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Ghorbani, R. & Schmidt, F. M. (2019). Fitting of single-exhalation profiles using a pulmonary gas exchange model: application to carbon monoxide. Journal of Breath Research, 13(2), Article ID 026001.
Open this publication in new window or tab >>Fitting of single-exhalation profiles using a pulmonary gas exchange model: application to carbon monoxide
2019 (English)In: Journal of Breath Research, ISSN 1752-7155, E-ISSN 1752-7163, Vol. 13, no 2, article id 026001Article in journal (Refereed) Published
Abstract [en]

Real-time breath gas analysis coupled to gas exchange modeling is emerging as promising strategy to enhance the information gained from breath tests. It is shown for exhaled breath carbon monoxide (eCO), a potential biomarker for oxidative stress and respiratory diseases, that a weighted, nonlinear least-squares fit of simulated to measured expirograms can be used to extract physiological parameters, such as airway and alveolar concentrations and diffusing capacities. Experimental CO exhalation profiles are acquired with high time-resolution and precision using mid-infrared tunable diode laser absorption spectroscopy and online breath sampling. A trumpet model with axial diffusion is employed to generate eCO profiles based on measured exhalation flow rates and volumes. The concept is demonstrated on two healthy non-smokers exhaling at a flow rate of 250 ml s−1 during normal breathing and at 120 ml s−1 after 10 s of breath-holding. The obtained gas exchange parameters of the two subjects are in a similar range, but clearly distinguishable. Over a series of twenty consecutive expirograms, the intra-individual variation in the alveolar parameters is less than 6%. After a 2 h exposure to 10 ± 2 ppm CO, end-tidal and alveolar CO concentrations are significantly increased (by factors of 2.7 and 4.9 for the two subjects) and the airway CO concentration is slightly higher, while the alveolar diffusing capacity is unchanged compared to before exposure. Using model simulations, it is found that a three-fold increase in maximum airway CO flux and a reduction in alveolar diffusing capacity by 60% lead to clearly distinguishable changes in the exhalation profile shape. This suggests that extended breath CO analysis has clinical relevance in assessing airway inflammation and chronic obstructive pulmonary disease. Moreover, the novel methodology contributes to the standardization of real-time breath gas analysis.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2019
Keywords
real-time breath gas analysis, carbon monoxide (CO), pulmonary gas exchange model, single-exhalation profile, laser absorption spectroscopy
National Category
Physiology Bioinformatics (Computational Biology) Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-152093 (URN)10.1088/1752-7163/aafc91 (DOI)000460174200001 ()30620936 (PubMedID)
Note

Originally included in thesis in manuscript form 

Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2019-03-27Bibliographically approved
Zhao, G., Hausmaninger, T., Schmidt, F. M., Ma, W. & Axner, O. (2019). High-resolution trace gas detection by sub-Doppler noise-immune cavity-enhanced optical heterodyne molecular spectrometry: application to detection of acetylene in human breath. Optics Express, 27(13), 17940-17953
Open this publication in new window or tab >>High-resolution trace gas detection by sub-Doppler noise-immune cavity-enhanced optical heterodyne molecular spectrometry: application to detection of acetylene in human breath
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2019 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 27, no 13, p. 17940-17953Article in journal (Refereed) Published
Abstract [en]

A sensitive high-resolution sub-Doppler detecting spectrometer, based on noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS), for trace gas detection of species whose transitions have severe spectral overlap with abundant concomitant species is presented. It is designed around a NICE-OHMS instrumentation utilizing balanced detection that provides shot-noise limited Doppler-broadened (Db) detection. By synchronous dithering the positions of the two cavity mirrors, the effect of residual etalons between the cavity and other surfaces in the system could be reduced. An Allan deviation of the absorption coefficient of 2.2 × 10-13 cm-1 at 60 s, which, for the targeted transition in C2H2, corresponds to a 3σ detection sensitivity of 130 ppt, is demonstrated. It is shown that despite significant spectral interference from CO2 at the targeted transition, which precludes Db detection of C2H2, acetylene could be detected in exhaled breath of healthy smokers.

Place, publisher, year, edition, pages
Optical Society of America, 2019
National Category
Atom and Molecular Physics and Optics Physical Chemistry Medical Engineering
Identifiers
urn:nbn:se:umu:diva-161422 (URN)10.1364/OE.27.017940 (DOI)000472621000043 ()31252745 (PubMedID)
Funder
Swedish Research Council, 2015-04374Swedish Research Council, 2013-6031The Kempe Foundations, JCK-1317The Kempe Foundations, SMK-1446
Available from: 2019-07-07 Created: 2019-07-07 Last updated: 2019-07-25Bibliographically approved
Lu, C., Vieira, F. S., Schmidt, F. M. & Foltynowicz, A. (2019). Near-Infrared Continuous-Filtering Vernier Spectroscopy in a Flame. In: Conference on Lasers and Electro-Optics: . Paper presented at Conference on Lasers and Electro-Optics (CLEO), San Jose, California, United States, 5-10 May, 2019. IEEE, Article ID SM2N.5.
Open this publication in new window or tab >>Near-Infrared Continuous-Filtering Vernier Spectroscopy in a Flame
2019 (English)In: Conference on Lasers and Electro-Optics, IEEE, 2019, article id SM2N.5Conference paper, Published paper (Refereed)
Abstract [en]

A continuous-filtering Vernier spectrometer based on an Er:fiber femtosecond laser was developed to acquire broadband H2O and OH spectra in a premixed CH4/air flame with 25 ms time resolution and percent precision on concentrations retrieval.

Place, publisher, year, edition, pages
IEEE, 2019
Series
Conference on Lasers and Electro-Optics, ISSN 2160-9020
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-163709 (URN)10.1364/CLEO_SI.2019.SM2N.5 (DOI)000482226301121 ()2-s2.0-85068128969 (Scopus ID)978-1-943580-57-6 (ISBN)
Conference
Conference on Lasers and Electro-Optics (CLEO), San Jose, California, United States, 5-10 May, 2019
Available from: 2019-10-16 Created: 2019-10-16 Last updated: 2019-10-16Bibliographically approved
Lu, C., Vieira, F. S., Schmidt, F. M. & Foltynowicz, A. (2019). Time-resolved continuous-filtering Vernier spectroscopy of H2O and OH radical in a flame. Optics Express, 27(21), 29521-29533
Open this publication in new window or tab >>Time-resolved continuous-filtering Vernier spectroscopy of H2O and OH radical in a flame
2019 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 27, no 21, p. 29521-29533Article in journal (Refereed) Published
Abstract [en]

We use broadband near-infrared continuous-filtering Vernier spectroscopy (CF-VS) for time-resolved detection of H2O and OH radical in a premixed CH4/air flat flame. The CF-VS spectrometer is based on a femtosecond Er:fiber laser, an external cavity that contains the flame, and a detection system comprising a rotating diffraction grating and photodetectors. Spectra of H2O and OH radical around 1570 nm are continuously recorded with 6.6 GHz spectral resolution, 4.0 x 10-7 cm-1 absorption sensitivity, and 25 ms time resolution, while the fuel-air equivalence ratio is periodically modulated with a square wave. The concentrations of the two analytes are retrieved with percent level precision by a fit of a Vernier model to each spectrum spanning 13 nm. The temporal profiles of both concentrations in each modulation cycle are repeatable and the steady-state concentration levels are in good agreement with predictions based on one-dimensional simulations of a static flat flame. The robust CF-VS spectrometer opens up for quantitative monitoring of multiple products of time-varying combustion processes with relatively simple data acquisition procedures.

Place, publisher, year, edition, pages
Optical Society of America, 2019
Keywords
Acoustooptic modulators, Cavity ring down spectroscopy, Coupling efficiency, Diffraction gratings, Fourier transform spectroscopy, Polarization maintaining fibers
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-164253 (URN)10.1364/OE.27.029521 (DOI)000489954500006 ()31684212 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, KAW 2015.0159
Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2019-11-11Bibliographically approved
Rutkowski, L., Foltynowicz, A., Schmidt, F. M., Johansson, A. C., Khodabakhsh, A., Kyuberis, A. A., . . . Tennyson, J. (2018). An experimental water line list at 1950 K in the 6250–6670 cm−1 region. Journal of Quantitative Spectroscopy and Radiative Transfer, 205, 213-219
Open this publication in new window or tab >>An experimental water line list at 1950 K in the 6250–6670 cm−1 region
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2018 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 205, p. 213-219Article in journal (Refereed) Published
Abstract [en]

An absorption spectrum of (H2O)-O-16 at 1950 K is recorded in a premixed methane/air flat flame using a cavity-enhanced optical frequency comb-based Fourier transform spectrometer. 2417 absorption lines are identified in the 6250-6670 cm(-1) region with an accuracy of about 0.01 cm(-1). Absolute line intensities are retrieved using temperature and concentration values obtained by tunable diode laser absorption spectroscopy. Line assignments are made using a combination of empirically known energy levels and predictions from the new POKAZATEL variational line list. 2030 of the observed lines are assigned to 2937 transitions, once blends are taken into account. 126 new energy levels of (H2O)-O-16 are identified. The assigned transitions belong to 136 bands and span rotational states up to J = 27.

Keywords
Water, Absorption, Fourier transform spectroscopy, Optical cavity, Frequency comb, Calculations
National Category
Atom and Molecular Physics and Optics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:umu:diva-141519 (URN)10.1016/j.jqsrt.2017.10.016 (DOI)000417665000023 ()
Available from: 2017-11-06 Created: 2017-11-06 Last updated: 2018-06-09Bibliographically approved
Qu, Z., Holmgren, P., Skoglund, N., Wagner, D. R., Broström, M. & Schmidt, F. M. (2018). Distribution of temperature, H2O and atomic potassium during entrained flow biomass combustion: coupling in situ TDLAS with modeling approaches and ash chemistry. Combustion and Flame, 188, 488-497
Open this publication in new window or tab >>Distribution of temperature, H2O and atomic potassium during entrained flow biomass combustion: coupling in situ TDLAS with modeling approaches and ash chemistry
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2018 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 188, p. 488-497Article in journal (Refereed) Published
Abstract [en]

Tunable diode laser absorption spectroscopy (TDLAS) is employed for simultaneous detection of gas temperature, water vapor (H2O) and gas-phase atomic potassium, K(g), in an atmospheric, research-scale entrained flow reactor (EFR). In situ measurements are conducted at four different locations in the EFR core to study the progress of thermochemical conversion of softwood and Miscanthus powders with focus on the primary potassium reactions. In an initial validation step during propane flame operation, the measured axial EFR profiles of H2O density-weighted, path-averaged temperature, path-averaged H2O concentration and H2O column density are found in good agreement with 2D CFD simulations and standard flue gas analysis. During biomass conversion, temperature and H2O are significantly higher than for the propane flame, up to 1500 K and 9%, respectively, and K(g) concentrations between 0.2 and 270 ppbv are observed. Despite the large difference in initial potassium content between the fuels, the K(g) concentrations obtained at each EFR location are comparable, which highlights the importance of considering all major ash-forming elements in the fuel matrix. For both fuels, temperature and K(g) decrease with residence time, and in the lower part of the EFR, K(g) is in excellent agreement with thermodynamic equilibrium calculations evaluated at the TDLAS-measured temperatures and H2O concentrations. However, in the upper part of the EFR, where the measured H2O suggested a global equivalence ratio smaller than unity, K(g) is far below the predicted equilibrium values. This indicates that, in contrast to the organic compounds, potassium species rapidly undergo primary ash transformation reactions even if the fuel particles reside in an oxygen-deficient environment.

Place, publisher, year, edition, pages
New York: Elsevier, 2018
Keywords
Tunable diode laser absorption spectroscopy (TDLAS), Atomic potassium, Entrained flow reactor, Biomass combustion, Thermodynamic equilibrium calculations, Computational fluid dynamics (CFD)
National Category
Atom and Molecular Physics and Optics Chemical Process Engineering Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-141456 (URN)10.1016/j.combustflame.2017.10.013 (DOI)000424859100040 ()
Projects
Bio4Energy
Available from: 2017-11-06 Created: 2017-11-06 Last updated: 2019-09-02Bibliographically approved
Henderson, B., Khodabakhsh, A., Metsälä, M., Ventrillard, I., Schmidt, F. M., Romanini, D., . . . Cristescu, S. M. (2018). Laser spectroscopy for breath analysis: towards clinical implementation. Applied physics. B, Lasers and optics (Print), 124(8), Article ID 161.
Open this publication in new window or tab >>Laser spectroscopy for breath analysis: towards clinical implementation
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2018 (English)In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 124, no 8, article id 161Article in journal (Refereed) Published
Abstract [en]

Detection and analysis of volatile compounds in exhaled breath represents an attractive tool for monitoring the metabolic status of a patient and disease diagnosis, since it is non-invasive and fast. Numerous studies have already demonstrated the benefit of breath analysis in clinical settings/applications and encouraged multidisciplinary research to reveal new insights regarding the origins, pathways, and pathophysiological roles of breath components. Many breath analysis methods are currently available to help explore these directions, ranging from mass spectrometry to laser-based spectroscopy and sensor arrays. This review presents an update of the current status of optical methods, using near and mid-infrared sources, for clinical breath gas analysis over the last decade and describes recent technological developments and their applications. The review includes: tunable diode laser absorption spectroscopy, cavity ring-down spectroscopy, integrated cavity output spectroscopy, cavity-enhanced absorption spectroscopy, photoacoustic spectroscopy, quartz-enhanced photoacoustic spectroscopy, and optical frequency comb spectroscopy. A SWOT analysis (strengths, weaknesses, opportunities, and threats) is presented that describes the laser-based techniques within the clinical framework of breath research and their appealing features for clinical use.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2018
National Category
Atom and Molecular Physics and Optics Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:umu:diva-150269 (URN)10.1007/s00340-018-7030-x (DOI)000440163700001 ()2-s2.0-85050942138 (Scopus ID)
Available from: 2018-07-31 Created: 2018-07-31 Last updated: 2018-11-01Bibliographically approved
Ghorbani, R., Blomberg, A. & Schmidt, F. M. (2018). Modeling pulmonary gas exchange and single-exhalation profiles of carbon monoxide. Frontiers in Physiology, 9, Article ID 927.
Open this publication in new window or tab >>Modeling pulmonary gas exchange and single-exhalation profiles of carbon monoxide
2018 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, article id 927Article in journal (Refereed) Published
Abstract [en]

Exhaled breath carbon monoxide (eCO) is a candidate biomarker for non-invasive assessment of oxidative stress and respiratory diseases. Standard end-tidal CO analysis, however, cannot distinguish, whether eCO reflects endogenous CO production, lung diffusion properties or exogenous sources, and is unable to resolve a potential airway contribution. Coupling real-time breath gas analysis to pulmonary gas exchange modeling holds promise to improve the diagnostic value of eCO. A trumpet model with axial diffusion (TMAD) is used to simulate the dynamics of CO gas exchange in the respiratory system and corresponding eCO concentrations for the first time. The mass balance equation is numerically solved employing a computationally inexpensive routine implementing the method of lines, which provides the distribution of CO in the respiratory tract during inhalation, breath-holding and exhalation with 1 mm spatial and 0.01 s temporal resolution. Initial estimates of the main TMAD parameters, the maximum CO fluxes and diffusing capacities in alveoli and airways, are obtained using healthy population tissue, blood and anatomical data. To verify the model, mouth-exhaled expirograms from two healthy subjects, measured with a novel, home-built laser-based CO sensor, are compared to single-exhalation profiles simulated using actual breath sampling data, such as exhalation flow rate (EFR) and volume. A very good agreement is obtained in exhalation phases I and III for EFRs between 55 and 220 ml/s and after 10 s and 20 s of breath-holding, yielding a unique set of TMAD parameters. The results confirm the recently observed EFR dependence of CO expirograms and suggest that measured end-tidal eCO is always lower than alveolar and capillary CO. Breath-holding allows the observation of close-to-alveolar CO concentrations and increases the sensitivity to the airway TMAD parameters in exhalation phase I. A parametric simulation study shows that a small increase in airway flux can be distinguished from an increase in alveolar flux, and that slight changes in alveolar flux and diffusing capacity have a significantly different effect on phase III of the eCO profiles.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2018
Keywords
carbon monoxide (CO), pulmonary gas exchange, computational modeling, real-time breath gas analysis, single-exhalation profile, laser absorption spectroscopy
National Category
Physiology Bioinformatics (Computational Biology) Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-150270 (URN)10.3389/fphys.2018.00927 (DOI)000440204000001 ()
Available from: 2018-07-31 Created: 2018-07-31 Last updated: 2018-11-01Bibliographically approved
Boman, C., Öhman, M., Broström, M., Skoglund, N., Schmidt, F. M., Backman, R. & Boström, D. (2017). Ash transformation chemistry in biomass fixed beds with focus on slagging and aerosols: 20 years of research and new developments. Paper presented at 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC. Abstract of Papers of the American Chemical Society, 254
Open this publication in new window or tab >>Ash transformation chemistry in biomass fixed beds with focus on slagging and aerosols: 20 years of research and new developments
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2017 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal, Meeting abstract (Other academic) Published
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-148191 (URN)
Conference
254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC
Note

Meeting Abstract: 24

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-06-09
Ögren, Y., Sepman, A., Qu, Z., Schmidt, F. M. & Wiinikka, H. (2017). Comparison of measurement techniques for temperature and soot concentration in premixed, small-scale burner flames. Energy & Fuels, 31(10), 11328-11336
Open this publication in new window or tab >>Comparison of measurement techniques for temperature and soot concentration in premixed, small-scale burner flames
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2017 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 10, p. 11328-11336Article in journal (Refereed) Published
Abstract [en]

Optical and intrusive measurement techniques for temperature and soot concentration in hot reacting flows were tested on a small-scale burner in fuel-rich, oxygen-enriched atmospheric flat flames produced to simulate the environment inside an entrained flow reactor. The optical techniques comprised two-color pyrometry (2C-PYR), laser extinction (LE), and tunable diode laser absorption spectroscopy (TDLAS), and the intrusive methods included fine-wire thermocouple thermometry (TC) and electrical low pressure impactor (ELPI) particle analysis. Vertical profiles of temperature and soot concentration were recorded in flames with different equivalence and O2/N2 ratios. The 2C-PYR and LE data were derived assuming mature soot. Gas temperatures up to 2200 K and soot concentrations up to 3 ppmv were measured. Close to the burner surface, the temperatures obtained with the pyrometer were up to 300 K higher than those measured by TDLAS. Further away from the burner, the difference was within 100 K. The TC-derived temperatures were within 100 K from the TDLAS results for most of the flames. At high signal-to-noise ratio and in flame regions with mature soot, the temperatures measured by 2C-PYR and TDLAS were similar. The soot concentrations determined with 2C-PYR were close to those obtained with LE but lower than the ELPI results. It is concluded that the three optical techniques have good potential for process control applications in combustion and gasification processes. 2C-PYR offers simpler installation and 2D imaging, whereas TDLAS and LE provide better accuracy and dynamic range without calibration procedures.

Place, publisher, year, edition, pages
Washington: American Chemical Society (ACS), 2017
Keywords
flow coal gasifier, volume fraction, wavelength dependence, optical diagnostics, refractive index, gas temperature, pyrometry, biomass, size, extinction
National Category
Atom and Molecular Physics and Optics Energy Systems Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-141034 (URN)10.1021/acs.energyfuels.7b01168 (DOI)000413710300104 ()
Available from: 2017-10-22 Created: 2017-10-22 Last updated: 2018-06-09Bibliographically 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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5065-7786

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