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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6956-6958 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth temperature is one of the critical parameters in the formation of the chemically ordered L10 phase in FePt. To uniquely determine the influence of growth temperature, while other growth parameters remain fixed, we present the "temperature wedge method" where a calibrated temperature gradient of several hundred Kelvin is established across the substrate during co-deposition of Fe and Pt. Samples were deposited in a temperature range of 250 °C–600 °C simultaneously on MgO(001) and MgO(110) substrates. The Fe(approximate)50Pt(approximate)50 composition was verified by Rutherford backscattering. The chemical order parameter, S, at different positions along the samples, i.e., at different growth temperatures, was determined by x-ray diffraction measurements, and it was found that at all temperatures S(001)〉S(110). Perpendicular and in-plane magneto-optic Kerr hysteresis loop measurements indicate large magnetic anisotropy at the "hot ends" of the samples, corresponding to large values of S. © 2000 American Institute of Physics.
    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 87 (2000), S. 2989-2993 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of interface reactions between the magnetic layer and the protective carbon coating, and the influence of these interactions on magnetic properties of rigid disk media for magnetic data storage is presented. Quaternary CoPtCrB and CoPtCrTa alloy films and protective hydrogenated or nitrogenated carbon coatings were deposited by dc magnetron sputtering onto metal hard disks (AlMg substrate/electroplated NiP layer/Cr underlayer). Core level x-ray photoelectron spectroscopy of nitrogenated carbon films on B-containing alloys showed the formation of boron nitride and small amounts of chromium nitride at the interface, and also indicated the likely presence of chromium carbide. The amount of boron nitride at the interface varied depending on substrate bias voltage and temperature during deposition of the carbon coating. From a quantitative analysis of the x-ray photoelectron spectra it was inferred that boron nitride formation was controlled by the diffusion of boron from deeper regions of the magnetic layer to the interface. Surprisingly, compared to disks using the same magnetic alloy but with a hydrogenated or pure carbon coating, no effects of these interface reactions on the magnetic properties of the disks could be detected. In contrast, for a Ta-containing alloy the same comparison revealed a drop in the coercivity of up to 200 Oe in disks with nitrogenated carbon overcoats. Strong evidence for the formation of tantalum nitride as well as small amounts of chromium nitride was found in the photoelectron spectra. Thus, while the formation of boron nitride at the interface of CoPtCrB media and protective carbon coating does not affect the magnetic properties of the disks in the range of boron and nitrogen concentrations investigated here, small changes in the chemical environment of Ta and/or Cr can lead to significant changes in the magnetic properties of the CoPtCrTa media. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 5686-5692 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic domain structure and magnetization curves of chemically ordered epitaxial FePt (001) films with perpendicular magnetic anisotropy are discussed. Films were dc magnetron sputtered from a Fe50Pt50 alloy target onto Pt seeded MgO (001) at substrate temperatures of 550 °C. The thickness of the FePt layers was varied between 18 and 170 nm. Specular and grazing incidence x-ray diffraction measurements confirm the presence of the anisotropic, face centered tetragonal (L10) crystal structure. Long range chemical order parameters of up to 0.95 and small mosaic spread, similar to results reported for FePt (001) films grown by molecular beam epitaxy. For film thicknesses ≥50 nm in-plane and out-of-plane hysteresis measurements indicate large perpendicular magnetic anisotropies and at the same time low (about 10%) perpendicular remanence. Magnetic force microscopy reveals highly interconnected perpendicular stripe domain patterns. From their characteristic widths, which are strongly dependent on the film thickness, a value of the dipolar length D0∼50±5 nm is derived. Assuming an exchange constant of 10−6 erg/cm, this value is consistent with an anisotropy constant K1∼1×108 erg/cc. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Histopathology 37 (2000), S. 0 
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: AimsBone marrow histopathology reveals a striking heterogeneity at diagnosis of Philadelphia chromosome positive (Ph1+) chronic myelogenous leukaemia (CML). Based on semiquantitative evaluations of the number of megakaryocytes and the content of fibres, various histological subtypes have been postulated. However, little information exists on whether these groups represent stable categories of the different classification systems and whether therapeutic regimes exert any influence on the putative shift of histological patterns.Methods and resultsA retrospective clinicopathological study was performed on 396 bone marrow biopsies derived from 173 patients. There were at least two representative trephines taken at diagnosis and at median intervals of 16 months. Processing of the specimens involved immunostaining with CD61 (megakaryopoiesis) and Ret40f (erythropoiesis) and Gomori's silver impregnation technique. Based on morphometric analysis and in accordance with the general appearance of bone marrow histology three different histological subtypes were distinguished. These consisted of a granulocytic (51 patients), a predominantly megakaryocytic (73 patients) and a myelofibrotic pattern (49 patients). Follow-up biopsies revealed that a significant transition of histological groups occurred and that, independently of treatment modalities, the myelofibrotic category was associated with an unfavourable prognosis. Of the 124 patients without myelofibrosis at onset, 42% later transformed into the myelofibrotic subtype. However, these patients showed no prevalence of either a pre-existing granulocytic or megakaryocytic growth. Myelofibrotic changes were significantly associated with interferon (IFN) and busulfan (BU) therapy. On the other hand, a transition of a myelofibrotic into a nonfibrotic subtype was detectable in 17 of the 49 patients under study and related to hydroxyurea (HU) treatment.ConclusionsHistological classification systems of bone marrow features in CML do not represent stable patterns, but may be significantly altered by therapy, in particular IFN and HU.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Comparative evaluation of the prognostic value of MUC1, MUC2, sialyl-Lewisa and sialyl-Lewisx antigens in colorectal adenocarcinoma Aims: The significance of MUC1, MUC2 and sialylated Lewis blood group antigens as prognostic markers in colorectal adenocarcinoma was investigated in a large series of patients because previous investigations revealed inconsistent results due to unrelated tumour samples from different patient groups and methodological differences. Methods and results: Tissues from 243 patients with colorectal adenocarcinoma were stained immunohistochemically. MUC1 showed a strong immunoreactivity (in more than 35% of the tumour area) in 32.5%, MUC2 in 51.0%, sialyl-Lewisx in 67.9% and sialyl-Lewisa in 73.7% of the cases, respectively. MUC1 immunoreactivity displayed a significant correlation with tumour progression as reflected by advancing pTNM staging and poor differentiation. MUC2 expression was significantly stronger in mucinous adenocarcinomas. Sialyl-Lewisx immunostaining correlated with the extent of lymph node metastasis as well as low cytological differentiation. According to univariate and multivariate analysis (P 〈 0.0001) only MUC1 reactivity represented a marker of worse survival probability, opposed to the sialylated Lewis antigens that did not exert a predictive value. Conclusions: According to our data, MUC1 and sialyl-Lewisx immunoreactivity exhibit statistically significant correlations with established markers of tumour progression. However, only MUC1 presents as an independent prognostic factor of colorectal adenocarcinoma.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In addition to predominant granulocytic proliferation, bone marrow morphology in Philadelphia chromosome positive (Ph1+) CML is characterized by atypical dwarf or microforms of megakaryocytes. However, following therapy with interferon-α2b (IFN), these micromegakaryocytes occur less frequently. The purpose of this study was to elucidate whether the reappearance of normal megakaryocytes may be associated also with a reduction of the bcr/abl-positive cell clone.〈section xml:id="abs1-2"〉〈title type="main"〉Methods and results:Fluorescence in-situ hybridization (FISH) technique in combination with immunomorphometry (CD61) was performed on trephine biopsies. A total of 311 CD61-positive megakaryocytes, including precursors and atypical microforms, were evaluated in pre-treatment specimens derived from 11 patients with Ph1+ CML. A specific fusion site marking the bcr/abl translocation was found in 87% of megakaryocytes which showed a size of 169 ± 35 μm2. In untreated patients, atypical microforms (size 200 μm2) were observed in 66% of the total megakaryocytic population. Following IFN therapy 369 megakaryocytes could be analysed in sequential examinations and were found to display a significant decrease (63%) in positive fusion signals. In addition there was also a significant enhancement in average size (252 ± 66 μm2) reflecting a reduction in the number of micromegakaryocytes (43%). These findings were particularly conspicuous in three patients with a major to complete cytogenetic remission.〈section xml:id="abs1-3"〉〈title type="main"〉Conclusions:A normalization of megakaryocyte size following IFN therapy in CML is significantly associated with a loss of the bcr/abl translocation site and therefore indicates a (partial) recovery of normal haematopoiesis.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Using a sequential double-imunostaining technique, a morphometric analysis was performed on routinely processed bone marrow trephines from 20 patients with secondary (reactive) polycythaemia and 28 patients with polycythaemia rubra vera to determine the proliferation capacity of erythropoiesis. Monoclonal antibodies PC10—anti-proliferating cell nuclear antigen (PCNA)—and Ret40f—anti-glycophorin C—were employed. For comparison with the PCNA-labelling index, in a pilot study, Ki-67 was additionally used on frozen-section material. In comparison with normal bone marrow (15 patients) morphometric and statistical evaluation revealed a numerical increase in erythroid precursors (pro-, erythro- and normoblasts) in secondary polycythaemia and to a pronounced degree in polycythaemia rubra vera. In comparison with secondary polycythaemia and the control group, in polycythaemia rubra vera there was a significant enhancement of proliferation according to PCNA-staining reactivity in all haematopoietic cell elements and particularly in the erythroid series. Evaluation of PCNA v. Ki-67 immunostaining disclosed only a slight difference, which could be mainly attributed to various modalities of antigen expression during the cell cycle. Our findings are in keeping with in vitro studies on cultured erythroid progenitor cells and, in problematic cases, may present a valuable aid in differentiation between reactive lesions and polycythaemia rubra vera.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Applied Surface Science 65-66 (1993), S. 175-178 
    ISSN: 0169-4332
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 119 (1993), S. 141-149 
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0022-5320
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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