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Schmidt, Florian, Dr.ORCID iD iconorcid.org/0000-0002-5065-7786
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Publications (10 of 71) Show all publications
Mousavi, S. M., Thorin, E., Schmidt, F., Sepman, A., Bai, X.-S. & Fatehi, H. (2023). Numerical study and experimental verification of biomass conversion and potassium release in a 140 kW entrained flow gasifier. Energy & Fuels, 37(2), 1116-1130
Open this publication in new window or tab >>Numerical study and experimental verification of biomass conversion and potassium release in a 140 kW entrained flow gasifier
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2023 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 37, no 2, p. 1116-1130Article in journal (Refereed) Published
Abstract [en]

In this study, a Eulerian–Lagrangian model is used to study biomass gasification and release of potassium species in a 140 kW atmospheric entrained flow gasifier (EFG). Experimental measurements of water concentration and temperature inside the reactor, together with the gas composition at the gasifier outlet, are used to validate the model. For the first time, a detailed K-release model is used to predict the concentrations of gas-phase K species inside the gasifier, and the results are compared with experimental measurements from an optical port in the EFG. The prediction errors for atomic potassium (K), potassium chloride (KCl), potassium hydroxide (KOH), and total potassium are 1.4%, 9.8%, 5.5%, and 5.7%, respectively, which are within the uncertainty limits of the measurements. The numerical model is used to identify and study the main phenomena that occur in different zones of the gasifier. Five zones are identified in which drying, pyrolysis, combustion, recirculation, and gasification are active. The model was then used to study the transformation and release of different K species from biomass particles. It was found that, for the forest residue fuel that was used in the present study, the organic part of K is released at the shortest residence time, followed by the release of inorganic K at higher residence times. The release of inorganic salts starts by evaporation of KCl and continues by dissociation of K2CO3 and K2SO4, which forms gas-phase KOH. The major fraction of K is released around the combustion zone (around 0.7–1.3 m downstream of the inlet) due to the high H2O concentration and temperature. These conditions lead to rapid dissociation of K2CO3 and K2SO4, which increases the total K concentration from 336 to 510 ppm in the combustion zone. The dissociation of the inorganic salts and KOH formation continues in the gasification zone at a lower rate; hence, the total K concentration slowly increases from 510 ppm at 1.3 m to 561 ppm at the outlet.

National Category
Energy Engineering Chemical Process Engineering Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-202444 (URN)10.1021/acs.energyfuels.2c03107 (DOI)000924910900001 ()36705624 (PubMedID)2-s2.0-85146130812 (Scopus ID)
Funder
Swedish Energy Agency, 22538-4The Kempe Foundations, JCK-1316Knut and Alice Wallenberg FoundationEU, Horizon 2020, 637020Swedish Energy Agency, 50470-1Swedish Energy Agency, 36160-1Bio4Energy
Available from: 2023-01-10 Created: 2023-01-10 Last updated: 2023-09-05Bibliographically approved
Thorin, E., Maia Paiva, E. & Schmidt, F. (2023). Quantitative tomographic laser absorption imaging of atomic potassium during combustion of potassium chloride salt and biomass. Analytical Chemistry, 95(2), 1140-1148
Open this publication in new window or tab >>Quantitative tomographic laser absorption imaging of atomic potassium during combustion of potassium chloride salt and biomass
2023 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 95, no 2, p. 1140-1148Article in journal (Refereed) Published
Abstract [en]

Gaseous potassium (K) species play an important role in biomass combustion processes, and imaging techniques are powerful tools to investigate the related gas-phase chemistry. Here, laser absorption imaging of gaseous atomic K in flames is implemented using tunable diode laser absorption spectroscopy at 769.9 nm and a high-speed complementary metal oxide semiconductor (CMOS) camera recording at 30 kfps. Atomic K absorption spectra are acquired for each camera pixel in a field of view of 28 × 28 mm at a rate of 100 Hz. The technique is used to determine the spatial distribution of atomic K concentration during the conversion of potassium chloride (KCl) salt and wheat straw particles in a laminar premixed CH4/air flame with an image pixel resolution of up to 120 μm. Due to axisymmetry in setup geometry and, consequently, atomic K distributions, the radial atomic K concentration fields could be reconstructed by one-dimensional tomography. For the KCl sample, the K concentration field was in excellent agreement with previous point measurements. In the case of wheat straw, atomic K concentrations of around 3 ppm were observed in a cylindrical flame during devolatilization. In the char conversion phase, a spherical layer of atomic K, with concentrations reaching 25 ppm, was found within 5 mm of the particle surface, while the concentration rapidly decreased to sub-ppm levels along the vertical axis. In both cases, a thin (∼1 mm) layer without any atomic K was observed in close vicinity to the particle, suggesting that the potassium was initially not released in its atomic form.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
Keywords
Absorption, Biomass, Lasers, Potassium, Tomography
National Category
Atom and Molecular Physics and Optics Inorganic Chemistry Chemical Process Engineering Energy Engineering
Identifiers
urn:nbn:se:umu:diva-202359 (URN)10.1021/acs.analchem.2c03890 (DOI)000907828300001 ()36584277 (PubMedID)2-s2.0-85145461360 (Scopus ID)
Funder
Swedish Energy Agency, 36160-1The Kempe Foundations, JCK-1316The Kempe Foundations, JCK-2025Umeå UniversityBio4Energy
Available from: 2023-01-09 Created: 2023-01-09 Last updated: 2023-04-27Bibliographically approved
Maia Paiva, E. & Schmidt, F. (2023). Widefield mid-infrared photothermal heterodyne imaging in the cell-silent window. In: Ji-Xin Cheng; Wei Min; Garth J. Simpson (Ed.), Advanced chemical microscopy for life science and translational medicine 2023: . Paper presented at SPIE BIOS, San Francisco, Californa, USA, January 28 - February 3, 2023. SPIE Digital Library, Article ID 1239207.
Open this publication in new window or tab >>Widefield mid-infrared photothermal heterodyne imaging in the cell-silent window
2023 (English)In: Advanced chemical microscopy for life science and translational medicine 2023 / [ed] Ji-Xin Cheng; Wei Min; Garth J. Simpson, SPIE Digital Library , 2023, article id 1239207Conference paper, Published paper (Refereed)
Abstract [en]

Widefield mid-infrared photothermal heterodyne (WIPH) microscopy enables sensitive and fast chemical imaging with high spatial resolution. The technique is realized using an external-cavity quantum cascade laser emitting and a digital frequency-domain lock-in filter for simultaneous multi-harmonic demodulation of WIPH signals recorded by individual camera pixels at a frame rate of 20 kHz. The filter allows the use of continuous-wave probe light and the time-resolved detection of photothermal decay curves. The microscope provides <1 µm spatial resolution in a 64x64 µm field of view. Here, we present preliminary results from hyperspectral WIPH imaging of alkyne-tagged palmitic acid (PA), azidetagged PA and perdeuterated PA via their absorption features in the cell-silent spectral region around 2100 cm-1. The alkyne and azide functional groups and deuterium are promising vibrational probes for selective imaging of biomolecules, such as lipids and proteins, in cells.

Place, publisher, year, edition, pages
SPIE Digital Library, 2023
National Category
Atom and Molecular Physics and Optics Analytical Chemistry Medical Engineering
Identifiers
urn:nbn:se:umu:diva-205830 (URN)10.1117/12.2654181 (DOI)2-s2.0-85159790180 (Scopus ID)
Conference
SPIE BIOS, San Francisco, Californa, USA, January 28 - February 3, 2023
Funder
The Kempe FoundationsSwedish Research CouncilUmeå University
Available from: 2023-03-21 Created: 2023-03-21 Last updated: 2023-06-21Bibliographically approved
Sepman, A., Thorin, E., Ögren, Y., Ma, C., Carlborg, M., Wennebro, J., . . . Schmidt, F. M. (2022). Laser-based detection of methane and soot during entrained-flow biomass gasification. Combustion and Flame, 237, Article ID 111886.
Open this publication in new window or tab >>Laser-based detection of methane and soot during entrained-flow biomass gasification
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2022 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 237, article id 111886Article in journal (Refereed) Published
Abstract [en]

Methane is one of the main gas species produced during biomass gasification and may be a desired or undesired product. Syngas CH4 concentrations are typically >5 vol-% (when desired) and 1–3 vol-% even when efforts are made to minimize it, while thermochemical equilibrium calculations (TEC) predict complete CH4 decomposition. How CH4 is generated and sustained in the reactor core is not well understood. To investigate this, accurate quantification of the CH4 concentration during the process is a necessary first step. We present results from rapid in situ measurements of CH4, soot volume fraction, H2O and gas temperature in the reactor core of an atmospheric entrained-flow biomass gasifier, obtained using tunable diode laser absorption spectroscopy (TDLAS) in the near-infrared (1.4 µm) and mid-infrared (3.1 µm) region. An 80/20 wt% mixture of forest residues and wheat straw was converted using oxygen-enriched air (O2>21 vol%) as oxidizer, while the global air-fuel equivalence ratio (AFR) was set to values between 0.3 and 0.7. Combustion at AFR 1.3 was performed as a reference. The results show that the CH4 concentration increased from 1 to 3 vol-% with decreasing AFR, and strongly correlated with soot production. In general, the TDLAS measurements are in good agreement with extractive diagnostics at the reactor outlet and TEC under fuel-lean conditions, but deviate significantly for lower AFR. Detailed 0D chemical reaction kinetics simulations suggest that the CH4 produced in the upper part of the reactor at temperatures >1700 K was fully decomposed, while the CH4 in the final syngas originated from the pyrolysis of fuel particles at temperatures below 1400 K in the lower section of the reactor core. It is shown that the process efficiency was significantly reduced due to the C and H atoms bound in methane and soot.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Entrained-flow reactor, Gasification, Biomass, Methane, Soot, Tunable diode laser absorption spectroscopy (TDLAS)
National Category
Energy Engineering Renewable Bioenergy Research Atom and Molecular Physics and Optics Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-190099 (URN)10.1016/j.combustflame.2021.111886 (DOI)000735780800001 ()2-s2.0-85120458898 (Scopus ID)
Funder
EU, Horizon Europe, 637020Swedish Energy Agency, 50470-1Bio4Energy
Available from: 2021-12-06 Created: 2021-12-06 Last updated: 2023-09-05Bibliographically approved
Thorin, E., Maia Paiva, E., Broström, M. & Schmidt, F. (2022). Quantitative imaging of K species in biomass combustion. In: Markus Broström (Ed.), Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment: . Paper presented at The 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022,. Department of Applied Physics and Electronics, Umeå University
Open this publication in new window or tab >>Quantitative imaging of K species in biomass combustion
2022 (English)In: Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment / [ed] Markus Broström, Department of Applied Physics and Electronics, Umeå University , 2022Conference paper, Published paper (Other academic)
Abstract [en]

Laser absorption imaging (LAI) has been applied for quantitative tomographic imaging of theatomic potassium (K) distribution during conversion of KCl salt and biomass samples in alaboratory burner. For biomass, the atomic K distributions were significantly different between thedevolatilization and char burning phases. Furthermore, we demonstrate LAI combined withphotofragmentation (PF-LAI) for simultaneous imaging of all three species, atomic K, potassiumhydroxide (KOH) and potassium chloride (KCl), albeit with reduced field of view. The high cameraframe rate (1 MHz) enabled resolving the post-fragmentation recombination of the K fragments,which opens up for spatially and temporally resolved reaction kinetics experiments. 

Place, publisher, year, edition, pages
Department of Applied Physics and Electronics, Umeå University, 2022
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-199666 (URN)
Conference
The 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022,
Note

Session 10. Diagnostics. 

Proceedings published on USB. 

Available from: 2022-09-26 Created: 2022-09-26 Last updated: 2022-10-05Bibliographically approved
Thorin, E., Sepman, A., Ögren, Y., Ma, C., Carlborg, M., Wennebro, J., . . . Schmidt, F. (2022). Quantitative real-time in situ measurement of gaseous K, KOH and KCl in a 140 kW entrained-flow biomass gasifier. Proceedings of the Combustion Institute
Open this publication in new window or tab >>Quantitative real-time in situ measurement of gaseous K, KOH and KCl in a 140 kW entrained-flow biomass gasifier
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2022 (English)In: Proceedings of the Combustion Institute, ISSN 1540-7489, E-ISSN 1873-2704Article in journal (Refereed) In press
Abstract [en]

Photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) was used to simultaneously measure the concentrations of gas phase atomic potassium (K), potassium hydroxide (KOH) and potassium chloride (KCl) in the reactor core of a 140 kWth atmospheric entrained-flow gasifier (EFG). In two gasification experiments at air-to-fuel equivalence ratio of 0.5, the EFG was first run on forest residues (FR) and then on an 80/20 mixture of FR and wheat straw (FR/WS). Combustion at air-to-fuel equivalence ratio of 1.3 was investigated for comparison. A high K(g) absorbance was observed in gasification, requiring the photofragmentation signals from KOH(g) and KCl(g) to be recorded at a fixed detuning of 7.3 cm−1 from the center of the K(g) absorption profile. In combustion, the fragments recombined instantly after the UV pulse within around 10 µs, whereas in gasification, the K(g) fragment concentration first increased further for 30 µs after the UV pulse, before slowly decaying for up to hundreds of µs. According to 0D reaction kinetics simulations, this could be explained by a difference in recombination kinetics, which is dominated by oxygen reactions in combustion and by hydrogen reactions in gasification. The K species concentrations in the EFG were stable on average, but periodic short-term variations due to fuel feeding were observed, as well as a gradual increase in KOH(g) over the day as the reactor approached global equilibrium. A comparison of the average K species concentrations towards the end of each experiment showed a higher total K in the gas phase for FR/WS, with higher K(g) and KCl(g), but lower KOH(g), compared to the FR fuel. The measured values were in reasonable agreement with predictions by thermodynamic equilibrium calculations.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Biomass, Entrained-flow gasification, Potassium (K), Photofragmentation, Tunable diode laser absorption spectroscopy (TDLAS)
National Category
Other Physics Topics Atom and Molecular Physics and Optics Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-199816 (URN)10.1016/j.proci.2022.07.180 (DOI)001019037700001 ()2-s2.0-85139508080 (Scopus ID)
Funder
Bio4EnergyThe Kempe Foundations, JCK-1316Swedish Energy Agency, 50470-1Swedish Energy Agency, 36160-1EU, Horizon 2020, 637020
Available from: 2022-09-29 Created: 2022-09-29 Last updated: 2023-09-05
Thorin, E., Alexey, S., Broström, M. & Schmidt, F. (2022). Real-time in situ quantification of gaseous K, KOH and KCl in biomass combustion and gasification. In: Markus Broström (Ed.), Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment: . Paper presented at The 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022. Department of Applied Physics and Electronics, Umeå University
Open this publication in new window or tab >>Real-time in situ quantification of gaseous K, KOH and KCl in biomass combustion and gasification
2022 (English)In: Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment / [ed] Markus Broström, Department of Applied Physics and Electronics, Umeå University , 2022Conference paper, Published paper (Other academic)
Abstract [en]

Photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) has been developedfor simultaneous, quantitative detection of the major potassium species during biomass combustionand gasification: atomic potassium, potassium hydroxide and potassium chloride. PF-TDLAS hasbeen used for experiments in lab-scale to pilot-scale applications, and results were compared tonumerical simulations. Deviations between experiments and simulations suggest that more work isneeded on the numerical models, where PF-TDLAS can provide data for validation.

Place, publisher, year, edition, pages
Department of Applied Physics and Electronics, Umeå University, 2022
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-199685 (URN)
Conference
The 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022
Note

Session 10. Diagnostics. 

Proceedings published on USB. 

Available from: 2022-09-26 Created: 2022-09-26 Last updated: 2022-10-05Bibliographically approved
Maia Paiva, E. & Schmidt, F. (2022). Ultrafast widefield mid-infrared photothermal heterodyne imaging. Analytical Chemistry, 94(41), 14242-14250
Open this publication in new window or tab >>Ultrafast widefield mid-infrared photothermal heterodyne imaging
2022 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 94, no 41, p. 14242-14250Article in journal (Refereed) Published
Abstract [en]

Mid-infrared photothermal (MIP) microscopy is a valuable tool for sensitive and fast chemical imaging with high spatial resolution beyond the mid-infrared diffraction limit. The highest sensitivity is usually achieved with heterodyne MIP employing photodetector point-scans and lock-in detection, while the fastest systems use camera-based widefield MIP with pulsed probe light. One challenge is to simultaneously achieve high sensitivity, spatial resolution, and speed in a large field of view. Here, we present widefield mid-infrared photothermal heterodyne (WIPH) imaging, where a digital frequency-domain lock-in (DFdLi) filter is used for simultaneous multiharmonic demodulation of MIP signals recorded by individual camera pixels at frame rates up to 200 kHz. The DFdLi filter enables the use of continuous-wave probe light, which, in turn, eliminates the need for synchronization schemes and allows measuring MIP decay curves. The WIPH approach is characterized by imaging potassium ferricyanide microparticles and applied to detect lipid droplets (alkyne-palmitic acid) in 3T3-L1 fibroblast cells, both in the cell-silent spectral region around 2100 cm–1 using an external-cavity quantum cascade laser. The system achieved up to 4000 WIPH images per second at a signal-to-noise ratio of 5.52 and 1 μm spatial resolution in a 128 × 128 μm field of view. The technique opens up for real-time chemical imaging of fast processes in biology, medicine, and material science.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2022
National Category
Atom and Molecular Physics and Optics Physiology Medical Biotechnology
Identifiers
urn:nbn:se:umu:diva-200053 (URN)10.1021/acs.analchem.2c02548 (DOI)000869785200001 ()36197677 (PubMedID)2-s2.0-85139515013 (Scopus ID)
Funder
The Kempe Foundations, JCK_2025Umeå University
Available from: 2022-10-06 Created: 2022-10-06 Last updated: 2023-09-05Bibliographically approved
Qu, Z., Fatehi, H. & Schmidt, F. (2021). Potassium Release from Biomass Particles during Combustion - Real-Time In Situ TDLAS Detection and Numerical Simulation. Applied Sciences, 11(19), Article ID 8887.
Open this publication in new window or tab >>Potassium Release from Biomass Particles during Combustion - Real-Time In Situ TDLAS Detection and Numerical Simulation
2021 (English)In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 19, article id 8887Article in journal (Refereed) Published
Abstract [en]

Potassium (K) is one of the main and most hazardous trace species released to the gas-phase during thermochemical conversion of biomass. Accurate experimental data and models of K release are needed to better understand the chemistry involved. Tunable diode laser absorption spectroscopy (TDLAS) is used for simultaneous real-time in situ measurements of gas-phase atomic K, water (H2O) and gas temperature in the vicinity (boundary layer) of biomass particles during combustion in a laboratory single-particle reactor. Atomic K is detected in a wide dynamic range, including optically thick conditions, using direct absorption spectroscopy at the wavelength of 770 nm, while H2O and temperature are determined by calibration-free scanned wavelength modulation spectroscopy at 1398 nm. The high accuracy and repeatability of the setup allows to distinguish measurements with varying initial particle mass, laser beam height above the particle and fuel type. Four types of biomass with different ash composition are investigated: softwood, Salix, Miscanthus and wheat straw. For Salix and wheat straw, the K release behaviour is, for the first time, compared to a detailed numerical particle model taking into account the interaction between K/S/Cl composition in the particle ash. A good agreement is achieved between the measured and calculated time-resolved atomic K concentrations for the devolatilization phase of the biomass particles. 

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
potassium (K), biomass, combustion, laser spectroscopy, TDLAS, numerical particle model
National Category
Atom and Molecular Physics and Optics Inorganic Chemistry Chemical Process Engineering Renewable Bioenergy Research
Identifiers
urn:nbn:se:umu:diva-187992 (URN)10.3390/app11198887 (DOI)000708178800001 ()2-s2.0-85115743471 (Scopus ID)
Funder
Swedish Energy Agency, 36160-1, 22538-4The Kempe Foundations, JCK-1316Bio4EnergySwedish National Infrastructure for Computing (SNIC)
Available from: 2021-09-30 Created: 2021-09-30 Last updated: 2023-09-05Bibliographically approved
Thorin, E., Zhang, K., Valiev, D. & Schmidt, F. M. (2021). Simultaneous detection of K, KOH, and KCl in flames and released from biomass using photofragmentation TDLAS. Optics Express, 29(26), Article ID 42945.
Open this publication in new window or tab >>Simultaneous detection of K, KOH, and KCl in flames and released from biomass using photofragmentation TDLAS
2021 (English)In: Optics Express, E-ISSN 1094-4087, Vol. 29, no 26, article id 42945Article in journal (Refereed) Published
Abstract [en]

Gaseous potassium (K) species released from biomass during thermochemicalconversion pose challenges to reactors and human health. Photofragmentation tunable diodelaser absorption spectroscopy (PF-TDLAS) was used for simultaneous, high-dynamic rangemeasurements of atomic K, potassium hydroxide (KOH) and potassium chloride (KCl) inflat flames seeded with KCl salt. An expression for the PF-TDLAS signal is presented andexperimentally verified. Axial K species concentration profiles recorded at fuel-air equivalenceratios of 0.8 and 1.3 are compared to 2D axisymmetric reacting flow simulations. An overallgood agreement is found, but KOH is over-predicted in simulations of fuel-rich flames at theexpense of atomic K. Quantification of K species close to softwood and wheat straw particlesconverted in the flames is demonstrated.

Place, publisher, year, edition, pages
The Optical Society, 2021
Keywords
potassium (K), potassium hydroxide (KOH), potassium chloride (KCl), photofragmentation, optical sensors, tunable diode laser absorption spectroscopy, biomass
National Category
Atom and Molecular Physics and Optics Energy Engineering Renewable Bioenergy Research
Identifiers
urn:nbn:se:umu:diva-190194 (URN)10.1364/oe.446725 (DOI)000730136600051 ()2-s2.0-85120900645 (Scopus ID)
Funder
Swedish Energy Agency, 36160-1The Kempe Foundations, JCK-1316Swedish Research Council, 2018-05973Bio4Energy
Available from: 2021-12-09 Created: 2021-12-09 Last updated: 2024-01-19Bibliographically approved
Projects
Quantum cascade laser system for real-time measurements of 12CO and 13CO carbon monoxide isotopoloques in exhaled breath [2013-06031_VR]; Umeå University
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5065-7786

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