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  • Electronic Resource  (8)
  • 1985-1989  (5)
  • 1980-1984  (3)
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  • Electronic Resource  (8)
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  • 1
    Electronic Resource
    Electronic Resource
    Magnetization processes in ferromagnetic cubes (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1347-1357 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A cubic discretization procedure of the micromagnetic energy functional is used to carry out numerical studies of the magnetization process in ferromagnetic cubes. Equilibrium magnetization configurations and their switching behavior are calculated for particle sizes in the range from 100 to 550 A(ring). In the model calculations the particles are assumed to have uniaxial crystalline anisotropy with an anisotropy constant of 18 500 erg/cm3, a saturation magnetization of 370 emu/cm3, and an exchange constant of 10−6 erg/cm. For particle sizes smaller than 520 A(ring) the remanent state has a flowerlike magnetization configuration. Beyond 520 A(ring) this state is replaced by a vortex structure about the easy axis. For particles smaller than 450 A(ring) switching occurs by approximately uniform rotation of the flower state. The switching fields are larger than the corresponding Stoner–Wohlfarth value. Beyond 450 A(ring) the application of an external field leads to the formation of a vortex configuration. The switching of the vortex configuration involves rotation of the vortex axis at a reduced value of the switching field. The angular dependence of the coercive field is calculated for particle sizes of 200, 400, and 550 A(ring).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341858
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ferromagnetic switching in elongated γ-Fe2O3 particles (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5832-5834 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results of numerical micromagnetic calculations of the switching process in elongated γ-Fe2O3 particles are reported. The particles are represented by square rectangular prisms of aspect ratio 3:1 and 5:1, respectively. The crystalline anisotropy is cubic with K1=−4.6×104 erg/cm3 and with the [110] direction in the long particle axis. The application of a reverse field leads to formation of vortices at the ends of the particle. As the reverse field is increased in magnitude the vortices expand from the ends of the particle inwards. Equilibrium and transient magnetization states are computed as a function of particle size. The resulting dependence of the switching field on the particle size and on the angle of the applied field is similar to what has been suggested by experimental evidence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342222
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Micromagnetic studies of thin metallic films (invited) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3248-3253 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A computer simulation model has been developed to conduct micromagnetic studies of thin magnetic films. Thin-film media are modeled as a planar hexagonal array of hexagonally shaped grains. Each grain is a single domain particle whose magnetization reverses by coherent rotation. The computation utilizes coupled gyromagnetic dynamic equations with phenomenological Landau–Lifshitz damping. In particular, the effects of particle interactions are investigated. The effect of media microstructure on magnetic hysteresis is examined as well as the effect of intergranular exchange coupling. The difference between planar and completely random orientation of the crystalline anisotropy axes is discussed. Recorded transitions are simulated by allowing a pair of perfect transitions to relax. With no intergranular exchange coupling, the transitions show profound irregularity and zig-zag structure. Intergranular exchange coupling produces more uniform transitions with increased zig-zag structure amplitude. For a closely spaced transition pair, the equilibrium configuration yields percolated transition boundaries with stable reverse island domains. The effect of gyromagnetic precession also has been examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341167
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Magnetization reversal in CoCr perpendicular thin films (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1291-1307 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Computer simulation has been utilized to study magnetization reversal processes in CoCr perpendicular films. The model is based on the columnar structure of the film. Each column is considered to be a single crystal with perpendicular uniaxial crystalline anisotropy. The model assumes that each column is always uniformly magnetized even during its magnetization reversal. The gyromagnetic equation of motion with phenomenological Landau–Lifshitz damping is utilized to describe the magnetization rotation of this coupled system. The study focuses on the collective magnetization reversal modes of the particles due to magnetostatic interactions and intergranular exchange coupling. Low nucleation fields occur which are characterized by a planar chain nucleation mode. This yields coercivities equal to or less than the crystalline anisotropy field 2K/M. It is argued that, due to this collective process, the uniform rotation reversal mechanism for the individual particles in the film is energetically more favorable than nonuniform reversal, such as curling. Intercolumn exchange coupling significantly reduces the coercivity and an increase of the exchange coupling strength changes the magnetization behavior from "particulate'' to "continuous.''
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344428
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  • 5
    Electronic Resource
    Electronic Resource
    Plasma zinc and magnesium alterations in acute myocardial infarction (1980)
    Springer
    Journal of molecular medicine 58 (1980), S. 1143-1146 
    Details
    ISSN: 1432-1440
    Keywords: Herzinfarkt ; Zink ; Magnesium ; Myocardial infarction ; Zinc ; Magnesium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary In 31 patients suffering from acute myocardial infarction plasma zinc and magnesium concentrations were measured. In acute infarction plasma zinc concentrations were strikingly decreased and plasma magnesium concentrations slightly decreased. A close correlation between fall in zinc concentrations and the rise of serum CPK in these patients could be observed. No correlations were found between infarct localisation and sex and alterations in zinc concentrations. In contrast, a close correlation between fall in zinc content and severity of infarction occurred. Thus, the observed alterations in plasma zinc probably can be used as a diagnostic and prognostic indicator. Furthermore it should be considered whether zinc substitution would be of therapeutical benefit in patients suffering from acute myocardial infarction.
    Notes: Zusammenfassung Bei 31 Patienten mit akutem Herzinfarkt wurden über einen Zeitraum von 14 Tagen die Zink- und Magnesiumkonzentrationen im Plasma bestimmt. In der akuten Phase des Infarktes (Maximum am 2. Tage) zeigte sich ein hoch signifikanter Abfall der Plasma-Zinkkonzentration. Die Magnesiumkonzentrationen waren dagegen nur gering vermindert. Nach etwa 7 Tagen normalisierten sich die Zinkkonzentrationen im Plasma. Es ließ sich eine enge Korrelation zwischen Abfall des Zinkspiegels und Anstieg der Serum-Creatinin-Phosphorkinase aufzeigen. Keine Korrelationen bestanden dagegen zwischen Infarktlokalisation, Geschlechtsverteilung und Änderungen in der Plasma-Zinkkonzentration. Auffällig war dagegen die deutlich positive Korrelation zwischen Schwere des Infarktes und Abfall der Zinkkonzentration. Auf Grund unserer Untersuchungen kann der Bestimmung der Plasma-Zinkkonzentration beim akuten Herzinfarkt sowohl diagnostischeals auch prognostische Bedeutungzukommen. Ferner ist zu diskutieren, inwieweit eine vorübergehende Zink-Verabreichung beim akuten Herzinfarkt sinnvoll ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01477236
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  • 6
    Electronic Resource
    Electronic Resource
    Zinc concentrations in plasma and erythrocytes in digitalized patients (1981)
    Springer
    Journal of molecular medicine 59 (1981), S. 1345-1347 
    Details
    ISSN: 1432-1440
    Keywords: Digitalistherapy ; Zinc ; Transmembrane transport ; Digitalistherapie ; Zink ; Transmembraner Transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 31 gesunden Kontrollpersonen sowie 63 Patienten mit Digitalistherapie wurden die Zink-, Natrium-, Kalium- und Magnesiumkonzentrationen im Plasma und in den Erythrozyten bestimmt. In den Erythrozyten der mit Digitalis behandelten Patienten zeigte sich neben der von unserer Arbeitsgruppe bereits beschriebenen Zunahme der Natriumkonzentration ein deutlicher Anstieg des Zinkgehaltes. Die intraerythrozytären Kalium- und Magnesiumkonzentrationen sowie die analysierten Plasmaparameter wiesen keine Abweichungen von der Norm auf. Es wird diskutiert, daß die erhöhte Zinkkonzentration möglicherweise ebenfalls auf einer Digitalis bedingten Störung des transmembranen Ionentransportes beruht.
    Notes: Summary Determinations of zinc, sodium, potassium and magnesium in plasma and red blood cells were performed in 31 controls and 63 patients treated with digitalis. In digitalized patients sodium and zinc concentrations in red blood cells were significantly increased. The intraerythrocyte magnesium and potassium levels as well as all investigated electrolytes in plasma remained within the normal range. There was a close relationship between the increase of sodium and zinc content in red blood cells, indicating alterations in transmembrane transport mechanisms induced by digitalis therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01720554
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  • 7
    Electronic Resource
    Electronic Resource
    Action of gamma endonuclease on clustered lesions in irradiated DNA (1988)
    Springer
    Radiation and environmental biophysics 27 (1988), S. 123-132 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary Irradiation of DNA in situ i.e. in phage particles or in the cell leads to alterations of single DNA nucleotides as well as to clustered lesions such as double strand breaks or unpaired DNA regions the latter being sensitive to digestion by S 1 nuclease. A contribution will be made to the configuration of such S 1-nuclease-sensitive sites (S 1 sites). DNA from irradiated lambda phage containing S 1 sites was treated with gamma endonuclease fromM. luteus which is known to split the nucleotide strand at the position of oxidized pyrimidine base. It was found that the gamma endonuclease induces double-strand breaks at some of the S 1 sites indicating double base damage within this site. However, half of the S 1 sites are not converted into a double-strand break by the gamma endonuclease, indicating base damage only on one strand within the unpaired region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01214602
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Multielementanalyse mit ET-AAS im Rahmen der Human-Umweltprobenbank Münster (1984)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 317 (1984), S. 462-467 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Bestimmung von Spurenelementen im Rahmen der Human-Umweltprobenbank Münster erfolgt bevorzugt durch elektrothermale AAS. Jede Matrix erfordert ein spezifisches Analysenprogramm. Zum Beispiel können im Salpetersäureaufschluß von Haaren bis zu 12 Spurenmetalle halbautomatisch bestimmt werden. Nicht nur toxische Spurenmetalle werden bestimmt, sondern auch andere Substanzen, die im biologischen System mit diesen interferieren können.
    Notes: Summary The determination of traces of metals in these samples is preferably be carried out by electrothermal AAS. Each matrix requires a specific analytical program. For example, up to 12 trace elements can be determined semiautomatically in hairs after nitric acid digestion. Not only toxic trace metals are examined, but also other traces which may interfere with these in the biological system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00494517
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