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  • Articles: DFG German National Licenses  (104)
  • 1995-1999  (102)
  • 1950-1954  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Carcinogenesis in accessory sex organs of rats induced by 3,2′-dimethyl-4-aminobiphenyl: response to androgen deprivation (1997)
    Springer
    Histochemistry and cell biology 108 (1997), S. 505-512 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  It is generally accepted that early human prostate cancers reveal higher androgen dependency than do advanced ones. In the present study, we examined whether the animal model of prostate cancer has already lost androgen dependency at the early stages of carcinogenesis. At experimental week 46, androgen deprivation was induced in rats and the incidences of atypical hyperplasia and cancer were examined in the ventral, dorsolateral prostate, coagulating glands, and seminal vesicles. Androgen deprivation significantly lowered the incidence of atypical hyperplasia in all four organs. As for the incidence of cancer, no significant differences were observed in the coagulating glands and seminal vesicles. Regarding atypical hyperplasia, androgen deprivation significantly decreased the proliferative cell nuclear antigen labeling index in the coagulating gland and seminal vesicles. The presence of cancer was also decreased in the coagulating gland but not in the seminal vesicles. With control group specimens, more intense staining of androgen receptor was observed in atypical hyperplasias than in cancers. Compared with the atypical hyperplasias, the cancers revealed low androgen dependency at the early stages of carcinogenesis. The cancers in the seminal vesicles also revealed higher androgen independency than did those in the coagulating gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050191
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  • 2
    Electronic Resource
    Electronic Resource
    Time-temperature-transformation study of a nanocrystalline Fe91Zr7B2 soft magnetic alloy : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5149-5151 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure, soft magnetic properties, magnetostriction, grain size and volume fraction of the residual amorphous phase have been studied for an amorphous Fe91Zr7B2 alloy annealed for periods of 60 s–1080 ks, at temperatures of 823–973 K. The highest permeability (at 1 kHz and 0.4 A/m) 31,000 and smallest coercivity 4.2 A/m are obtained for the sample annealed at 923 K for 60 s, where a small grain size (≈12 nm) and about 35% of the residual amorphous phase are measured. The coercivity of the nanocrystalline alloy varies as the 3rd power of the grain size, corresponding to the case where the magnetically coupled region has a dimensionality between two and three. This slightly low dimensionality is presumed to be due to the alignment of the magnetization in the sample plane. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361536
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  • 3
    Electronic Resource
    Electronic Resource
    Structural anisotropy of Tb/Fe multilayers : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6270-6272 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the local structural anisotropy of Tb/Fe multilayers using linear polarized synchrotron radiation. X-ray absorption measurements were performed at Fe K edge (7.1 keV) using normal and glancing angle incident photon. From the Fe extended x-ray absorption fine structure (EXAFS), the local structural anisotropy was found for all multilayers as a slight difference of oscillation amplitude between the two incident directions. From the Fourier transformed EXAFS spectra, it is found that the local structural anisotropy shows the maximum at bilayer period of about 1 nm, where perpendicular magnetic anisotropy also shows the maximum value in various rare-earth/transition metal multilayers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362033
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of the spontaneous magnetization in the grain boundary region on the magnetic softness of nanocrystalline materials (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 4400-4402 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The relationship between the mean hyperfine field of the residual intergranular amorphous phase 〈Bhf〉 and the coercivity Hc in various nanocrystalline soft magnetic samples has been investigated in order to clarify the effect of the spontaneous magnetization in the grain boundary region on their magnetic softness. Nanocrystalline samples with various 〈Bhf〉 values were prepared by annealing an amorphous Fe91Zr7B2 precursor for periods of 60 s–108 ks, at temperatures of 823–973 K. Hc shows a clear tendency to decrease with increasing 〈Bhf〉 or decreasing volume fraction of the residual amorphous phase. These effects of the residual amorphous phase on Hc are well understood within the framework of our extended two-phase random anisotropy model where both the exchange stiffness constant and volume fraction of the grain boundary phase are relevant to the exchange correlation length. Our results indicate that the exchange stiffness constant of the intergranular region varies as the square of the spontaneous magnetization of the residual amorphous phase. A small exchange stiffness constant on the order of 10−13 J/m is predicted for the residual amorphous phase in the Fe–Zr–B alloy. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369797
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  • 5
    Electronic Resource
    Electronic Resource
    Morphological and magnetic characteristics of monodispersed Co-cluster assemblies (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5726-5732 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Co-cluster-assembled films have been prepared using a size-controllable cluster beam deposition system, by which monodispersed Co clusters with a mean diameter, d=6–13 nm are available. Their morphology and magnetic properties have been studied by scanning electron microscopy (SEM), small-angle x-ray scattering (SAXS) and magnetization measurements. The SEM images show that the film has a porous structure consisting of fine grains without a columnar texture and its density is about 25% of the bulk Co. The SAXS measurements indicate that monodispersivity of the incident clusters is maintained through their assembling process only for d=13 nm. All the specimens exhibit ferromagnetic behavior at room temperature and the magnetic coercive field Hc rapidly increases with decreasing temperature: Hc=168 kA/m (2.1 kOe) at 5 K. Such an enhancement in Hc is ascribed to the exchange anisotropy which arises from the antiferromagnetic Co–oxide layers covering the Co clusters, and to the assemblies of single-domain ferromagnetic clusters with the structure modification and magnetic interaction among them. The monotonic increase in Hc at 300 K with increasing d is simply understood in terms of the single-domain particle theory. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371585
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  • 6
    Electronic Resource
    Electronic Resource
    Structural and optical properties of type II GaSb/GaAs self-assembled quantum dots grown by molecular beam epitaxy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 8349-8352 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report structural and optical properties of GaSb/GaAs self-assembled quantum dots (QDs) grown by molecular beam epitaxy. The QDs, with nanometer-scale dimensions, were characterized by atomic force microscopy. Furthermore, in photoluminescence (PL) measurements the feature from the QDs was observed at ∼1.1 eV, clearly separated from that of the wetting layer at ∼1.3 eV. With increasing excitation power, the peak from the QDs displayed a large shift towards higher energy. In addition, the temperature dependence of PL yielded a large thermal activation energy, 130 meV, confirming the strong localization of excitons in the QDs. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370622
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  • 7
    Electronic Resource
    Electronic Resource
    Formation and decomposition of Fe3B/Nd2Fe14B nanocomposite structure in Fe–Nd–B–Cr melt-spun ribbons under isothermal annealing (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5914-5916 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The decomposition process of the precursor amorphous phase in Nd5Fe77−xB18Crx (x=0 and 3) has been studied by means of x-ray diffractometry and Mössbauer spectroscopy with particular attention paid to the formation of Nd2Fe14B induced by Cr. Amorphous Nd5Fe74Cr3B18 was confirmed to decompose to stable α-Fe/Fe2B/NdFe4B4 via metastable Fe3B/Nd2Fe14B during isothermal annealing at 953 K. However, the metastable formation of magnetically hard Fe3B/Nd2Fe14B in the Cr-added system is spoiled by a preannealing treatment at 873 K which alters the metastable decomposition products from Fe3B/Nd2Fe14B to Fe3B/Nd2Fe23B3. We discuss the Cr-induced formation of Nd2Fe14B from the viewpoint of kinetics. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369912
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  • 8
    Electronic Resource
    Electronic Resource
    Optical spectroscopy of self-assembled type II GaSb/GaAs quantum dot structures grown by molecular beam epitaxy (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2856-2858 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report an optical spectroscopic study of GaSb/GaAs quantum dots (QDs) formed by the Stranski–Krastanow growth mode using molecular beam epitaxy. We identify the QD luminescence by photoluminescence obtained at different excitation energies and densities. We show that, for these structures, not only the spectral position of peaks, but also their relative intensities are critically dependent upon the density of photogenerated carriers. Photoluminescence excitation (PLE) measurements confirm our assignment of the QD related peaks and a feature ∼25–27 meV higher in energy than the PLE detection energy is discussed in terms of phonon relaxation. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121480
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  • 9
    Electronic Resource
    Electronic Resource
    Reduction of threading dislocations by InGaAs interlayer in GaAs layers grown on Si substrates (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2917-2919 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-quality GaAs epilayers with dislocation densities of 1.2×106 cm−2 on (100)Si substrates have been obtained by insertion of an InGaAs strained interlayer combined with thermal cycle annealing instead of strained layer superlattices. All the layers were grown by low-pressure metalorganic vapor phase epitaxy. The threading dislocation density near the surface of 4 μm thick GaAs was measured by plan-view transmission electron microscopy. The threading dislocation density was found to be very sensitive to the In composition of the interlayer and the specifics of thermal cycle annealing. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122629
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  • 10
    Electronic Resource
    Electronic Resource
    Light emission from individual self-assembled InAs/GaAs quantum dots excited by tunneling current injection (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1460-1462 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report emission from individual quantum dots excited by tunneling current injection using a scanning tunneling microscope (STM). By scanning the STM tip above the self-assembled InAs quantum dots, a spatially resolved scanning tunneling luminescence (STL) image was measured, which contained a fluorescent circular region with a diameter of 50 nm originating from a single InAs quantum dot. It was found that the spatial resolution of the STL system was about 40 nm, which is mainly due to lateral diffusion of holes injected into a GaAs capping layer grown at low temperature (480 °C). We also obtained STL spectra with a sharp single luminescent peak from a single InAs quantum dot. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122174
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