| 1. |
- Munch Roager, Henrik, et al.
(författare)
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Whole grain-rich diet reduces body weight and systemic low-grade inflammation without inducing major changes of the gut microbiome: A randomised cross-over trial
- 2019
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Ingår i: Gut. - : BMJ. - 1468-3288 .- 0017-5749. ; 68:1, s. 83-93
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Tidskriftsartikel (refereegranskat)abstract
- Objective T o investigate whether a whole grain diet alters the gut microbiome and insulin sensitivity, as well as biomarkers of metabolic health and gut functionality. Design 60 Danish adults at risk of developing metabolic syndrome were included in a randomised cross-over trial with two 8-week dietary intervention periods comprising whole grain diet and refined grain diet, separated by a washout period of =6 weeks. The response to the interventions on the gut microbiome composition and insulin sensitivity as well on measures of glucose and lipid metabolism, gut functionality, inflammatory markers, anthropometry and urine metabolomics were assessed. Results 50 participants completed both periods with a whole grain intake of 179±50 g/day and 13±10 g/day in the whole grain and refined grain period, respectively. Compliance was confirmed by a difference in plasma alkylresorcinols (p<0.0001). Compared with refined grain, whole grain did not significantly alter glucose homeostasis and did not induce major changes in the faecal microbiome. Also, breath hydrogen levels, plasma short-chain fatty acids, intestinal integrity and intestinal transit time were not affected. The whole grain diet did, however, compared with the refined grain diet, decrease body weight (p<0.0001), serum inflammatory markers, interleukin (IL)-6 (p=0.009) and C-reactive protein (p=0.003). The reduction in body weight was consistent with a reduction in energy intake, and IL-6 reduction was associated with the amount of whole grain consumed, in particular with intake of rye. Conclusion C ompared with refined grain diet, whole grain diet did not alter insulin sensitivity and gut microbiome but reduced body weight and systemic lowgrade inflammation.
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| 2. |
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| 3. |
- Pedersen, Henrik, 1981-, et al.
(författare)
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Chloride-based SiC epitaxial growth
- 2009
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Ingår i: Materials Science Forum Vols. 615-617. - : Trans Tech Publications. ; , s. 89-
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Konferensbidrag (refereegranskat)abstract
- Some aspects of the chloride-based CVD growth process have been investigated by using both the approach to add HCl to the standard precursors or/and by using the single molecule precursor methyltrichlorosilane (MTS). The efficiency of the process for different precursors, the growth rate stability and the effect that the Cl/Si-ratio has on the growth have been studied. MTS is showed to be the most efficient precursor; the growth can be hindered by to much chlorine in the gas mixture. The Cl/Si-ratio is also found to be a process parameter that affects the amount of incorporated nitrogen in the epilayers.
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| 4. |
- Stenberg, Pontus, 1984-, et al.
(författare)
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Matching precursor kinetics to afford a more robust CVD chemistry: a case study of the C chemistry for silicon carbide using SiF4 as Si precursor
- 2017
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 5, s. 5818-5823
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Tidskriftsartikel (refereegranskat)abstract
- Chemical Vapor Deposition (CVD) is one of the technology platforms forming the backbone of the semiconductor industry and is vital in the production of electronic devices. To upscale a CVD process from the lab to the fab, large area uniformity and high run-to-run reproducibility are needed. We show by a combination of experiments and gas phase kinetics modeling that the combinations of Si and C precursors with the most well-matched gas phase chemistry kinetics gives the largest area of of homoepitaxial growth of SiC. Comparing CH4, C2H4 and C3H8 as carbon precursors to the SiF4 silicon precursor, CH4 with the slowest kinetics renders the most robust CVD chemistry with large area epitaxial growth and low temperature sensitivity. We further show by quantum chemical modeling how the surface chemistry is impeded by the presence of F in the system which limits the amount of available surface sites for the C to adsorb.
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| 5. |
- Beyer, Franziska, 1980-, et al.
(författare)
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Defects in 4H-SiC Layers Grown by Chloride-based Epitaxy
- 2009
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Ingår i: Materials Science Forum Vols. 615-617. - : Trans Tech Publications. ; , s. 373-
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Konferensbidrag (refereegranskat)abstract
- Chloride-based 4H-SiC epitaxial layers were investigated by DLTS, MCTS and PL. The DLTS spectra of the as grown samples showed dominance of the Z1/2 and the EH6/7 peaks. For growth rates exceeding 100 µm/h, an additional peak occurred in the DLTS spectra which can be assigned to the UT1 defect. The shallow and the deep boron complexes as well as the HS1 defect are observed in MCTS measurements. The PL spectra are completely dominated by the near band gap (NBG) emission. No luminescence from donor-acceptor pair occurred. The PL line related to the D1 centre was weakly observed. In the NBG region nitrogen bound exciton (N-BE) and free exciton (FE) related lines could be seen. The addition of chlorine in the growth process gives the advantage of high growth rates without the introduction of additional defects.
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| 6. |
- Beyer, Franziska, et al.
(författare)
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Defects in low-energy electron-irradiated n-type 4H-SiC
- 2010
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Ingår i: Physica Scripta, vol. T141. - : IOP Publishing. ; , s. 014006-
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Konferensbidrag (refereegranskat)abstract
- The bistable M-center, previously observed in high-energy proton-implanted 4H-SiC, was detected in low-energy electron-irradiated 4H-SiC using deep-level transient spectroscopy (DLTS). Irradiation increased the DLTS signals of the intrinsic defects Z(1/2) and EH6/7 and introduced the frequently observed defects EH1 and EH3. After the M-center is annealed out at about 650K without bias and at about 575K with bias applied to the sample during the annealing process, a new bistable defect in the low temperature range of the DLTS spectrum, the EB-center, evolves. Since low-energy irradiation affects mainly the carbon atoms in SiC, the M-center and the newly discovered EB-center are most probably carbon-related intrinsic defects.
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| 7. |
- Blomqvist, A., et al.
(författare)
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Understanding the catalytic effects of H2S on CVD-growth of α-alumina : Thermodynamic gas-phase simulations and density functional theory
- 2011
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Ingår i: Proceedings of the 38th International Conference on Metallurgical Coatings and Thin Films (ICMCTF) — ICMCTF 2011. - : Elsevier BV. ; 206:7, s. 1771-1779
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Konferensbidrag (refereegranskat)abstract
- The catalytic effect of H2S on the AlCl3/H2/CO2/HCl chemical vapor deposition (CVD) process has been investigated on an atomistic scale. We apply a combined approach with thermodynamic modeling and density functional theory and show that H2S acts as mediator for the oxygenation of the Al-surface which will in turn increase the growth rate of Al2O3. Furthermore we suggest surface terminations for the three investigated surfaces. The oxygen surface is found to be hydrogenated, in agreement with a number of previous works. The aluminum surfaces are Cl-terminated in the studied CVD-process. Furthermore, we find that the AlClO molecule is a reactive transition state molecule which interacts strongly with the aluminum and oxygen surfaces.
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| 8. |
- Bombarda, F., et al.
(författare)
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Runaway electron beam control
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 61:1
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Carlsson, Patrick, 1975-, et al.
(författare)
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Photo-EPR Studies on Low-Energy Electron-irradiated 4H-SiC
- 2009
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Ingår i: Materials Science Forum, Vols. 615-617. - Materials Science Forum Vols. 615-617 : Trans Tech Publications. - 9780878493340 ; , s. 401-404
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Konferensbidrag (refereegranskat)abstract
- Photoexcitation electron paramagnetic resonance (photo-EPR) was used to determine deep levels related to the carbon vacancy (VC) in 4H-SiC. High-purity free-standing n-type 4H-SiC epilayers with concentration of intrinsic defects (except the photo-insensitive SI1 center) below the detection limit of EPR were irradiated with low-energy (200 keV) electrons to create mainly VC and defects related to the C sublattice. The simultaneous observation of and signals, their relative intensity changes and the absence of other defects in the sample provide a more straight and reliable interpretation of the photo-EPR results. The study suggests that the (+|0) level of VC is located at ~EC–1.77 eV in agreement with previously reported results and its single and double acceptor levels may be at ~ EC–0.8 eV and ~ EC–1.0 eV, respectively.
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| 10. |
- Choolakkal, Arun Haridas, 1992-
(författare)
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Conformal chemical vapor deposition of boron carbide thin films
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The sustainability goals of the modern world and the fascinating properties of sub-micron scale materials promote development of materials in thin film form. Thin films are materials that have thicknesses ranging from sub-nanometer to several micrometers, synthesized by various deposition techniques. They are used for diverse applications, such as light emitting diodes, solar cells, semiconductor chips, etc. The primary objective of this research project is to develop a chemical vapor deposition (CVD) process for conformal boron carbide thin films. Since boron carbide is a promising neutron converter material for solid-state neutron detectors, the process was validated by depositing on prototype detector chips. In this study, triethylboron (TEB) was used as single source CVD precursor to deposit boron carbide thin films. The initial experiments focused on low reaction rate deposition by depositing in a kinetically limited regime. The films deposited at ≤450 °C in 8:1 aspect ratio micro-trench structures were highly conformal and show a stoichiometry of about B5.2C. We attribute this observed conformality to the slow reaction kinetics of the TEB at the low deposition temperature enabling the diffusive transport of the precursor molecule down the trench. The depositions carried out on the prototype detector-chips show promising results. We expand our studies to investigate a new strategy with the prospect of improving the step coverage at higher temperatures for better film properties. We hypothesize that adding a suitable heavier molecule, diffusion additive, with an appropriate partial pressure can enhance the step coverage by pushing the lighter precursor molecule via competitive co-diffusion. It was tested by adding Xe gas to the boron carbide CVD from TEB. The result shows that with this diffusion additive the step coverage was improved from 0.71 to 0.97. From our experimental results, we suggest a competitive diffusion model that can be adapted to other CVD processes to enhance the film step coverage. The CVD process is further validated by depositing onto carbon nanotube membranes. The initial results show that the process was able to afford evenly deposition around the individual nanotubes in the carbon nanotube membrane. Raman spectroscopy measurements show a similar D-band to G-band intensity ratio before and after the deposition indicating that no defects were induced in the nanotubes.
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