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  • Inorganic Chemistry  (19)
  • 23.40.Hc  (4)
  • locomotion  (3)
  • EPR  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of superconductivity 13 (2000), S. 895-897 
    ISSN: 1572-9605
    Schlagwort(e): EPR ; YBCO ; rare-earth ions ; impurities
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract The first observation of electron paramagnetic resonance (EPR) of Tb3+ doped into YBa2Cu3O6 is reported. EPR is used to determine the local symmetry of the rare-earth ion and to study the effect of suppression of high-T c superconductivity by doping. The distance between the lowest singlets of Tb3+ ion Δ ≅ 7.1 GHz ≡ 0.24 cm−1 and g-factor g ∥ ≃ 17.9 have been estimated from measurements. Both these parameters are in a good agreement with the corresponding calculated values. No evidence of Tb4+ ions was found.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1572-9605
    Schlagwort(e): EPR ; LSCD ; isotope effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract The electron paramegnetic resonance (EPR) of Mn2+ doped into La2−x Sr x CuO4 was used to probe the copper spin relaxation via the bottleneck effect for oxygen isotope (16O and 18O)–substituted samples. It was found that the EPR linewidth is larger for the 18O isotope samples than for the 16O samples. For x = 0.03, the linewidth for the 18O sample is larger than for 16O sample by a factor of 2. The isotope effect is pronounced at low temperatures and decreases with increasing Sr concentration. This effect is quantitatively explained by the Cu2+ S = 1/2 spin relaxation to the lattice via Dzyaloshinski terms coupled linearly to the local Q 4/Q 5 tilting modes of the CuO6 octahedra as proposed by Kochelaev et al. [1] The Q 4/Q 5 modes are coupled sterically to the Q 2 Jahn–Teller modes considered to be relevant for the (bi)-polaron formation and thus for the high-temperature superconductivity (HTSC).
    Materialart: Digitale Medien
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  • 3
    ISSN: 1434-601X
    Schlagwort(e): 23.40.Hc ; 21.10.Dr ; 21.10.Pc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Within the framework of a systematic study of 0+→1+ Β-transitions in the100Sn region, the decay of the neutrondeficient isotope102Cd was investigated. This isotope was produced in16O+92Mo and58Ni+50Cr heavy-ion reactions and in proton-induced spallation ofnatSn, and mass-separated samples were prepared by means of the GSI and the ISOLDE on-line mass separators, respectively. Observations of X-rays,γ-rays, and conversion-electrons studies have led to an improved102Cd→102Ag decay scheme which includes six 0+→1+ Gamow-Teller transitions. The half-life of102Cd was redetermined with higher accuracy to be 345±8 s. Using a Si(Li)-BGO-Ge spectrometer, theΒ + endpoint energy of the main decay component was measured, yielding aQ EC value of 2587±8 keV. This very small uncertainty ofQ EC, combined with the improved knowledge of half-life and decay scheme, allows an accurate determination of the observed Gamow-Teller decay strengthB Σ (GT)=1.513±0.055 for102Cd. This result is discussed in comparison with predictions from model calculations.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Tg ; 23.40.Hc ; 21.60.Cs ; 27.20.+n
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Beta-coincidentγ-rays have been measured from implanted pure samples of12Be separated at the LISE3 spectrometer at GANIL. An intensity of 0.040(26) % can be estimated for the branching ratio of the isospin forbidden pure-Fermi transition to the 0+ excited state of12B and of 0.008(6)% of the transition to the 1−1 excited state. Both are taken to represent upper limits. The half-life has been re-measured to be 26.1(2.4) ms.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1434-601X
    Schlagwort(e): 21.10.Pc ; 21.10.Re ; 23.20.Lv ; 23.40.Hc ; 27.60.tj
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A high-sensitivityγ-spectroscopic study of the149Hoπh 11/2 andπs 1/2 β-decays using mass separated sources has located dominant 0+ → 1+ GT decay strength associated with decay of pairedh 11/2 protons, leading to 3п-states in the149Dy daughter nucleus. In theirγ-decay low-lying149Dy levels characteristic of anN=83 nucleus are excited. They include theνf 7/2,νp 3/2,νh 9/2 andνp 1/2 single particle- and theνs 1 2/−1 andνd 3 2/−1 two-particle one-hole states, as well as the νf 7/2 × 3− andνf 7/2 × 2+ particle-phonon multiplets. A synopsis is given of these excitations in theN=83 isotones from149Nd to153Yb. The149Dy GT decay strength is discussed in terms of the147Tb82 and148Dy82 decays. The strength function results are also compared with independent149Ho 11/2− decay data from the literature based on totalγ-ray absorption measurements.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1434-601X
    Schlagwort(e): 21.10.−k ; 23.40.Hc ; 27.60,+j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The EC/β+-decay of the odd-odd nucleus100Ag was studied by means of total absorptionγ-ray spectrometry. Most of the Gamow-Teller strength was found to be concentrated at an excitation energy of 5.6 MeV in100Pd, the FWHM of this resonance being 1.5 MeV. The measured strength distribution which is interpreted within the BCS approximation as being due to the dominant population of four-quasiparticle excitations, resembles the distribution predicted by an advanced shell-model calculation for the98Ag →98Cd decay.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 5 (1985), S. 447-461 
    ISSN: 0886-1544
    Schlagwort(e): chemokinesis ; orthokinesis ; klinokinesis ; polymorphonuclear leucocytes ; locomotion ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Evidence is presented to show that klinokinesis, which was previously demonstrated in bacteria and amoeba only, may also occur in metazoan cells. The chemotactic peptide formyl-Met-Leu-Phe (fMLP) elicited orthokinetic and klinokinetic responses of human blood-borne polymorphonuclear leucocytes (PMNs) under the test conditions used. Increased speed (orthokinesis) was due to an increase in the proportion of migrating cells as well as in the speed of the locomoting subset. The klinokinetic effect was manifested by a decrease in the klinolocomotion index, the mean angle of changes in direction ≥ 90°, and the frequency of turns ≥ 90°. The klinolocomotion index was inversely related to speed. This explains the synergistic effect of klinokinesis and orthokinesis in this system. Colchicine alone had and orthokinetic effect which was exclusively due to alterations in the proportion of migrating cells and it altered the turning behaviour without exerting a klinokinetic effect. However, colchicine had marginal orthokinetic and klinokinetic effects on fMLP-stimulated cells resulting in reduced translocation. The relationship between klinokinesis and mean angle or frequency of turns has been analysed. Klinokinesis was a substantial though not the major element of the chemokinetic response to fMLP under the conditions used. No other metazoan cells have been shown to possess such a complete pattern of responses, including orthokinesis, klinokinesis, and chemotaxis, which regulate locomotion.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 25 (1993), S. 10-18 
    ISSN: 0886-1544
    Schlagwort(e): microtubules ; blebs ; locomotion ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Colchicine-induced stimulation of polymorphonuclear leukocyte (PMN) locomotion is an interesting model because extension of blebs at the front occurs at a rate (about 2.4 μm/s) which is far above that reported for growth of actin filaments. The following cytoskeletal changes were observed in colchicine-treated PMNs: (1)a small increase in cytoskeleton-associated actin was noted, as well as a somewhate more pronounced increase in cytoskeleton-associated α-actinin, as compared with untreated or DMSO-treated controls. There was, however, no measurable increase in F-actin as determined by NBD-phallacidin blinding; (2)the values for the ratio (α-actinin/actin) are lower in PMNs treated with colchicine for 30 min, as compared with PMNs stimulated with fNLPNTL for 1 minute (non-polar ruffling cells) or 30 min (polarized locomoting cells); thus, this ratio may depend on the type of PMN motility; (3) in polarized PMNs F-actin was mainly located linearly all along the cell membrane; there was more intense staining at the front of the cells; (4) α-actining appeared to colocalize with F-actin at the leading front, but not with F-actin at the tail of polarized cells; (5) myosin was preferentially found at the rear part of polarized cells but not or only to a small extent at the front. Our data indicate a close functional correlation between microtubules and microfilaments. We speculate that F-actin in combination with α-actinin promotes expansion of pseudopods, whereas myosin combined with F-actin promotes contraction. In more general terms we suggest that different forms of PMN motility are generated by differential selective interaction of cytoskeletal compnents and variations in the composition of the cytoskeleton in different sites of the same cells. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 47-60 
    ISSN: 0886-1544
    Schlagwort(e): neutrophil granulocytes ; motility ; locomotion ; cell-shape ; cell-substratum adhesion ; f-Met-Leu-Phe ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Activation of the motile apparatus by chemokinetic factors cannot be reliably assessed in cells that are attached to a solid substratum because motility can be totally abolished by excessive adhesion. It is however, necesary to quantify the activation of the motile apparatus in order to analyze and understand chemokinetic responses.It was the purpose of the present work to establish morphological criteria that can be used to quantify motility in nonadherent (floating) neutrophils and to predict the locomotor response under conditions of limited adhesion. The proportion of neutrophils performing crawling-like movements (polarized cells) in suspension correlates very closely with stimulated locomotion at low to optimal concentration of f-Met-Leu-Phe, ie, under conditions of limited adhesion. Reduced locomotion at supraoptimal concentrations of f-Met-Leu-Phe has also morphological correlates. The major feature is the decrease in the proportion of neutrophils performing crawling-like movements and the corresponding appearance of cells that are motile but not polarized in suspension and that do not locomote on the substratum. Concentration-dependent changes in neutrophil length and in the proportion of polarized neutrophils with and without tail were also observed. The locomotor potential of neutrophils under conditions of limited contact with the substratum can be predicted on the basis of their motile behavior, in particular the proportion of cells showing crawling-like movements, in suspension. In combination with measurements of adhesion the procedure should permit a more complete analysis of the regulation of chemokinetic responses.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 272 (1953), S. 303-312 
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Es werden die RAMAN-Spektren von Trimethyl-, Tri-dimethylamino-, Trimethoxy-, Trichlor-boroxol und von B-Trimethylborazol mitgeteilt. Die Diskussion der spektralen Daten erbringt in Anlehnung an die gut untersuchten Spektren von 1,3,5-trisubstituierten Benzolen den sicheren Nachweis für einen ebenen Sechsring B3O3 in allen Boroxolverbindungen. Dieser liegt nach dem RAMAN-Spektrum auch im Dibortrioxyd vor.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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