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| 2. |
- Bender, P., et al.
(författare)
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Structural and magnetic properties of multi-core nanoparticles analysed using a generalised numerical inversion method
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The structural and magnetic properties of magnetic multi-core particles were determined by numerical inversion of small angle scattering and isothermal magnetisation data. The investigated particles consist of iron oxide nanoparticle cores (9 nm) embedded in poly(styrene) spheres (160 nm). A thorough physical characterisation of the particles included transmission electron microscopy, X-ray diffraction and asymmetrical flow field-flow fractionation. Their structure was ultimately disclosed by an indirect Fourier transform of static light scattering, small angle X-ray scattering and small angle neutron scattering data of the colloidal dispersion. The extracted pair distance distribution functions clearly indicated that the cores were mostly accumulated in the outer surface layers of the poly(styrene) spheres. To investigate the magnetic properties, the isothermal magnetisation curves of the multicore particles (immobilised and dispersed in water) were analysed. The study stands out by applying the same numerical approach to extract the apparent moment distributions of the particles as for the indirect Fourier transform. It could be shown that the main peak of the apparent moment distributions correlated to the expected intrinsic moment distribution of the cores. Additional peaks were observed which signaled deviations of the isothermal magnetisation behavior from the non-interacting case, indicating weak dipolar interactions.
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| 3. |
- Hanson, Maj, 1939, et al.
(författare)
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Magnetic properties of epitaxial Ni(001) films and sub-micron particles
- 2001
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 236, s. 139-50
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic properties of Ni particles with well-defined geometry, prepared by electron lithography from epitaxial Ni(001) films of thickness 50 and 60 nm were studied. The particles were circles with diameters 0.6 m and rectangles with sides 0.9 m and 0.3 m, that were positioned in square and rectangular lattices, having lattice constants about twice the particle dimensions. Reference samples and particles with the lattices oriented along the [100] and [110] directions were prepared. Hysteresis curves were obtained for particles and reference samples, in the field range 2T at temperatures between 50 and 300 K. The particles were further imaged by magnetic force microscopy. The coercivities of the particles are about the same as that of the reference samples, being of the order of 10 mT at room temperature and increasing with decreasing temperature. This may be explained by the temperature dependence of the magnetic anisotropy of the Ni film, estimated to K1=-12.5, -12.8 and -87.6 kJ m-3 at 295, 250 and 50 K, respectively. Whereas the hysteresis curves of the particles are governed by the intrinsic properties of the starting film in low fields, the decreased lateral size influences the behaviour in higher fields as demagnetization effects and features characteristic for annihilation and nucleation of domain walls. One of the samples, rectangles with the long axis alone the [110] direction, has a significantly higher remanence and coercivity than the others. The magnetic images show that the demagnetized state of this sample comprises both single-domain and multidomain particles. Corresponding images showed only multidomain particles in all other samples. Thus it was concluded that the actual size (0.9 m0.3 m50 nm) is close to the critical size for single domains in Ni
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| 4. |
- Hanson, Maj, 1939, et al.
(författare)
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Magnetic properties of two-dimensional arrays of epitaxial Fe (001) submicron particles
- 1999
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 85:5, s. 2793-2799
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic properties of two-dimensional arrays of Fe particles with well-defined geometry, prepared by electron lithography from epitaxial Fe (001) films of thickness of 50 nm, have been studied. Circular particles with diameters of 0.6 and 0.4 m and rectangular particles 0.9 m0.3 m and 0.7 m0.2 m, were positioned in square and rectangular lattices, respectively, with lattice constants about twice the particle dimensions. Samples were prepared with the lattices oriented along the 100 and 110 directions. Hysteresis curves were obtained in the field range 2 T at temperatures between 30 and 300 K. The hysteresis curves are characteristic for single particles with a multidomain zero-field state. The magnetization and demagnetization processes are mainly governed by the geometrical shape of the particles and their orientation with respect to the crystal directions and the applied field. This implies that the high quality in the epitaxial Fe films is preserved during the patterning process. Magnetic images, obtained by magnetic force microscopy, support the conclusions drawn from the magnetization measurements. The circular particles showed a fourfold symmetry in their magnetic image, which is compatible with the expected domain structure in a disk with cubic crystalline anisotropy
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| 5. |
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| 6. |
- Hasserius, Ralph, et al.
(författare)
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Vertebral deformation in urban Swedish men and women: prevalence based on 797 subjects
- 2001
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 72:3, s. 273-278
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Tidskriftsartikel (refereegranskat)abstract
- Vertebral fracture-deformation, a common feature of osteoporosis, shows considerable age, sex and geographical variation. We present the prevalence in an urban population of south-west Sweden. Lateral spine radiographs of 797 men and women, age 50-86 years, were evaluated by morphomety. The age-standardized prevalence of subjects with vertebral deformation using the deformation criterion -3 SD was 39 (95%CI 34-43)% in women and 33 (95%CI 28-38)% in men. The prevalence increased with age in both sexes. After adjustment for age, women had a higher prevalence than men, odds ratio 1.4. The proportion of vertebrae with deformation ranged from 2%-11%, increasing with age. The vertebrae most commonly deformed were Th 11, Th 12 and L1.
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| 7. |
- Johansson, Christer, et al.
(författare)
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Impacts of air pollution and health by changing commuting from car to bicycle
- 2017
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 584-585, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- Our study is based on individual data on people’s home and work addresses, as well as their age, sex and physical capacity, in order to establish realistic bicycle-travel distances. A transport model is used to single out data on commuting preferences in the County Stockholm. Our analysis shows there is a very large potential for reducing emissions and exposure if all car drivers living within a distance corresponding to a maximum of a 30 minute bicycle ride to work would change to commuting by bicycle. It would result in more than 111 000 new cyclists, corresponding to an increase of 209% compared to the current situation.Mean population exposure would be reduced by about 7% for both NOx and black carbon (BC) in the most densely populated area of the inner city of Stockholm. Applying a relative risk for NOx of 8% decrease in all-cause mortality associated with a 10 µg m-3 decrease in NOx, this corresponds to more than 449 (95% CI: 340 - 558) years of life saved annually for the Stockholm county area with 2.1 million inhabitants. This is more than double the effect of the reduced mortality estimated for the introduction of congestion charge in Stockholm in 2006. Using NO2 or BC as indicator of health impacts, we obtain 395 (95% CI: 172 - 617) and 185 (95% CI: 158 - 209) years of life saved for the population, respectively. The calculated exposure of BC and its corresponding impacts on mortality are likely underestimated. With this in mind the estimates using NOx, NO2 and BC show quite similar health impacts considering the 95% confidence intervals.
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| 8. |
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| 9. |
- Jonasson, Christian, et al.
(författare)
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Modelling the effect of different core sizes and magnetic interactions inside magnetic nanoparticles on hyperthermia performance
- 2019
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 477, s. 198-202
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental intrinsic loss power (ILP) values, measured at an excitation frequency of 1 MHz and at relatively low field amplitudes of 3.4–9.9 kA/m, as a function of the mean core diameter, for selected magnetic nanoparticles (MNPs). The mean core sizes ranged from ca. 8 nm to 31 nm. Transmission electron microscopy indicated that those with smaller core sizes (less than ca. 22 nm) were single-core MNPs, while those with larger core sizes (ca. 29 nm to 31 nm) were multi-core MNPs. The ILP data showed a peak at core sizes of ca. 20 nm. We show here that this behaviour correlates well with the predicted ILP values obtained using either a non-interacting Debye model, or via dynamic Monte-Carlo simulations, the latter including core-core magnetic interactions for the multi-core particles. This alignment of the models is a consequence of the low field amplitudes used. We also present interesting results showing that the core-core interactions affect the ILP value differently depending on the mean core size.
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| 10. |
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