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Kumar Wagri, N., Carlborg, M., Eriksson, M., Ma, C., Broström, M. & Andersson, B. M. (2023). High temperature interactions between coal ash and MgO-based refractories in lime kiln conditions. Fuel, 342, Article ID 127711.
Open this publication in new window or tab >>High temperature interactions between coal ash and MgO-based refractories in lime kiln conditions
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2023 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 342, article id 127711Article in journal (Refereed) Published
Abstract [en]

Magnesium oxide (MgO)-based refractories are commonly used in quicklime and cement rotary kilns. At the high temperatures in the kiln burn zone, the infiltration of molten fuel ash into the refractory can occur. Subsequent chemical interactions can cause refractory wear that inflicts high maintenance costs and loss of production. To improve refractory reliability, it is necessary to increase the understanding of the interactions between fuel ash slag and refractory liner materials. Three commercially available MgO-based refractory materials were exposed to coal ash at 1200 °C and 1400 °C for between 15 and 60 min under a CO2-rich gaseous environment. Hot slag from the coal ash infiltrated the refractories and the infiltration depths were estimated with scanning electron microscope with energy dispersive X-ray spectroscopy. Based on detailed elemental and microstructure analyses, the interactions between ash and refractory were examined. Molten silicates infiltrated the refractory through grain boundaries and pores into depths of up to 2.8 mm. Powder X-ray diffraction of the exposed refractory samples indicated that MgO grains reacted with SiO2-containing phases to form Mg2SiO4. This was identified as a corrosion product whose formation was supported by thermochemical equilibrium calculations. Elevated Mg content was found in the ash residue on top of the samples, indicating the dissolution or dislocation of refractory components. In addition, phases such as MgO were identified in the ash residue.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Coal ash, Lime kilns, MgO refractory, Refractory corrosion, Silicate slag, Slag infiltration
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-205464 (URN)10.1016/j.fuel.2023.127711 (DOI)000952980900001 ()2-s2.0-85149015295 (Scopus ID)
Funder
Bio4EnergySwedish Energy Agency
Available from: 2023-03-07 Created: 2023-03-07 Last updated: 2023-11-15Bibliographically approved
Kumar Wagri, N., Carlborg, M., Eriksson, M., Ma, C., Broström, M. & Andersson, B. M. (2023). High temperature interactions between K-rich biomass ash and MgO-based refractories. Journal of the European Ceramic Society, 43(8), 3770-3777
Open this publication in new window or tab >>High temperature interactions between K-rich biomass ash and MgO-based refractories
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2023 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 43, no 8, p. 3770-3777Article in journal (Refereed) Published
Abstract [en]

MgO-based refractories are used in lime kilns to withstand the high temperature and chemical environment. Efforts to reduce CO2 emissions have led to an increased interest to use bio-based fuels as alternatives to traditional fossil sources. The potential for refractory corrosion from a potassium-rich biomass ash was investigated by studying the infiltration of olive pomace ash into magnesia/spinel refractories. Refractory samples were exposed to the ash at up to 1400 °C for 15–60 min in a CO2–rich atmosphere. Molten ash infiltrated the refractories through pores and grain boundaries to a depth of up to 9.6 mm, which was quantified with a new systematic procedure. The phase KAlO2 was identified inside the refractories after exposure, indicating an attack of spinel components by potassium. Phases found in the ash residues also indicated the migration of refractory constituents. Thermochemical equilibrium calculations were also used to investigate the ash/refractory chemistry.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Biomass ash; Lime kiln; Magnesia; Olive pomace; Potassium; Refractory corrosion; Slag infiltration
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-205465 (URN)10.1016/j.jeurceramsoc.2023.01.058 (DOI)000955011500001 ()2-s2.0-85148748148 (Scopus ID)
Funder
Bio4EnergySwedish Energy Agency, 34721-3Swedish Energy Agency, 47198-1
Available from: 2023-03-07 Created: 2023-03-07 Last updated: 2023-11-15Bibliographically approved
Kumar Wagri, N., Carlborg, M., Eriksson, M., Ma, C., Broström, M. & Andersson, B. M. (2022). Interaction of olive pomace ash and coal ash with magnesium oxide based refractories. 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 >>Interaction of olive pomace ash and coal ash with magnesium oxide based refractories
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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]

In quicklime production, limestone is calcined at temperatures above 1000°C, depending on the desired product quality. Heat is supplied to the process from combustion inside the kilns that are insulated to reduce heat loss. The kilns are lined with insulating refractory bricks to withstand the hot, chemically aggressive, and mechanically abrasive environment. Magnesia bricks have emerged as well-performinglining materials, but they are still prone to extensive wear in kilns that are operated at higher temperatures. In particular, refractory corrosion can be caused by fuel ash infiltration that results inmaterial wear, which can incur high maintenance and operational costs through unplanned shutdowns of the kilns. At the same time, to reduce the release of fossil-based carbon to the atmosphere, it is of interest to introduce bio-based fuels into the kilns with only relatively small modifications to the process. Biobased waste streams from existing industries are preferable rather than biomass grown with the sole purpose of combustion. The ash content and properties of these types of waste residues do, however, tend to be problematic from a fuel ash chemistry point of view. Therefore, before introducing a new fuel, their potential effects on kiln lining material should be investigated. In this study, the infiltration of olivepomace ash and coal ash into commercially available refractory materials composed of mainly periclase(MgO) with minor amounts of spinel (MgAl2O4) were compared. They were exposed to the fuel ashes under a simulated lime kiln high CO2 atmosphere at 1200 and 1400°C for 15 and 60 minutes. The morphology and elemental composition of the exposed samples were investigated with scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. Ash-forming elements infiltrated the porous parts of the materials. The analytical results are complemented with thermodynamic equilibrium calculations to investigate the ash melting behavior. Crystalline phases in the residual ashes were investigated with X-ray diffraction. Refractory phases could be found in both ashes, indicating migration of refractory constituents. Olive pomace ash formed new crystalline compounds together with the refractory components whereas this was not observed for the coal ash, indicating that the former is more of a risk for material failure.  

Place, publisher, year, edition, pages
Department of Applied Physics and Electronics, Umeå University, 2022
Keywords
Coal ash, Olive pomace ash, MgO refractory, Corrosion, Slag intrusion, Potassium
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-199686 (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 11. Non-Power Processes I. 

Proceedings published on USB. 

Available from: 2022-09-26 Created: 2022-09-26 Last updated: 2023-03-07Bibliographically approved
Mejtoft, T., Lindahl, O., Öhberg, F., Pommer, L., Jonzén, K., Andersson, B. M., . . . Hallberg, P. (2022). Medtech innovation guide: an empiric model to support medical technology innovation. Health and Technology, 12(5), 911-922
Open this publication in new window or tab >>Medtech innovation guide: an empiric model to support medical technology innovation
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2022 (English)In: Health and Technology, ISSN 2190-7188, E-ISSN 2190-7196, Vol. 12, no 5, p. 911-922Article in journal (Refereed) Published
Abstract [en]

Innovation has become increasingly important for most industries to cope with rapid technological changes as well as changing societal needs. Even though there are many sectors with specific needs when it comes to supporting innovation, the medical technology sector is facing several unique challenges that both increases the lead-time from idea to finished product and decreases the number of innovations that are developed. This paper presents a proposed innovation guide that has been developed and evaluated as a support for the innovation process within medical technology research. The guide takes the unique characteristics of the medical technology sector into account and serves as a usable guide for the innovator. The complete guide contains both a structure for the process and a usable web application to support the journey from idea to finished products and services. The paper also includes a new readiness level, Sect. 4.2 to provide support both when developing and determining the readiness for clinical implementation of a medical technology innovation.

Place, publisher, year, edition, pages
Springer, 2022
Keywords
Biomedical engineering, Innovation, Medical technology, Medtech innovation guide
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:umu:diva-199115 (URN)10.1007/s12553-022-00689-0 (DOI)000842927600002 ()2-s2.0-85136569769 (Scopus ID)
Funder
Umeå UniversitySwedish Agency for Economic and Regional GrowthEuropean Regional Development Fund (ERDF)
Available from: 2022-10-05 Created: 2022-10-05 Last updated: 2022-10-05Bibliographically approved
Jonsson, U. G., Lindahl, O. A. & Andersson, B. M. (2020). Using a look-up table technique and finite element calculations for quick detection of stiff inclusions in silicone rubber. Engineering computations, 37(6), 2137-2153
Open this publication in new window or tab >>Using a look-up table technique and finite element calculations for quick detection of stiff inclusions in silicone rubber
2020 (English)In: Engineering computations, ISSN 0264-4401, E-ISSN 1758-7077, Vol. 37, no 6, p. 2137-2153Article in journal (Refereed) Published
Abstract [en]

Purpose: The aim of the study was to show that a new method, using a look-up table technique, can be used to detect the presence and position of an inclusion embedded in a tissue-like material. Due to the time-consuming nature of the finite element (FE) method or FEM, real-time applications involving FEM as part of a control loop, are traditionally limited to slowly varying systems. By using a simplified two-dimensional FE model and a look-up table, we show by simulations and experiments that it is possible to achieve reasonable computational times in a tactile resonance sensor application.

Design/methodology/approach: A piezoelectric disk was placed in the center of a silicone rubber disk (SRD) with viscoelastic properties, where it acted as both sensor and actuator and dissipated radial acoustic waves into the silicone. The look-up table was constructed by calculating the radial Lamb wave transition frequencies in the impedance frequency response of the sensor while varying the position of an inclusion. A position-matching algorithm was developed that matched measured and calculated Lamb wave transitions and thereby identified the presence and position of an inclusion.

Findings: In an experiment, the position of a hard inclusion was determined by measuring the Lamb transition frequencies of the first radial resonance in two SRDs. The result of the matching algorithm for Disk 1 was that the matched position was less than 3% from the expected value. For Disk 2, the matching algorithm erroneously reported two false positions before reporting a position that was less than 5% from the expected value. An explanation for this discrepancy is presented. In a verifying experiment, the algorithm identified the condition with no inclusion present.

Originality/value: The approach outlined in this work, adds to the prospect of developing time-sensitive diagnostic instruments. This approach has the potential to provide a powerful technique to quickly present spatial information on detected tumors.

Place, publisher, year, edition, pages
Emerald Group Publishing Limited, 2020
Keywords
Finite Element Method, Look-up table, Fractional derivative model, Lamb waves, Piezoelectric sensor, Silicone rubber
National Category
Computer Sciences Electrical Engineering, Electronic Engineering, Information Engineering Physical Sciences
Identifiers
urn:nbn:se:umu:diva-168955 (URN)10.1108/EC-02-2019-0036 (DOI)000512206600001 ()2-s2.0-85079439504 (Scopus ID)
Funder
European Commission
Available from: 2020-04-01 Created: 2020-04-01 Last updated: 2022-04-04Bibliographically approved
Mejtoft, T., Andersson, B. M., Pommer, L., Karolina, J., Kerstin, R., Wåhlin, A., . . . Hallberg, P. (2019). Kan en branschspecifik innovationsmodell öka ”success rate” för medicintekniska innovationer?. In: : . Paper presented at Medicinteknikdagarna 2019, Linköping, Sweden, 2-3 oktober, 2019.
Open this publication in new window or tab >>Kan en branschspecifik innovationsmodell öka ”success rate” för medicintekniska innovationer?
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2019 (Swedish)Conference paper, Oral presentation only (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-166751 (URN)
Conference
Medicinteknikdagarna 2019, Linköping, Sweden, 2-3 oktober, 2019
Available from: 2019-12-26 Created: 2019-12-26 Last updated: 2021-11-01Bibliographically approved
Shirdel, M., Bergdahl A., I., Andersson, B. M., Wingfors, H., Sommar, J. N. & Liljelind, I. E. (2019). Passive personal air sampling of dust in a working environment: A pilot study. Journal of Occupational and Environmental Hygiene, 16(10), 675-684
Open this publication in new window or tab >>Passive personal air sampling of dust in a working environment: A pilot study
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2019 (English)In: Journal of Occupational and Environmental Hygiene, ISSN 1545-9624, E-ISSN 1545-9632, Vol. 16, no 10, p. 675-684Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to make a preliminary evaluation of the University of North Carolina passive aerosol sampler (UNC sampler) for personal air sampling of particles. Nine personal air samplings of respirable fraction were conducted in an open-pit mine, with pairwise UNC samplers and a respirable cyclone mounted on the chest of workers. UNC samples were analyzed with scanning electron microscopy (SEM) and to some extent energy dispersive X-ray spectroscopy (EDS). Respirable cyclone filter samples were weighed. Correlations and particle elemental compositions were described. Microscopic imaging of the collection surface showed that the particles were heterogeneously deposited across the surface of the UNC sampler. Collected particles were shaped as gravel particles and the resulting particle size distribution in air showed a peak at ca. 3 µm aerodynamic diameter, similarly to what has previously been reported from the same mine. The elemental composition indicated mineral origin. All correlations between the airborne mass concentrations from UNC samplers and respirable cyclones (Pearson = 0.54 and Spearman = 0.43) and between pairs of parallel UNC samplers (Pearson = 0.55 and Spearman = 0.67) were weak. The UNC sampler mass concentrations were approximately 30 times higher than those measured with the respirable cyclone. In conclusion, the UNC sampler, when used for personal sampling in a mine, provides a reasonable particle size distribution and the deposited particles appeared to be of mineral origin and not from textile or skin but the approximately 30-fold overestimation of mass concentrations when comparing with respirable cyclone sampling indicates that further improvements are necessary. Positioning of the sampler may be critical and moving the UNC sampler from the chest to e.g. the top of a helmet might be an improvement. Grounding of the sampler in order to avoid static electricity might also be useful. The UNC sampler should continue to be researched for personal sampling, as passive sampling might become a useful alternative to more laborious sampling techniques.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2019
Keywords
Area factor, UNC passive aerosol sampler, mesh factor, mineral, occupational exposure, respirable cyclone
National Category
Public Health, Global Health, Social Medicine and Epidemiology Occupational Health and Environmental Health Physical Sciences
Identifiers
urn:nbn:se:umu:diva-162647 (URN)10.1080/15459624.2019.1648814 (DOI)000490322700001 ()31442106 (PubMedID)2-s2.0-85071328531 (Scopus ID)
Funder
Forte, Swedish Research Council for Health, Working Life and Welfare, 2012-0478
Available from: 2019-08-26 Created: 2019-08-26 Last updated: 2023-03-23Bibliographically approved
Shirdel, M., Sommar, J. N., Andersson, B. M., Bergdahl, I. A., Wingfors, H. & Liljelind, I. E. (2018). Choosing the number of images and image position when analysing the UNC Passive Aerosol Sampler for occupational exposure assessment. Journal of Occupational and Environmental Hygiene, 15(11), 767-772
Open this publication in new window or tab >>Choosing the number of images and image position when analysing the UNC Passive Aerosol Sampler for occupational exposure assessment
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2018 (English)In: Journal of Occupational and Environmental Hygiene, ISSN 1545-9624, E-ISSN 1545-9632, Vol. 15, no 11, p. 767-772Article in journal (Refereed) Published
Abstract [en]

The University of North Carolina passive aerosol sampler (UNC sampler) could be an alternative when measuring occupational dust exposure, but the time required for microscopic imaging of the sampler needs to be reduced to make it more attractive. The aims of this study were to 1) characterise the effect on precision when reducing imaging, in order to shorten analysis time and 2) assess if the position of the images makes a difference. Eighty-eight samplers were deployed in different locations of an open pit mine. Sixty images were captured for each UNC sampler, covering 51% of its collection surface, using scanning electron microscopy. Bootstrapped samples were generated with different image combinations, to assess the within-sampler coefficient of variation (CVws) for different numbers of images. In addition, the particle concentration relative to the distance from the centre of the sampler was studied. Reducing the number of images collected from the UNC sampler led to up to 8.3% CVws for ten images when calculating respirable fraction. As the overall CV has previously been assessed to 36%, the additional contribution becomes minimal, increasing the overall CV to 37%. The mean concentrations of the images were modestly related to distance from the centre of the sampler. The CVws changed from 8.26% to 8.13% for ten images when applying rules for the image collection based on distance. Thus, the benefit of these rules on the precision is small and the images can therefore be chosen at random. In conclusion, reducing the number of images analysed from 60 to 10, corresponding to a reduction of the imaged sampling area from 51% to 8.5%, results in a negligible loss in precision for respirable fraction dust measurements in occupational environments.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
Keywords
Dust particles, PM10, PM2.5, occupational hygienist, passive sampling, respirable fraction
National Category
Public Health, Global Health, Social Medicine and Epidemiology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-152114 (URN)10.1080/15459624.2018.1508875 (DOI)000451621900002 ()30111275 (PubMedID)2-s2.0-85057555816 (Scopus ID)
Available from: 2018-09-27 Created: 2018-09-27 Last updated: 2023-03-23Bibliographically approved
Shirdel, M., Andersson, B. M., Bergdahl, I., Sommar, J. N., Wingfors, H. & Liljelind, I. E. (2018). Improving the UNC passive aerosol sampler model based on comparison with commonly used aerosol sampling methods. Annals of Work Exposures and Health, 62(3), 328-338
Open this publication in new window or tab >>Improving the UNC passive aerosol sampler model based on comparison with commonly used aerosol sampling methods
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2018 (English)In: Annals of Work Exposures and Health, ISSN 2398-7308 , E-ISSN 2398-7316 , Vol. 62, no 3, p. 328-338Article in journal (Refereed) Published
Abstract [en]

Objectives: In an occupational environment, passive sampling could be an alternative to active sampling with pumps for sampling of dust. One passive sampler is the University of North Carolina passive aerosol sampler (UNC sampler). It is often analysed by microscopic imaging. Promising results have been shown for particles above 2.5 µm, but indicate large underestimations for PM2.5. The aim of this study was to evaluate, and possibly improve, the UNC sampler for stationary sampling in a working environment.

Methods: Sampling was carried out at 8-h intervals during 24 h in four locations in an open pit mine with UNC samplers, respirable cyclones, PM10 and PM2.5 impactors, and an aerodynamic particle sizer (APS). The wind was minimal. For quantification, two modifications of the UNC sampler analysis model, UNC sampler with hybrid model and UNC sampler with area factor, were compared with the original one, UNC sampler with mesh factor derived from wind tunnel experiments. The effect of increased resolution for the microscopic imaging was examined.

Results: Use of the area factor and a higher resolution eliminated the underestimation for PM10 and PM2.5. The model with area factor had the overall lowest deviation versus the impactor and the cyclone. The intraclass correlation (ICC) showed that the UNC sampler had a higher precision and better ability to distinguish between different exposure levels compared to the cyclone (ICC: 0.51 versus 0.24), but lower precision compared to the impactor (PM10: 0.79 versus 0.99; PM2.5: 0.30 versus 0.45). The particle size distributions as calculated from the different UNC sampler analysis models were visually compared with the distributions determined by APS. The distributions were obviously different when the UNC sampler with mesh factor was used but came to a reasonable agreement when the area factor was used.

Conclusions: High resolution combined with a factor based on area only, results in no underestimation of small particles compared to impactors and cyclones and a better agreement with the APS’s particle size distributions. The UNC sampler had lower precision than the impactors, but higher than the respirable cyclone. The UNC sampler with area factor could be used for PM2.5, PM10 and respirable fraction measurements in this working environment without wind.

Place, publisher, year, edition, pages
Oxford University Press, 2018
Keywords
inorganic dust, mesh factor, PM10, PM2.5, respirable fraction, UNC passive aerosol sampler, working environment
National Category
Occupational Health and Environmental Health Physical Sciences
Identifiers
urn:nbn:se:umu:diva-145698 (URN)10.1093/annweh/wxx110 (DOI)000432804600008 ()29300818 (PubMedID)2-s2.0-85050719053 (Scopus ID)
Available from: 2018-03-14 Created: 2018-03-14 Last updated: 2024-07-02Bibliographically approved
Shirdel, M., Wingfors, H., Andersson, B. M., Sommar, J. N., Bergdahl, I. A. & Liljelind, I. E. (2017). A pilot study: the UNC passive aerosol sampler in a working environment. Annals of Work Exposures and Health, 61(8), 1029-1034
Open this publication in new window or tab >>A pilot study: the UNC passive aerosol sampler in a working environment
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2017 (English)In: Annals of Work Exposures and Health, ISSN 2398-7308 , E-ISSN 2398-7316 , Vol. 61, no 8, p. 1029-1034Article in journal (Refereed) Published
Abstract [en]

Objectives: Dust is generally sampled on a filter using air pumps, but passive sampling could be a cost-effective alternative. One promising passive sampler is the University of North Carolina passive aerosol sampler (UNC sampler). The aim of this study is to characterize and compare the UNC sampler’s performance with PM10 and PM2.5 impactors in a working environment.

Methods: Area sampling was carried out at different mining locations using UNC samplers in parallel with PM2.5 and PM10 impactors. Two different collection surfaces, polycarbonate (PC) and carbon tabs (CT), were employed for the UNC sampling. Sampling was carried out for 4–25 hours.

Results: The UNC samplers underestimated the concentrations compared to PM10 and PM2.5 impactor data. At the location with the highest aerosol concentration, the time-averaged mean of PC showed 24% and CT 35% of the impactor result for PM2.5. For PM10, it was 39% with PC and 58% with CT. Sample blank values differed between PC and CT. For PM2.5, PC blank values were ~7 times higher than those of CT, but only 1.8 times higher for PM10. The blank variations were larger for PC than for CT.

Conclusions: Particle mass concentrations appear to be underestimated by the UNC sampler compared to impactors, more so for PM2.5 than for PM10. CT may be preferred as a collection surface because the blank values were lower and less variable than for PC. Future validations in the working environment should include respirable dust sampling.

Place, publisher, year, edition, pages
Oxford University Press, 2017
Keywords
inorganic dust, PM2.5, PM10, scanning electron microscopy, UNC passive aerosol sampler, working environment
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:umu:diva-140539 (URN)10.1093/annweh/wxx067 (DOI)000417608500013 ()29028256 (PubMedID)2-s2.0-85050743710 (Scopus ID)
Available from: 2017-10-13 Created: 2017-10-13 Last updated: 2024-07-02Bibliographically approved
Projects
Instrument and method for future diagnostics in pathology [2017-01399_Vinnova]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2440-9543

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