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  • Articles  (57)
  • Springer  (57)
  • 1980-1984  (24)
  • 1975-1979  (33)
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  • Articles  (57)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 39 (1980), S. 115-124 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Magnetic and electric hyperfine interactions in the system EuSm were investigated with the isomeric 11/2− state in145Eu by applying the time-differential perturbed angular distribution (TDPAD) method. The temperature dependence of paramagnetism was studied between 90 K and 1000 K by measuring the magnetic hyperfine interaction frequency ωL=gNμNħ1 β(T)Bext. The paramagnetic correction factor β strictly follows the Curie-Weiss relation β=1+C/(T-θ), withC=−50(2) K and θ=−29(5) K. This is compatible with a hyperfine field ofB int(0)=−25(1) T, a valence of two for Eu in Sm, and antiferromagnetic order at low temperatures. The temperature dependence of the electric quandrupole coupling constant vQ, investigated between 100 K and 400 K, can be reproduced by a linear temperature variation vQ(T)=vQ(0) (1-AT), with vQ(0)=16.2(4) MHz andA=7.2(8)·10−4 K−1. The paramagnetic relaxation time τrel of the nuclear alignment is proportional to the temperature of the sample, with τrel T−1=3.7(2) ·10−9s K−1. This leads to the Korringa relation τJ T=const=5.1(5)·10−11s K for the relaxation time of the 4f electronic spinJ. Assuming that the relaxation ofJ is mainly caused by exchange interaction between conduction electrons and localized 4f electrons at the Eu site, an exchange integral of |J eff|=0.10(2) eV can be deduced.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 13 (1978), S. 275-281 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé Le nitrate d'ammonium était chauffé et refroidi pas à pas dans un four fixé sur un goniomètre de rayons X. A chaque température, des diagrammes de diffraction étaient mesurés par un détecteur semiconducteur, combiné avec un sélecteur multicanaux. Les résultats supportent l'existence d'une phase IF. Ils montrent, que la transition des modifications IV/III procède par une phase de transition, qui ressemble à la phase II'.
    Abstract: Zusammenfassung Ammoniumnitrat wurde in einer Hochtemperaturkammer auf einem Röntgengoniometer schrittweise aufgeheizt und abgekühlt. Bei jeder Temperatur wurde ein Beugungsdiagramm aufgenommen mit einem Si-Li-Detektor und angeschlossenem Vielkanalanalysator. Die Ergebnisse unterstützen die Annahme einer Phase II'. Sie zeigen, daß die Phasenumwandlung IV/III über einen Übergangszustand verläuft ähnlich oder identisch mit der Phase II'.
    Notes: Abstract Ammonium nitrate was heated and cooled in consecutive steps in a high temperature device mounted on a X-ray goniometer. Diffraction patterns were measured at each temperature, using a Si-Li detector together with a multichannel analyzer. The results strongly support the existence of a phase II'. They show that the phase change IV/III goes via a transition state similar to or consistent with phase II'.
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  • 3
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The g-factors of the 11/2− states in145, 147, 149Eu were measured by the TDPAD method in metallic Sm-targets. The temperature dependence of the paramagnetism in the system145EuSm follows strictly a Curie-Weiß law Beff=B0[1+¯C/(T-θ)] with C=−50(2)K and θ=−29(5)K. Extrapolation to T→∞ yields g(145Eu)=+1.356(8), g(147Eu)=+1.28(1) and g(149Eu)=+1.27(5). In addition, the quadrupole coupling constantν Q=12.5(5) MHz, and a lower limit for the paramagnetic relaxation time τ = 1 us was determined at room temperature for the 11/2− state of145Eu in Sm. Extensive studies of the anomaly of magnetic moments in the vicinity of the closed neutron shells N=50 and N=126 have unambiguously revealed an anomaly of the proton gl factor of δgl≈0.1 [1]. In the present letter we report on a similar investigation for the closed neutron shell N=82. For this purpose the g-factors of the first excited 11/2− states in the rare earth isotopes145, 147, 149Eu were measured. Due to paramagnetic effects, a measurement of nuclear g-factors in the rare earth region requires the investigation of the paramagnetic behaviour of the probe atoms in the chosen target material. The g-factors in145,147,149Eu were measured by the method of the time differential perturbed angular distribution (TDPAD) of the deexcitationγ-rays. The 11/2− states in145Eu(EX=716 keV, T1/2=0.49 gms) and in149Eu(EX=497 keV, T1/2=2.43 μs) were populated and aligned by the nuclear reaction144,148sm(d,n)145,149Eu with the pulsed deuteron beam (Ed=11 MeV) of the Erlangen tandem accelerator. Enriched metallic Sm targets of 89%144Sm and 95%148Sm were used. The 11/2− state in147Eu(EX=625 keV, T1/2=0.77 μs) was excited by the reaction147Sm(p,n)147Eu with a pulsed proton beam (Ep=10 MeV) using a 93% enriched147Sm target. A detailed description of the experimental set-up and the evaluation procedure for the present TDPAD measurements is given in ref. [2]. The deexcitation γ-rays of the isomeric Eu states were detected by two NaJ(T1) detectors encompassing an angle of Δθ=90°, and placed in a plane perpendicular to the external applied magnetic field direction. The magnetic field was calibrated by measuring the very precisely known g-factor of the isomeric 5/2+ state of19F in a BaF2 target. The Sm targets were mounted either in an oven for the high-temperature measurements or into a copper cooling-rod for temperatures down to liquid nitrogen.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 291 (1979), S. 49-52 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Theg-factor of the first excited state in the odd-odd nucleus138La (E x=73 keV,I π,T 1/2=116 ns) was measured by the time-differential perturbed angular distribution (TDPAD) method. The result, corrected for Knight shift and diamagnetic shielding, isg=+0.962±0.016. This value can be fairly well reproduced using the additivity relation for magnetic moments, empirical values for the odd-proton and odd-neutrong-factors, and an experimentally deduced wave function for the 3+ state.
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  • 5
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The concentration and temperature dependence of the quadrupole hyperfine interaction of111Cd in InTl (hcp),InPb (fct),InTl (fct) andInCd (fct and fcc) alloys were studied using the perturbed angular correlation technique. The change in the observed quadrupole interaction frequency with concentration can be described by a linear dependence on the axial ratioc/a in all cases. In the alloys with identical crystal structures the strength of thec/a dependence is independent of the solute, in contrast to the strength of the concentration dependence. In all cases where no phase transition occurs, the change in the electric field gradient with temperature follows the empirical relationV zz (T)=V zz(0) · (1−B·T 3/2), where the coefficientB depends on the lattice structure, on the solute-solvent combination and on the concentration. The phase transitions ofInCd alloys at 293 K could clearly be seen as discontinuities in the temperature curves. A similar series of discontinuities observed around 116 K suggests the existence of a cubic low temperature phase.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 33 (1977), S. 689-690 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rat ovary is insensitive to luteinizing hormone and human chorionic gonadotrophin till to the 8th to 10th day of postnatal development. This insensitivity is due to the lack of a specific hormone receptor.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 37 (1981), S. 1274-1276 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary DNA sequence interspersion was investigated in pheasant and pelican nuclear DNA. As is typical for birds, these genomes are organized in a long period pattern. Altogether, 5 bird species with genome sizes between 1.6 and 1.9 pg DNA are compared with regard to the extent of repetitive and single copy sequence interspersion. The result indicates that the average length of interspersed repetitive sequences increases with genome size.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 32 (1976), S. 27-28 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Genic activity in tetraploid members of the amphibian speciesOdontophrymus americanus is reduced to that of diploid ones. Loss of ribosomal genes, a mechanism suggested by others as a means of decreasing genetic activity, could be ruled out. The diploids and the tetraploids have almost identical proportions of their genomes complementary to (28s+18s) ribosomal RNA.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 33 (1977), S. 1394-1396 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The delay of puberty onset in female rats adrenalectomized before the 25th day of age is due neither to changes in the number of ovarian HCG-receptors nor to an altered hormone affinity of these receptors. It is assumed that glucocorticoids act on an intracellular level, in the ovarian cells, possibly by alterations of cyclic AMP-dependent phosphodiesterase activity.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 33 (1977), S. 1397-1398 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hemigonadectomy in 9-day-old female rats results in a drastic increase in the weight and the number of HCG-binding sites of the remaining ovary during further development. However, on a per mg basis of ovarian weight, the number of HCG-receptors is identical in hemicastrated and control rats.
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