Bibliothek

Notizen: FeNiN films with 0–56 at % Ni concentrations were prepared by dual ion beam sputtering in a nitrogen–argon gas mixture. Effects of nitrogen and nickel concentrations on the structure and magnetic properties of FeNiN films have been studied. FeNiN films with lower nickel and nitrogen concentrations contained the bcc α-(FeNi) phase, films with 8–12 at % nitrogen and 5–25 at % Ni concentrations contained α″-(Fe, Ni)16N2 and γ′-(Fe, Ni)4N phases, and films with 30–56 at % Ni concentrations consisted of a mixture of fcc γ-FeNi alloy and γ′-(Fe, Ni)4N phases. The FeNiN films with 8–12 at % nitrogen and 5–15 at % nickel concentrations showed high saturation magnetization of 2.2–2.3 T and low coercivity of 96–110 A/m. The variation of the magnetic properties was attributed to the change in the structure of the films. © 2002 American Institute of Physics.

Notizen: The crystal structure and magnetic ordering of the Mn spins in polycrystalline NdMnO3 have been investigated by means of neutron diffraction and ac magnetic susceptibility measurements. The compound crystallizes into an orthorhombic symmetry of space group Pbnm. Three peaks were observed in the temperature dependence of the in-phase component of the ac susceptibility, χ′(T). Neutron diffraction measurements show that all three peaks observed in χ′(T) are of magnetic origin, and are associated with the ordering and the reorientation of the Mn spins. Both ferromagnetic and antiferromagnetic couplings between the Mn spins were observed, resulting in a noncollinear magnetic structure. The Mn spins order at Tm(approximate)75 K, and the moment saturates at ∼20 K at 〈μz〉=2.21 μB. © 2000 American Institute of Physics.

Notizen: Haplotype associations of the major histocompatibility complex (MHC) with psoriasis vulgaris (PV) have been demonstrated in different racial or ethnic populations. The objective of this study was to demonstrate the different haplotype associations of the MHC in Chinese patients with psoriasis according to the type of onset and their sex. One hundred and thirty-eight patients with PV and 149 normal control subjects without psoriasis were typed for HLA-A, -B, -C, -DQA1, -DQB1 and -DRB1 by using the PCR with sequence-specific primers. The results showed: (i) HLA-A*26 (26.1% vs. 12.1%, Pc 〈 1 × 10−5), -B*27 (17.03% vs. 1.01%, Pc 〈 1 × 10−7), -Cw*0602 (15.58% vs. 5.03%, Pc 〈 1 × 10−2), -DQA1*0104 (19.93% vs. 9.40%, Pc 〈 1 × 10−3), -DQA1*0201 (22.40% vs. 10.74%, Pc 〈 1 × 10−3), -DQB1*0303 (18.12% vs. 9.73%, Pc 〈 1 × 10−7), and -DRB1*0701/02 (26.09% vs. 9.73%, Pc 〈 1 × 10−7) were significantly increased in PV patients, while HLA-B*57, -DQB1*0201 were slightly increased in PV patients. HLA-Cw*0304 (5.07% vs. 14.43%, Pc 〈 1 × 10−3), -DQA1*0501 (5.79% vs. 14.09%, Pc 〈 0.05) were found to be negatively associated with PV, but HLA-A*2 (2.54% vs. 6.38%, Pc 〈 0.5) was decreased in PV patients without statistical significance. (ii) HLA-A*26-B*27 [P 〈 0.0001, odds ratio (OR) = 48.38], -A*26-Cw*0602 (P 〈 0.0001, OR = 11.84), -B*27-Cw*0602 (P 〈 0.0001, OR = undefined), -DRB1*0701/02-B*27 (P 〈 0.0001, OR = 22.62), -DRB1*0701/02-DQA1*0104 (P 〈 0.0002, OR = 3.59), -DRB1*0701/02-DQB1*0303 (P 〈 0.0001, OR = 5.63), -DQA1*0201-DQB1*0303 (P 〈 0.0002, OR = 7.77), -A*26-B*27-Cw*0602 (P 〈 0.0004, OR = undefined), -A*26-DRB1*0701/02-DQA1*0201-DQB1*0303 (P 〈 0.01, OR = undefined) were identified as risk haplotypes for patients with PV in China. (iii) HLA-A*26 -B*27 (P 〈 0.0001, OR = 58.47), -DQA1*0201-DQB1*0303 (P 〈 0.0001, OR = 8.62), -DRB1*0701/02 -DQA1*0104 (P 〈 0.0002, OR = 4.13), -DRB1*0701/02-DQB1*0303 (P 〈 0.0001, OR = 6.68) and -A*26-DRB1*0701-DQA1*0201 -DQB1*0303 (P 〈 0.006, OR = undefined) were only significantly associated with type I psoriasis compared with controls, while others showed no differences in either type I or type II psoriasis. (iv) These associated haplotypes with PV were not different by sex, except that the frequency of DRB1*0701/02-DQB1*0303 (P 〈 0.0001, OR = 10.14) was higher in male patients with psoriasis. To summarize, this study demonstrated a differential association of HLA and identified some special risk haplotypes in Chinese patients with PV compared with other ethnic or racial populations.

Notizen: Very few articles have aimed to illuminate the clinical profiles of vitiligo in China. We conducted this retrospective survey involving 4118 outpatients with vitiligo in order to identify the differences among various clinical types of vitiligo and their associated disorders. Completed questionnaires (3742) were validated and analysed. Of this large cohort, 1565 (41.8%) individuals presented vitiligo vulgaris, followed by focal, segmental, acrofacial, and universal, in that order. The mean age of vitiligo onset was 18.88 years. More than 60% of the patients were affected before 20 years of age. Patients with segmental vitiligo were affected earlier than those with other types of vitiligo (15.55 years; (P 〈 0.001). More than 74% of the patients presented with focal vitiligo at onset. After 3–5 years, 99% of active vitiligo was worse and shifted from one clinical type to another. However, there was no transformation between acrofacial vitiligo and segmental vitiligo. Compared with the general population, the patients with vitiligo were more likely to be affected by rheumatoid arthritis (P 〈 0.01), ichthyosis (P 〈 0.01), chronic urticaria (P 〈 0.01), or alopecia areata (P 〈 0.01).

Notizen: The microstructural and magnetic properties of amorphous Co/Ti multilayer films and their variation with temperature are investigated by transmission electron microscopy (TEM) analysis and thermomagnetic measurements. Thermomagnetic curves showed two peaks at about 400 and 520 °C. The evolution of the structure monitored in the hot stage of the TEM was found to be consistent with the magnetic changes. The first peak of the saturation magnetization Ms at 400 °C was associated with the transformation from amorphous ferromagnetism to paramagnetism due to the amorphous Co existing in the film. Ms began to increase corresponding to the crystallization point of the ferromagnetic Co phase, which decreased with increasing amounts of Co in the film. Ms reached its maximum at 520 °C and then decreased because the phase transition occurred at a temperature greater than 520 °C and approached completion at 650 °C. The amorphous phase and crystalline phase formation and phase transition during annealing were observed in Co/Ti multilayer thin films and successfully explained the thermomagnetic properties of the film. © 1997 American Institute of Physics.

Notizen: Soft magnetic properties and thermal stability of Fe–Ti–N alloys films have been investigated. Thin films with composition in the range of 8–10 at. % Ti, 10.5–14 at. % N, and balance Fe were prepared by reactive sputtering method. The films exhibit good soft magnetic properties in the as-deposited condition without any post heat treatment, e.g., low coercivity Hc∼1.5 Oe, high permeability μ∼3200 at 1 MHz and very high saturation magnetization 4πMs∼24 kG. The thermal stability of these films was also found to be good, e.g., Hc was less than 2 Oe, and 4πMs was higher than 23 kG for the films annealed up to 500 °C. The high electrical resistivity ρ∼100 μ Ω cm of the films can minimize the eddy current loss in the high frequency applications. The combination of high 4πMs and relatively high anisotropy field Ha∼10 Oe in the film is conductive to the suppression of the undesirable ferromagnetic resonance interfere up to the GHz frequency range. © 1999 American Institute of Physics.

Notizen: We present an efficient variant of the fast-multipole method for calculating long-range interactions in three-dimensional Coulombic systems. Using a multipole expansion based on the solid harmonics instead of the more common spherical harmonics leads to a greater increase in computational efficiency than a recently-reported fast-Fourier transform method, with none of the overhead associated with that approach. © 1996 American Institute of Physics.