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- Elsik, Christine G., et al.
(författare)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 4. |
- Intarasiri, S., et al.
(författare)
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Ion beam synthesis of silicon carbide
- 2005
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Ingår i: PARTICLE BEAMS & PLASMA INTERACTION ON MATERIALS AND ION & PLASMA SURFACE FINISHING 2004. - 3908451124 ; , s. 51-54
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Konferensbidrag (refereegranskat)abstract
- Formation and crystallization of a thin near-surface layer of silicon carbide on a silicon substrate, created by ion-beam synthesis (IBS), are discussed. 80 and 40 keV carbon ions were implanted into a (100) high-purity p-type silicon substrate at roorn temperature and 400 degrees C, respectively, using doses in excess of 10(17) ions/cm(2). Elastic recoil detection analysis (ERDA) technique, developed for routine atomic depth profiling at the Angstrom laboratory, Uppsala University, Sweden, was used to investigate the depth distributions of implanted-ions. Infrared transmittance measurement was used as an indication of SiC in the implanted Si substrate. For the samples implanted at high temperature, the results show the existence of a peak at 797 cm(-1), indicating the presence of beta-SiC, already directly formed during the implantation without post-implantation annealing. While for the samples implanted at room temperature, starting with the band of amorphous Si-C network, the crystalline SiC appears at the annealing temperature as low as 900 degrees C. In both cases, during further annealing in vacuum, the peak grows in height and narrows in width (according to the measured FWHM) with increasing annealing temperature, indicating a further growth of the SiC layer. However, for thermal annealing at 1000 T in a vacuum furnace the SiC crystallization was not completed and crystal imperfection where still present. Complementary to IR, Raman scattering measurements were performed. Although no direct evidence of SiC vibrations were observed, the appearance and disappearance of both Si-Si and C-C related bands points out to the formation of silicon and carbon clusters in the implanted layer.
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| 6. |
- Razpet, A., et al.
(författare)
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Fabrication of high-density ordered nanoarrays in silicon dioxide by MeV ion track lithography
- 2005
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 97:4
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembled nanoporous alumina films were employed as masks for MeV ion track lithography. Films with thickness of 2 mum and pore diameters of 30 and 70 nm were attached to thermally grown SiO2 covered with a thin gold layer. The samples were aligned with respect to the beam by detecting backscattered He+ ions with the initial energy of 2 MeV. The ordered pattern of the porous alumina films was successfully transferred into SiO2 after irradiation with a 4 MeV Cl2+ beam at fluence of 10(14) ions/cm(2), followed by chemical etching in a 5% HF solution.
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| 7. |
- Razpet, A., et al.
(författare)
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Ion transmission and characterization of ordered nanoporous alumina
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; B:222, s. 593-600
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Tidskriftsartikel (refereegranskat)abstract
- Ordered nanoporous alumina samples with a pore diameter of 70 nm, an array period of 100 nm and several thicknesses were considered as possible masks for pattern transfer by MeV ion lithography. A simple procedure for the sample alignment using a 2 MeV He+ beam was utilized. The energy distributions of transmitted ions as well as backscattering spectra were studied in aligned and non-aligned orientations. The best transmission, comparable to the relative surface area covered by pores, was reached for 2 mum thick samples and was independent on ion species. Although the transmission for thicker membranes was generally lower, it significantly depended on the quality of each individual sample. The presented ion beam technique can therefore be used as a tool for the characterization of porous materials. The acceptance angle for transmission through pores and the effective atomic density of samples can be obtained from the experimental data and it is shown that nanoporous alumina can be used as a mask for MeV ion lithography.
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