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  • 1990-1994  (2)
  • 1985-1989  (4)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3343-3345 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous GdTbFe thin films were produced by dc magnetron sputtering in argon atmosphere at varying partial pressures of nitrogen, oxygen, and water. The compensation temperature Tcomp, the Curie temperature TC, and the uniaxial magnetic anisotropy constant Ku decrease strongly with increasing impurity concentration in the films. The influence of nitrogen on Tcomp and Ku is about a factor of 3 less than that of oxygen and water. The strong decrease of Tcomp and Ku is due to the preferred reaction of the impurities with the rare-earth (RE) atoms. This leads to a preferred deactivation of the latter resulting in a decrease of the rare-earth (RE) sublattice magnetization. Moreover, the uniaxial magnetic anisotropy is primarily based on the single ion anisotropy of the Tb atoms. If these are deactivated Ku decreases. At increasing impurity concentrations the selectivity of deactivation decreases and increasing amounts of Fe are affected. Thus, the steepest decrease of Tcomp and Ku is observed at low concentrations. For Tcomp the mean values of the slopes at concentrations below 1 at. % are 35 K per at. % for nitrogen, 85 K per at. % oxygen (Ar/oxygen atmosphere), or 125 K per at. % oxygen (Ar/water atmosphere). Ku is reduced to half its original value at concentrations of 4 at. % nitrogen, 1.2 at. % oxygen (Ar/O2), and 0.9 at. % oxygen (Ar/H2O) in the films. The Curie temperature TC decreases at a rate of about 10 K per at. % impurity. This is due to the diminishing magnetic interactions at increasing impurity incorporation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3331-3333 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GdTbCo films were rf diode sputtered from a composite target varying the argon pressure PAr and the substrate bias voltage Vb. Both the uniaxial magnetic anisotropy constant Ku and the aging behavior of the films depend strongly on the preparation parameters. The absolute maximum of Ku was obtained at Vb=−150 V. However, at this bias voltage nearly the highest oxidation rate of unprotected 100-nm-thick films was observed. Films of highest stability are obtained without any bias voltage. The oxidation rate is correlated with the Ar concentration in the films. It was argued recently that the anisotropy of sputtered films could depend on argon incorporation. Our results seem to rule out this mechanism since GdTbCo films prepared at zero bias show a relative Ku maximum in dependence on PAr where the argon concentration is near its absolute minimum. The magneto-optic Kerr rotation θK of the films can only be correlated with the Co concentration for zero bias films. Some additional variation depending on the bias voltage has been observed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 393-395 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed low-threshold lasing in a GaAs single quantum-well vertical microcavity. At 4 K the quantum-well emission linewidth is reduced, and the coupling efficiency β of the spontaneous emission to the lasing mode is improved. The laser threshold pump power obtained for a 200 A(ring) GaAs quantum well pumped by a continuous wave Ti:sapphire laser was 5 mW, corresponding to 85 μW absorbed power. We have compared the experimental results with the theoretical prediction, and estimated the value of β to be 10−2.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 1442-1448 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of preparation conditions on the morphology and the resulting oxidation behavior of amorphous GdTbFe films was studied. The morphology was characterized by transmission electron microscopy and mass-density measurements, the magnetic properties by torque and vibrating sample magnetometer measurements, and the oxidation kinetics by in situ measurements of electrical conductivity and Hall hysteresis loops. For the first time a quantitative comparison of the aging kinetics of evaporated and magnetron sputtered films prepared at different Ar sputter gas pressures and substrate-target distances is reported. With increasing the pressure-distance product from 36 to 192 Pa mm the always-observed columnar structure becomes much more pronounced and the mass density, electrical conductivity, and corrosion resistance of the films decrease significantly. The pressure-distance product for thermalization plays an important role in determining the microstructure of the films. Evaporated films show similar features to dc magnetron sputtered films prepared at pressure-distance products of about 100 Pa mm. The oxidation rate is proportional to the porosity of the films and shows, independent of the preparation conditions, an activation energy of 0.3 eV.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 374 (1989), S. 340-348 
    ISSN: 1435-2451
    Keywords: Femur fracture ; Internal fixation ; Posttraumatic osteitis ; Non-union
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Zwischen 1976 and 1986 wurden in unserer Klinik 273 Patienten im Alter von 3 bis 93 Jahren wegen einer Femurschaftfraktur operiert, 79% hatten ein Polytrauma, 254 Patienten mit 269 Osteosynthesen überlebten. 52 von ihnen hatten offene Frakturen. Alle Frakturen wurden unterteilt nach Frakturlokalisation, Frakturtyp und Operationszeitpunkt. Wir sahen 36 Komplikationen (13,4%), d. h. 13 Knocheninfektionen (4,8%) und 23 Pseudarthrosen (8,6%). 40% der Patienten wurden sofort operiert, 23,4% in der ersten Woche, die anderen später. Bei den geschlossenen Brüchen zeigte die sofortige Operation 11,5% Komplikationen, Operation in der ersten Woche 14% und danach nur 5,7% Komplikationen. Wir sahen 7 Infektionen (3,5%) und 20 Pseudarthrosen (9,9%) nach 202 Plattenosteosynthesen und 2 Infektionen (4,3%) und eine Pseudarthrose (2,2%) nach 46 Marknagelungen. Trümmerbrüche hatten eine höhere Komplikationsrate (15%) als andere. Die 23 Brüche am Übergang vom mittleren zum distalen Drittel hatten prozentual die meisten Komplikationen (13% Infektionen und 21% Pseudarthrosen) gefolgt von den 115 Brüchen des mittleren Drittels mit 4,3% Infektionen und 9,6% Pseudarthrosen. Plattenosteosynthesen von Trümmerbrüchen am Übergang vom mittleren zum distalen Drittel hatten die höchste Komplikationsrate überhaupt (4 von 16). Die Gründe für die unterschiedlichen Komplikationsraten werden diskutiert. Die Zunahme der Pseudarthroseanfälligkeit von proximal nach distal wird durch die unterschiedliche Durchblutungswertigkeit der Femurschaftabschnitte erklärt, die wir in früheren Experimenten gefunden haben.
    Notes: Summary Between 1976 and 1986 in our clinic 273 patients aged 3 to 93 years underwent operation of the femur shaft because of fracture. 79% had multiple injuries. 254 with 269 fractures survived. 52 out of them had open fractures. All operated fractures were analysed concerning fracture type, fracture localization and timing of operation. We saw 36 complications (13.4%), 13 bone infections (4.8) and 23 non-unions (8,6%). 40% of the patients were operated immediately, 23.4% within the first week. Early operation of closed fracture showed 11.5% complications, operation within the first week showed 14% complications, and delayed operation only 5.7% complications. We saw 7 infections (3.5%) and 20 non-unions (9.9%) after 202 fixations with AO-plates, and 2 infections (4.3%) and one non-union (2.2%) after 46 Küntscher-nailings. Multi-fragment fractures showed considerably more complications (15%) than other types. 23 fractures in the transition from the middle to the distal third had the highest complication rate (13 infections and 21% non-unions) followed by 115 fractures in middle part with 4.3% infections and 9.6% non-unions. Fixation of multiple-fragment fractures in the transition from the middle to the distal third with AO-plates had the worst rate of non-unions of all (4 out of 16). The reasons for the different complication rates are discussed. The striking increase of complications from proximal to distal shaft regions is explained by different blood flow alterations in femur diaphysis found in former experiments.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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