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Coupling of Ni and NiFe films through an intervening nonmagnetic film (1990)

Layadi, A. ; Artman, J. O. ; Hoffman, R. A. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 67 (1990), S. 4451-4453

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: The magnetic coupling of 20-nm-thick Ni and Ni78Fe22 films through intervening Ag film has been investigated by ferromagnetic resonance (FMR) at 33 GHz. Films were deposited by e-beam evaporation on glass in the order glass/Ag/Ni/Ag/NiFe/Ag. The Ag over- and underlays were 20 nm thick; the central Ag-film thickness was varied between 0 and 20 nm. The coupling of the two ferromagnetic films, A and B, through the interface is modeled by adding −KMA⋅MB to the free energy per unit area. The FMR-mode positions are found from the solutions of a quadratic in K. Subsequently, FMR-mode intensities and linewidths are computed. Input data for these calculations were obtained from observations made on uncoupled Ni and NiFe films. From in-plane dc-field date a variation of K was deduced with a coupling film thickness t of the form exp(−t/τ) with τ equal to 2.68 nm. Limited FMR data taken with the dc field normal to the specimen are consistent with a weak coupling, K∼t−0.83. Little coupling was found in a glass/SiO2/Ni/SiO2/NiFe/SiO2 sequence with the SiO2 films spanning the same thickness range as the Ag in the first sequence. It is believed that the coupling in Ni/Ag/NiFe is dominated by conduction-electron-spin polarization. Some of the coupling may be magnetostatic in origin.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.344901

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Enhanced cytolytic activity of intestinal intraepithelial lymphocytes in patients with Crohn’s disease (2000)

Nüssler, N. C. ; Stange, B. ; Hoffman, R. A. ; [et al.]

Springer

Langenbeck's archives of surgery 385 (2000), S. 218-224

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ISSN: 1435-2451

Keywords: Key words Crohn’s disease ; Cytolytic activity ; Inflammatory bowel disease ; Intraepithelial lymphocytes ; Natural killer cells ; T cells

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract Background and aims: Dysfunction of the immune system with inappropriate responses of lymphocytes to various antigens has been implicated in the development of Crohn’s disease. Therefore, the functional and phenotypic characteristics of intestinal intraepithelial lymphocytes (IEL) in comparison to peripheral blood lymphocytes (PBL) were analyzed in patients with and without Crohn’s disease. Patients and methods: Six patients with Crohn’s disease and six control patients were studied. Isolated IEL and PBL were tested for cytolytic activity against the human adenocarcinoma cells DLD-1 and the human leukemia cells K562 in a 51Cr-release assay. Two-color flow cytometry was performed for phenotype analysis of isolated lymphocytes. Results: IEL from patients with Crohn’s disease showed significantly increased cytolytic activity against epithelial-derived target cells when compared with IEL from control patients. In contrast, no functional changes were detectable among PBL from patients with Crohn’s disease. IEL from patients with Crohn’s disease contained a significantly higher percentage of CD8+ lymphocytes when compared with IEL from control patients, whereas no phenotypic changes were observed among PBL. Conclusions: In Crohn’s disease, the functional and phenotypic changes of T cells are limited to lymphocytes of the intestinal mucosa. Furthermore, it is conceivable that the increased cytolytic activity of IEL contributes to the tissue damage in this disease.