly discuss the existing experimental data obtained in untwinned Y Ba2Cu3O7-δ crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768463
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Zn-substitution effects on the normal optical conductivity and the superconducting gap (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 743-748 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk ; 74.25.Gz ; 74.62.Dh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Zn-substitution effects on the c-axis optical spectra have been investigated for highly oxygenated YBa2 Cu3Oy crystals with y = 6.88 – 6.92. In the normal state, the Zn-substitution does not affect the high frequency conductivity but changes the ω-dependence of the scattering rate at low frequencies, leading to the increase in the dc resistivity in the c-direction. In the superconducting state, we observed a pronounced effect of Zn-substitution that a large number of unpaired carriers form a Drude-like absorption band within the gap, keeping the maximum gap amplitude unchanged. The missing area which gives the superfluid density is found to correlate with Tc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768472
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Optical study of the Zn-substitution effect on phonon anomalies and spin gap in underdoped YBa2Cu3Oy (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 779-784 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Gz ; 74.72.Bk ; 78.30.Er ; 63.20.Kr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Performing optical reflectivity measurements with the electric field vector parallel to the c-axis of Zn-substituted, oxygen deficient YBa2Cu3Oy single crystals, we find a strong Zn-substitution effect on the anomaly of the inplane oxygen bending mode at 320 cm−1 and the new absorption band at 450 cm−1, which are observed in underdoped, non-substituted crystals. Contrary to that, the low-frequency suppression of the conductivity is almost not affected. We conclude that the phonon anomaly and the absorption band are related to each other, but that the suppression of the conductivity is an independent phenomenon. Moreover, the present work could be strong evidence for a model where some phonons couple to antiferromagnetic fluctuations at the (π, π)-point leading to anomalous behaviour of these phonons when a spin gap opens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768478
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Melting of the flux line lattice observed by specific heat experiments in YBa2Cu3O7−δ (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1099-1104 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Bt ; 74.60.Ge ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High resolution adiabatic specific heat experiments on YBa2Cu3O7−δ (0≤δ≤0.05) are performed in magnetic fields from 0 to 14 T (B∥c and B⊥c). In a 0.3 gram, twinned crystal with strong pinning, a step is consistently observed at the melting temperature Tm of the vortex solid up to a critical point that depends on δ. The field Bm and step temperature Tm obey the relation Bm=Bmo(δ)(1−Tm/Tc)≈4/3. The anisotropy of Bm and that of the upper critical field Bc2 are found to be equal. Alternatively, in a 18 mg, twinned crystal of high purity with low pinning, first-order-like specific heat peaks are observed on the melting line from 8 to 14 T. The entropy under these peaks is ≈0.5 kB /vortex/bilayer. These characteristic features are attributed to the melting of a vortex glass in the former case and that of a vortex lattice in the latter case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753846
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Gap symmetry and intrinsic intraplane pinning of untwinned YBa2Cu3O7 single crystals (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1165-1170 
    Details
    ISSN: 1573-7357
    Keywords: 76.60.Ge ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The interplane (cb) and intraplane (ab) anisotropy of untwinned YBa2 Cu307 single crystals has been investigated by means of the torque magnetometry. To extract the reversible and irreversible components, the torque was measured as a function of increasing angle as well as decreasing angle. The interplane irreversible torque Γirr shows two-fold peaks at θc =90 ° and270 ° (of half width11 ° at77 K) due to the well-known intrinsic interplane pinning. A novel intrinsic pinning has been discovered in the intraplane irreversible torque, i.e., Γirr shows four-fold peaks of half width20° at77 K when θa =0 °, 90 °, 180 ° and270 °. We argue that the intrinsic intraplane pinning comes from the four-fold nature of the gap parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753857
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Energy gap symmetry and thermal conductivity of YBa2Cu3O7 (1997)
    Springer
    Journal of low temperature physics 107 (1997), S. 467-472 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Fy ; 74.72.Bk ; 74.25.Jb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The characteristic enhancement in the heat conduction below Tc is analyzed on sintered YBa2Cu3O7 from viewpoints of both d-wave and s-wave coupling. Assuming the existence of a large energy gap Δ0(≥1.5Δ BCS ), only d-wave coupling is consistent with experimental observation. It is found that the most reasonable explanation for the enhancement is provided by the weak-coupling phonon conduction model under d-wave energy gap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397228
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Evidence for vortex lattice melting and softening in untwinned YBa2Cu3O7 single crystal (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1171-1176 
    Details
    ISSN: 1573-7357
    Keywords: 74.60.Ge ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Real part of the ac susceptibility X′1 of an untwinned YBa2 Cu3O7 single crystal jumps at the onset temperature in the narrow width (0.1 K in 0.7 T), suggesting the first-order melting transition. A sharp X′1 dip and a sharp X″ peak can be interpreted as synchronous trapping of vortices due to lattice softening prior to melting. At lower temperatures, the X′1-X″1 chart shows a single-parameter behavior while the melting occurs as a strong deviation from this.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753858
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Effect of correlated and point-like disorder on transport properties of YBa2Cu3O7−δ single crystals (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1177-1182 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Fy ; 74.40.+k ; 74.60.Ge ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Pinning by point-like defects and twin boundaries in single-crystalline YBa2Cu3O7−δ has been investigated by measuring resistance and current-voltage characteristics in fields up to 5 T. A number of untwinned and twinned samples with different densities of point-like defects were studied. The experimental results are compared within the framework of vortex-entanglement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753859
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Photodoping and relaxation of persistent photoconductivity in YBa2Cu3Ox studied byin-situ transport measurements (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1403-1408 
    Details
    ISSN: 1573-7357
    Keywords: 73.50.Jt ; 73.5O.Pz ; 74.72.Bk ; 74.76.Bz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on in-situ resistivity and Hall-effect studies of partially oxygen-depleted YBa2Cu3Ox thin films during white light illumination. The measurements were performed at various temperatures between the superconducting transition and room temperature. At all temperatures the resistivity and the Hall coefficient decreased as a function of the illumination time. The Hall number pH and the Hall mobility μH, calculated within a simple one-band model, showed an increase of pH during the illumination without a saturation. At low temperatures, μH behaved similarly to pH. At 200 K, however, μH became constant after several hours of illumination, while at 260 K and 290 K, we observed a short increase of μH followed by a long-term decrease. From the different time dependences of μH and pH, we conclude that two mechanisms contribute to the photodoping effect. Additionally, we observed that after termination of the illumination at 290 K the photodoped values of pH and μH relaxed with substantially different time constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753896
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Scanning tunneling spectroscopy studies on YBa2Cu3O7−δ (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1129-1134 
    Details
    ISSN: 1573-7357
    Keywords: 74.60.Ge ; 71.20.−b ; 74.50.+r ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Scanning Tunneling Spectroscopy (STS) measurements have been carried out on the high Tc superconductor (HTS) YBa2Cu3O7−δ (YBCO). Using very high quality single crystals as well as hard tips, we obtained differential conductance spectra which showed various conductance features in agreement with other spectroscopic techniques. The reproducibility of our spectra allowed us to map for the first time the vortex lattice on a HTS using a STS technique1. The vortices are arranged in a short range order oblique lattice, while the cores of the flux lines show an anisotropic shape. These observations can be related to the in-plane anisotropy of YBCO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753851
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Novel vortex dynamics in untwinned YBa2Cu3O7−δ single crystals (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1147-1152 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Fy ; 74.40.+k ; 74.60.Ge ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Magnetotransport measurements on a clean, untwinned YBa2Cu3O7−δ single crystal show that the vortex dynamics at temperatures just below the vortex lattice melting transition are highly dependent on the type of modulation of the probing current. While in the case of DC current the flux flow is disordered, the “shaking” of the vortex lattice by a square-wave current leads to a more uniform vortex motion. A small asymmetry (∼10%) in the durations of the positive and negative parts of the square-wave period induces periodical oscillations of the voltage response amplitude. The period of oscillations (∼100 s) is the same order of magnitude as the time needed for vortices to cross the sample (transit time). We relate the observed voltage oscillations to a periodically ordered vortex motion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753854
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Phase sensitive measurements of the pairing state symmetries of cuprate superconductors using tricrystal microbridges (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 527-532 
    Details
    ISSN: 1573-7357
    Keywords: 74.50.+r ; 74.72.Bk ; 74.76.Bz ; 85.25.Cp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the field-modulated critical currents of cuprate thin film microbridges on tricrystal substrates are reported. Two central peaks of equal height are observed in the field-dependent critical currents of YBCO tricrystal microbridges. However, the critical current is nonvanishing at zero field for YBCO, consistent with an orthorhombically distorted d-wave order parameter. An ion-irradiated YBCO tricrystal microbridge has also been measured, and has been found to exhibit more ideal dx2−y2-like behavior with increasing irradiation dosage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768439
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Preparation of long Y123 superconducting filament by solution spinning (1996)
    Springer
    Journal of low temperature physics 105 (1996), S. 1421-1426 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk ; 74.60.Jg ; 74.80.Bj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The preparation of a long superconducting Y123 filaments is developed by using solution spinning for the precursor of the oxide. Long precursor filaments are prepared by dry spinning with a starting homogeneous aqueous PVA solution containing Y, Ba and Cu acetates. The as-drawn filament with 250 μm in diameter and 300 mm in length is pyrolyzed and partial-melted by using a tube furnace with a constant heating zone of 500 mm. A superconducting filament of 60 μm in diameter and 200 mm in length with high Jc of more than 104A/cm2 at 77 K and 0 T is obtained by controlling the partial melting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753899
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Determination of pairing symmetry using phase-sensitive tunneling in tricrystal cuprates (1997)
    Springer
    Journal of low temperature physics 107 (1997), S. 445-454 
    Details
    ISSN: 1573-7357
    Keywords: 74.72.Bk ; 74.60. Ge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An unambiguous determination of the pairing symmetry in cuprate superconductors is important in order to understand the origin of high-temperature superconductivity. By making use of the effects of pair tunneling and flux quantization, we have designed and implemented several tricrystal experiments for phase-sensitive determination of the order parameter symmetry in high-Tc superconductors such as YBa2Cu3O7 Tl2Ba2CuO6, GdBa2Cu3O7, and Bi2Sr2CaCu2O8. By using a high-resolution scanning SQUID microscope, we have made the first direct observation of spontaneously generated half-flux quanta at the tricrystal point. The half-integer flux quantum effect in various specially designed tricrystal cuprate systems provides strong evidence for d-wave pairing in high-Tc cuprates. Our various tricrystal experiments have demonstrated that this effect can be used as a general probe of the microscopic phase of the pair wavefunction in unconventional superconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397226
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Non-isovalent alkali metal “substitution” in YBa2Cu3O7−y granular ceramics (1995)
    Springer
    The European physical journal 96 (1995), S. 319-324 
    Details
    ISSN: 1434-6036
    Keywords: 74.72.Bk ; 74.62.Bf ; 74.72.Dh ; 74.25.Fy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The aim of this paper is to study the influence of non-isovalent “doping” in YBa2Cu3O7−y in particular on its synthesis conditions and on the resistive properties both with and without a magnetic field. We concentrate on the study of possible alkali ions (Na, K, Cs) “substitution” at the barium sites. A low temperature sintering process is used in order to induce a reactive liquid phase. The final chemical composition is discussed as a function of the amount of the liquid phase. No alkali ion is substituted. Carbonate layers are present. However, this (lack of) “substitution” leads to induced vacancies and improved electrical transport properties which are as good as in highly pure materials. For conciseness the case of Na “substitution” only is illustrated. The use of such data in order to probe the microstructure is emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313053
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Anisotropic magnetoresistance in the normal state of oxygen-deficient YBa2Cu3O7−δ thin films induced by superconducting fluctuations (1995)
    Springer
    The European physical journal 98 (1995), S. 453-456 
    Details
    ISSN: 1434-6036
    Keywords: 74.25.Fy ; 74.40.+k ; 74.72.Bk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated both the transverse and the longitudinal magnetoresistance of oxygen-deficient YBa2Cu3O7−δ thin films above their critical temperatureT c =55 K. The magnetoresistance is solely caused by the magnetic-field suppression of superconducting orderparameter fluctuations, existing in the films up to 143 K, i.e. 2.6T c . The fluctuation effect provides a reliable determination of the Ginzburg-Landau coherence lengths, ξ ab = 2.5 nm and ξ c = 0.09 nm, with the anisotropy enhanced by oxygen depletion. No signature of the Maki-Thompson fluctuation process or a magnetoresistance resulting from the cyclotron motion of the normalstate quasiparticles was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01320845
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    An alternative approach to electrochemistry (1995)
    Springer
    Journal of statistical physics 78 (1995), S. 513-529 
    Details
    ISSN: 1572-9613
    Keywords: Donnan potential ; electric potential ; electrochemical cell ; external electric work ; liquid junction potential ; mitochondria ; Onsager reciprocal relations ; operational quantities ; single-ion chemical potential ; state function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The concepts used conventionally in electrochemistry, single-ion chemical potential and electrostatic potential difference, are not obtainable from measurements in an inhomogeneous system. The use of nonoperational and mutually dependent forces in flux equations has impeded our understanding of electrochemical processes, and has led to wrong conclusions. The equation for entropy production is derived using only operationally defined quantities, chemical potentials of neutral components and the electric potential measured with reversible electrodes. The electric potential enters calculations as external electric work in the first law of thermodynamics. From entropy production, flux equations are obtained where the forces are operationally defined, measurable quantities. Three different problems from electrochemistry are discussed, the liquid junction potential, the Donnan potential, and energy coversion in mitochondria. The conventional method of calculations and the operational method are compared. The operational method permits more detailed calculations of emf, and an understanding of the process from a different approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183362
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...