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| 2. |
- Balmer, Richard S., et al.
(författare)
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Transport behavior of holes in boron delta-doped diamond structures
- 2013
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 113:3, s. 033702-
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Tidskriftsartikel (refereegranskat)abstract
- Boron delta-doped diamond structures have been synthesized using microwave plasma chemical vapor deposition and fabricated into FET and gated Hall bar devices for assessment of the electrical characteristics. A detailed study of variable temperature Hall, conductivity, and field-effect mobility measurements was completed. This was supported by Schrodinger-Poisson and relaxation time calculations based upon application of Fermi's golden rule. A two carrier-type model was developed with an activation energy of similar to 0.2 eV between the delta layer lowest subband with mobility similar to 1 cm(2)/Vs and the bulk valence band with high mobility. This new understanding of the transport of holes in such boron delta-doped structures has shown that although Hall mobility as high as 900 cm(2)/Vs was measured at room temperature, this dramatically overstates the actual useful performance of the device.
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| 3. |
- Bell, E., et al.
(författare)
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Biogeochemical cycling by a low-diversity microbial community in deep groundwater
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 9:SEP
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Tidskriftsartikel (refereegranskat)abstract
- Olkiluoto, an island on the south-west coast of Finland, will host a deep geological repository for the storage of spent nuclear fuel. Microbially induced corrosion from the generation of sulphide is therefore a concern as it could potentially compromise the longevity of the copper waste canisters. Groundwater at Olkiluoto is geochemically stratified with depth and elevated concentrations of sulphide are observed when sulphate-rich and methane-rich groundwaters mix. Particularly high sulphide is observed in methane-rich groundwater from a fracture at 530.6 mbsl, where mixing with sulphate-rich groundwater occurred as the result of an open drill hole connecting two different fractures at different depths. To determine the electron donors fuelling sulphidogenesis, we combined geochemical, isotopic, metagenomic and metaproteomic analyses. This revealed a low diversity microbial community fuelled by hydrogen and organic carbon. Sulphur and carbon isotopes of sulphate and dissolved inorganic carbon, respectively, confirmed that sulphate reduction was ongoing and that CO2 came from the degradation of organic matter. The results demonstrate the impact of introducing sulphate to a methane-rich groundwater with limited electron acceptors and provide insight into extant metabolisms in the terrestrial subsurface.
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| 5. |
- Rashid, S. J., et al.
(författare)
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Numerical Parameterization of Chemical-Vapor-Deposited (CVD) Single-Crystal Diamond for Device Simulation and Analysis
- 2008
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Ingår i: IEEE Transactions on Electron Devices. - 0018-9383 .- 1557-9646. ; 55:10, s. 2744-2756
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Tidskriftsartikel (refereegranskat)abstract
- High-quality electronic-grade intrinsic chemical-vapor-deposited (CVD) single-crystal diamond layers having exceptionally high carrier mobilities have been reported by Isberg et al. This makes the realization of novel electronic devices in diamond, particularly for high-voltage and high-temperature applications, a viable proposition. As such, material models which can capture the particular features of diamond as a semiconductor are required to analyze, optimize, and quantitatively design new devices. For example, the incomplete ionization of boron in diamond and the transition to metallic conduction in heavily boron-doped layers require accurate carrier freeze-out models to be included in the simulation of diamond devices. Models describing these phenomena are proposed in this paper and include numerical approximation of intrinsic diamond which is necessary to formulate doping- and temperature-dependent mobility models. They enable a concise numerical description of single-crystal diamond which agrees with data obtained from material characterization. The models are verified by application to new Schottky m-i-p(+) diode structures in diamond. Simulated forward characteristics show excellent correlation with experimental measurements. In spite of the lack of impact ionization data for single-crystal diamond, approximation of avalanche coefficient parameters from other wide-bandgap semiconductors has also enabled the reverse blocking characteristics of diamond diodes to be simulated. Acceptable agreement with breakdown voltage from experimental devices made with presently available single-crystal CVD diamond is obtained.
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| 6. |
- Erlendsson, Lýður S, et al.
(författare)
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Barley as a green factory for the production of functional Flt3 ligand
- 2009
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Ingår i: Biotechnology Journal. - Weinheim : Wiley-VCH Verlag GmbH & Co. KGaA. - 1860-7314 .- 1860-6768. ; 5:2, s. 163-171
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Tidskriftsartikel (refereegranskat)abstract
- Biologically active recombinant human Flt3 ligand was expressed and isolated from transgenic barley seeds. Its expression is controlled by a tissue specific promoter that confines accumulation of the recombinant protein to the endosperm tissue of the seed. The recombinant Flt3 ligand variant expressed in the seeds contains an HQ-tag for affinity purification on immobilized metal ion affinity chromatography (IMAC) resin. The tagged protein was purified from seed extracts to near homogeneity using sequential chromatography on IMAC affinity resin and cation exchange resin. We also show that the recombinant Flt3 ligand protein undergoes posttranslational modifications: it is a glycoprotein containing alpha-1,3-fucose and alpha-1,2-xylose. The HQ-tagged Flt3 ligand variant exhibits comparable biological activity to commercial Flt3 ligand. This is the first report showing expression and accumulation of recombinant human growth factor in barley seeds with a yield of active protein similar to a bacterial expression system. The present results demonstrate that plant molecular farming is a viable approach for the bioproduction of human-derived growth factors.
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