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- Ghorbani, Ramin, 1981-
(författare)
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Real-time breath gas analysis of carbon monoxide : laser-based detection and pulmonary gas exchange modeling
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Breath gas analysis is a promising approach for non-invasive medical diagnostics and physiological monitoring. Real-time, breath-cycle resolved biomarker detection facilitates data interpretation and has the potential to improve the diagnostic value of breath tests as exhalation profiles carry spatiotemporal information about biomarker origin and gas exchange in the respiratory tract. This thesis presents and scrutinizes a novel methodology for the analysis of real-time breath data, where single-exhalation profiles are simulated using a pulmonary gas exchange model and least-squares fitted to measured expirograms to extract airway and alveolar contributions and diffusing capacities. The methodology is demonstrated on exhaled breath carbon monoxide (eCO), a candidate biomarker for oxidative stress and respiratory diseases. The thesis mainly covers (1) the construction of a compact optical sensor based on tunable diode laser absorption spectroscopy (TDLAS) in the mid-infrared region (4.7 μm) for selective and precise real-time detection of CO in breath and ambient air (detection limit 9 ± 5 ppb at 0.1 s), (2) the design of an advanced online breath sampling system, (3) the implementation of a trumpet model with axial diffusion (TMAD) to simulate the CO gas exchange, and (4) the application of extended eCO analysis in clinical studies to establish the healthy non-smoker baseline of the eCO parameters and to study the response to CO and wood smoke exposure. It is shown that the TMAD adequately describes the gas exchange during systemic CO elimination for different breathing patterns, and that there is no difference between eCO parameters from mouth- and nose exhalations. Expirogram shape and eCO parameters exhibit a dependence on the exhalation flow rate, but for a given breathing maneuverer, the parameters lie in a narrow range. Airway CO is close to and correlates with ambient air CO, indicating negligible airway production in the healthy population. The alveolar diffusing capacity is independent of endogenous CO, even after exposure to elevated exogenous CO, and could be used to assess lung diffusion abnormalities. Compared to CO exposure, no clear additional effect of exposure to wood smoke particles on eCO is observed. The discrimination between endogenous and exogenous CO sources remains a challenge.
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| 2. |
- Schmidt, Johann, 1989-
(författare)
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Topological superconductivity in multiorbital materials
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Multiorbital materials add a new intricacy to the already complex phenomenon of superconductivity. The additional orbital degree of freedom requires leaving behind the established band picture, but also opens the possibility of more complicated order parameters with new properties. This thesis summarizes theoretical studies of two examples of multiorbital superconductors.The first part focuses on superconductivity in Kitaev materials. The unusual interactions in these materials are shown to give rise to spin triplet superconducting pairing on both two-and three-dimensional lattice structures. A symmetry characterization enables the analysis of the stable superconducting order parameters, revealing several nodal states on the 3D harmonic honeycomb lattices and a competition between nematic and chiral superconductivity on the 2D honeycomb lattice. The following topological classification uncovers a number of topologically non-trivial superconducting states protected by various symmetries, giving rise to flat bands, Fermi arcs, or dispersing Majorana excitations on their surface.The thesis’ second part spotlights odd-frequency superconductivity in a doped topological insulator. An experimentally supported uncommon interorbital order parameter gives rise to large intraorbital odd-frequency pairing. A calculation of the Meissner effect unveils an unexpected diamagnetic odd-frequency Meissner response, stabilizing superconductivity.The results of this thesis highlight the diverse nature of superconductivity in multiorbitalmaterials and stimulate further research on its topological properties and stability.
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