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| 2. |
- Gustavsson, Fredrik, et al.
(författare)
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Magnetic moment and anisotropy at the Fe/ZnSe(001) interface studied by conversion electron Mössbauer spectroscopy
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:2, s. 024405-
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Tidskriftsartikel (refereegranskat)abstract
- The interface magnetic properties of Fe/ZnSe heterostructures grown on GaAs(001) by molecular-beam epitaxy have been investigated using conversion electron Mössbauer spectroscopy (CEMS) and macroscopic magnetic measurements. For Fe films thinner than 100 Å an in-plane 〈110〉 uniaxial magnetic anisotropy was found and the magnetization loops could successfully be described by the simple Stoner-Wohlfarth model, which implies that the magnetization reverses only by coherent rotation and jump processes. For the interface analysis, a 5-Å-thick layer of enriched 57Fe was deposited on the ZnSe surface and buried under 20 Å of natural Fe. In this way the 57Fe serves as a local probe of the interface magnetic environment in a bulklike Fe film since the CEMS technique is only sensitive to this isotope of Fe. An interface magnetic moment of 2.18 μB was found and, in relation to 2.2 μB for bulk bcc Fe, this precludes the presence of any interface reactions. Surprisingly, however, the direction of the interface magnetic moment turned out to be reoriented from the [110] direction by almost 30°, an effect that was assumed to arise from the distribution of unidirectional tetrahedral bonds present on the Zn c(2×2) reconstructed ZnSe surface.
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| 4. |
- Karlsson, J, 1966-, et al.
(författare)
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Sequencing of the Francisella tularensis strain Schu 4 genome reveals the shikimate and purine metabolic pathways, targets for the construction of a rationally attenuated auxotrophic vaccine.
- 2000
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Ingår i: Microbial & Comparative Genomics. - : Mary Ann Liebert Inc. - 1090-6592 .- 2168-6637. ; 5:1, s. 25-39
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Tidskriftsartikel (refereegranskat)abstract
- Francisella tularensis is the etiological agent of tularemia, a serious disease in several Northern hemisphere countries. The organism has fastidious growth requirements and is very poorly understood at the genetic and molecular levels. Given the lack of data on this organism, we undertook the sample sequencing of its genome. A random library of DNA fragments from a highly virulent strain (Schu 4) of F. tularensis was constructed and the nucleotide sequences of 13,904 cloned fragments were determined and assembled into 353 contigs. A total of 1.83 Mb of nucleotide sequence was obtained that had a G+C content of 33.2%. Genes located on plasmids pOM1 and pNFL10, which had been previously isolated from low virulence strains of F. tularensis, were absent but all of the other known F. tularensis genes were represented in the assembled data. F. tularensis Schu4 was able to grow in the absence of aromatic amino acids and orthologues of genes which could encode enzymes in the shikimate pathway in other bacteria were identified in the assembled data. Genes that could encode all of the enzymes in the purine biosynthetic and most of the en- zymes in the purine salvage pathways were also identified. This data will be used to develop defined rationally attenuated mutants of F. tularensis, which could be used as replacements for the existing genetically undefined live vaccine strain.
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| 5. |
- Sjöstedt, Elisabeth, et al.
(författare)
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An alternative way of linearizing the augmented-plane-wave method
- 2000
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Ingår i: Solid State Communications. - 0038-1098 .- 1879-2766. ; 114:1, s. 15-20
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Tidskriftsartikel (refereegranskat)abstract
- A new basis set for a full potential treatment of crystal electronic structures is presented and compared to that of the well-known linearized augmented plane-wave (LAPW) method. The basis set consists of energy-independent augmented plane-wave functions combined with local orbitals. Each basis function is continuous over the whole unit cell but it may have a discontinuous slope at the muffin-tin boundaries, i.e. at the surfaces of atomic centered, non-overlapping spheres. This alternative way to linearize the augmented plane-wave method is shown to reproduce the accurate results of the LAPW method, but using a smaller basis set size. The reduction in number of basis functions is most significant for open structures.
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