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  • 1
    Electronic Resource
    Electronic Resource
    Distribution of iron over copper sets in GdBa2(Cu1−xFex)3O7−δ (abstract) (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5082-5082 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Iron-doped compounds GdBa2(Cu1−xFex)3O7−δ with 0.03≤x≤0.25 and δ〈0.1 as well as with δ〉0.7 have been investigated by Mössbauer spectroscopy with 155Gd and 57Fe. For each iron concentration x, samples with different transition temperatures Tc (at constant oxygen content, δ〈0.1) were prepared and investigated. Samples were reduced to an oxygen deficiency δ〉0.7 either at 650 °C under vacuum or at 950 °C in a N2 atmosphere, followed by a quench to room temperature. A comparison of 57Fe Mössbauer spectra for samples treated by these different procedures has yielded an unambiguous determination of the fraction of iron atoms occupying Cu(2) sites. This fraction extrapolates to ∼4% for x→0. It increases monotonously with x to ∼17% for x=0.12. In samples reduced at 950 °C for 44 h, the fraction of iron on Cu(2) sites is doubled, and this large Cu(2) site occupancy is maintained when the material is reoxidized at 450 °C. From the systematic variation of the parameters associated with the remaining quadrupole doublets with iron concentration x and with Tc (for constant x), tentative assignments of the doublets to specific oxygen coordinations of Fe on Cu(1) sites were derived. For 155Gd, both the quadrupole splitting and the isomer shift vary smoothly with iron concentration. No influence of an extra charge associated with iron on Cu(2) sites in the vicinity of Gd nuclei is discernible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344678
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  • 2
    Electronic Resource
    Electronic Resource
    Crystal fields and exchange interactions in Yb2Fe17: A 174Yb Mössbauer study (abstract) (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4625-4625 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Most rare-earth -(R) iron compounds R2Fe17 crystallize in the hexagonal Th2Ni17 structure with two inequivalent rare-earth sites in the unit cell. For Tm2Fe17 magnetic anisotropy of opposite character has been determined for the two Tm sites.1 Nevertheless, the axial anisotropy of one Tm site dominates at low temperatures and forces the magnetic moments to the direction parallel to the c axis below the spin-reorientation temperature TSR=74 K. Magnetization measurements on Yb2Fe17 gave no indication for a spin reorientation.2 In this compound, the Fe sublattice anisotropy seems to dominate at all temperatures, confining the moments to the plane perpendicular to the c axis. This has now been confirmed by 174Yb Mössbauer spectra of Yb2Fe17 in the temperature range 1.6–100 K. The different crystal fields acting on the Yb 4f shell at the two sites lead to a large difference in the static moments as revealed by the different hyperfine fields. From the temperature dependence of the magnetic and electric hyperfine interactions, values for the crystal-field parameters and exchange fields at both Yb sites have been derived. Structural disorder, probably due to random occupation of Yb sites by Fe2 dumbbells, leads to distributions of the crystal-field parameters and to considerable broadening of the Mössbauer spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344833
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  • 3
    Electronic Resource
    Electronic Resource
    Rotor dynamics of superconducting magnetic bearings (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 1254-1256 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A two dimensional proximity sensor system was used to study dynamics and magnetic unbalance effects of superconducting magnetic bearings. Both dynamic stiffness and vibration damping were found to increase with decreasing bearing gap. Lateral vibrations of an aluminum disk integrated into a superconducting flywheel system were measured during free rotation. From the measurements, the magnetic unbalance was deduced and it is shown that related effects, such as bearing losses and instability at the critical, can be reduced significantly by shifting the center of gravity of the disk assembly towards the magnetic symmetry axis. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362867
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  • 4
    Electronic Resource
    Electronic Resource
    Magnetic order in Yb"2Fe"1"7 studied by magnetization measurements and by ^1^7^4Yb Mossbauer spectroscopy
    Amsterdam : Elsevier
    Solid State Communications 71 (1989), S. 759-763 
    Details
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1098(89)90081-1
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  • 5
    Electronic Resource
    Electronic Resource
    A study of crystal fields in Yb"2Fe"1"4B by ^1^7^4Yb Mossbauer spectroscopy
    Amsterdam : Elsevier
    Solid State Communications 69 (1989), S. 83-86 
    Details
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1098(89)90031-8
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  • 6
    Electronic Resource
    Electronic Resource
    A ^1^5^5Gd Mossbauer study of exchange interactions in Gd"2Fe"1"4B
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 80 (1989), S. 23-26 
    Details
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0304-8853(89)90317-X
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  • 7
    Electronic Resource
    Electronic Resource
    Nicht-invasiver Nachweis intraokularer Veränderungen mit einer Gamma Szintillationskamera (1979)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 211 (1979), S. 187-203 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird ein nuklearmedizinisches Verfahren zum nicht-invasiven Nachweis intraokularer Veränderungen vorgestellt. Eine Gamma Szintillations-Kamera mit nachgeschalteter Meßdatenverarbeitung dient als Untersuchungsinstrument. Ein Doppel Lochblenden-Kollimator entwirft für jedes Auge getrennt ein vergrößertes Abbild der Radioaktivitätsverteilung auf dem Detektor-Kristall der Kamera. Dieser Sonderkollimator wurde speziell für nuklearmedizinische Untersuchungen der Augen entworfen. Konstruktive Einzelheiten werden geschildert und die wesentlichen Abbildungsparameter des Gerätes — Auflösung und Ausbeute — anhand von Phantomversuchen erläutert.
    Notes: Abstract A gamma scintillation camera is used for noncontact detection of intraocular mass lesions. A double aperture pinhole collimator was designed for this special application. The collimator projects a magnified image of the radioactivity present in each, eye onto the detector crystal of the camera. Details of the collimator design are described. The image-making properties of a double aperture pinhole collimator for ocular, scintigraphy in regard to resolution and response were studied and demonstrated by phantom experiments. So far we have studied 50 cases with this new nuclear medicine procedure, using mainly technetium-pertechnetate as the radioindicator. Case histories and records of some typical results are presented. Better designed radiopharmaceuticals with appropriate tumor-seeking properties should be developed. Labeled melanin precursors are promising for detection of these lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02387424
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  • 8
    Electronic Resource
    Electronic Resource
    Digitale Szintigraphie des Ohres (1981)
    Springer
    European archives of oto-rhino-laryngology and head & neck 231 (1981), S. 689-691 
    Details
    ISSN: 1434-4726
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Description of a new nuclear medical method permitting the application of radioisotopes for otologic diagnosis. It is made possible by use of an specially constructed pinhole collimator for the Anger-camera. The evaluation is done by aid of a special Fortran IV computer program. For the ear scintigraphy the bone-seeking radiopharmacon 99mTc-MDP is applied, and, thus, patients suffering from operatively confirmed otosclerosis exhibit hot spots of the radioisotope in the regions of the oval and the round window or of the cochlea respectively. This method, for the first time, enables in vivo studies of the metabolic activity of otosclerotic foci in all the bony labyrinthine wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501705
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  • 9
    Electronic Resource
    Electronic Resource
    Cochleomeatal scintigraphy — a new tool in modern neuroradiological diagnosis of acoustic neuroma (1984)
    Springer
    Neuroradiology 26 (1984), S. 107-111 
    Details
    ISSN: 1432-1920
    Keywords: Scintigraphy ; CT ; acoustic neuroma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cochleomeatal scintigraphy (CMS) and CT or air CT cisternography are today the methods of choice for the detection or exclusion of a neurootologically suspect acoustic neuroma. Whereas CT as a morphological method of investigation provides better preoperative information, CMS is likely to be superior to CT as a functional investigation technique in relapse diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00339857
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  • 10
    Electronic Resource
    Electronic Resource
    Why does apomorphine fail in Weddell seals? (1997)
    Springer
    Polar biology 17 (1997), S. 188-190 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The emetics apomorphine hydrochloride and emetine dihydrochloride were tested on Weddell seals (Leptonychotes weddellii) to obtain stomach contents for dietary studies. The drugs prostaglandin F2α, carbachol, and hydergine, which have emetic side effects, were also used. None of the drugs induced regurgitation and possible reasons for this are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050121
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