| 1. |
- Appelfeller, Stephan, et al.
(författare)
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Continuous crossover from two-dimensional to one-dimensional electronic properties for metallic silicide nanowires
- 2020
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Ingår i: Physical Review B. - 2469-9950. ; 102:11
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Tidskriftsartikel (refereegranskat)abstract
- In a joint experimental and theoretical study on metallic TbSi2 nanowires, we observe a continuous crossover from a two-dimensional (2D) to a quasi-one-dimensional (1D) electronic structure by reduction of the nanowire width. The nanowires were grown by self-organization on vicinal Si(111) substrates denoted by the Miller indices (hhk). Their electronic structure was analyzed by angle-resolved photoemission spectroscopy (ARPES) and calculated using density functional theory (DFT). In ARPES, the TbSi2 nanowires show basically the 2D electronic structure of the TbSi2 film on planar Si(111) with an increasing momentum broadening for decreasing nanowire widths, consistent with Heisenberg's uncertainty principle. In contrast, DFT calculations predict a purely 1D electronic structure for TbSi2 nanowires. Unfolding this 1D electronic structure onto the Brillouin zone of the TbSi2 film leads to a Fermi surface appearing similar to the one of the 2D TbSi2 film, but with an additional 1D contribution from nanowire edges. Such an additional 1D signature is also observed in ARPES for narrow nanowires. These results indicate a continuous transition to a 1D electronic structure for decreasing nanowire widths.
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| 2. |
- Appelfeller, Stephan, et al.
(författare)
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Self-organized formation of unidirectional and quasi-one-dimensional metallic Tb silicide nanowires on Si(110)
- 2023
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 607
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Tidskriftsartikel (refereegranskat)abstract
- Terbium induced nanostructures on Si(110) and their growth are thoroughly characterized by low energy electron diffraction, scanning tunneling microscopy and spectroscopy, core-level and valence band photoelectron spectroscopy, and angle-resolved photoelectron spectroscopy. For low Tb coverage, a wetting layer forms with its surface fraction continuously decreasing with increasing Tb coverage in favor of the formation of unidirectional Tb silicide nanowires. These nanowires show high aspect ratios for high annealing temperatures or on substrates already containing Tb in the bulk. Both wetting layer and nanowires are stable for temperatures up to 750°C. In contrast to the nanowires, the wetting layer is characterized by a band gap. Thus, the metallic nanowires, which show a quasi-one-dimensional electronic band structure, are embedded in a semiconducting surrounding of wetting layer and substrate, insulating the nanowires from each other.
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| 3. |
- Neuwirth, Christoph, et al.
(författare)
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Implementing Motor Unit Number Index (MUNIX) in a large clinical trial : Real world experience from 27 centres
- 2018
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Ingår i: Clinical Neurophysiology. - : Elsevier. - 1388-2457 .- 1872-8952. ; 129:8, s. 1756-1762
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Motor Unit Number Index (MUNIX) is a quantitative neurophysiological method that reflects loss of motor neurons in Amyotrophic Lateral Sclerosis (ALS) in longitudinal studies. It has been utilized in one natural history ALS study and one drug trial (Biogen USA) after training and qualification of raters.METHODS: Prior to testing patients, evaluators had to submit test-retest data of 4 healthy volunteers. Twenty-seven centres with 36 raters measured MUNIX in 4 sets of 6 different muscles twice. Coefficient of variation of all measurements had to be <20% to pass the qualification process. MUNIX COV of the first attempt, number of repeated measurements and muscle specific COV were evaluated.RESULTS: COV varied considerably between raters. Mean COV of all raters at the first measurements was 12.9% ± 13.5 (median 8.7%). Need of repetitions ranged from 0 to 43 (mean 10.7 ± 9.1, median 8). Biceps and first dorsal interosseus muscles showed highest repetition rates. MUNIX variability correlated considerably with variability of compound muscle action potential.CONCLUSION: MUNIX revealed generally good reliability, but was rater dependent and ongoing support for raters was needed.SIGNIFICANCE: MUNIX can be implemented in large clinical trials as an outcome measure after training and a qualification process.
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