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Publications (10 of 88) Show all publications
Eriksson, R., Gren, P., Sjödahl, M. & Ramser, K. (2022). 3D spatial control and the spatial generation of stimulated Raman scattering in ethanol. In: : . Paper presented at ECONOS European Conference on Non-linear Optical Spectroscopy, September 25-28, 2022, Kiruna, Sweden.
Open this publication in new window or tab >>3D spatial control and the spatial generation of stimulated Raman scattering in ethanol
2022 (English)Conference paper, Oral presentation only (Other academic)
Keywords
Stimulated Raman scattering
National Category
Atom and Molecular Physics and Optics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-97135 (URN)
Conference
ECONOS European Conference on Non-linear Optical Spectroscopy, September 25-28, 2022, Kiruna, Sweden
Available from: 2023-05-12 Created: 2023-05-12 Last updated: 2023-09-05Bibliographically approved
Dembele, V., Wahl, J., Sjödahl, M. & Ramser, K. (2022). Correlation properties of a spatially quasi-incoherent imaging interferometer. Applied Optics, 61(19), 5806-5812
Open this publication in new window or tab >>Correlation properties of a spatially quasi-incoherent imaging interferometer
2022 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 61, no 19, p. 5806-5812Article in journal (Refereed) Published
Abstract [en]

The depth-gating capacity of a spatially quasi-incoherent imaging interferometer is investigated in relation to the 3D correlation properties of diffraction field laser speckles. The system exploits a phase-stepped imaging Michelson-type interferometer in which spatially quasi-incoherent illumination is generated by passing an unexpanded laser beam through a rotating diffuser. Numerical simulations and optical experiments both verify that the depth-gating capacity of the imaging interferometer scales as 𝜆/2NA2𝑝λ/2NAp2, where 𝜆λ is the wavelength of the laser and NA𝑝NAp is the numerical aperture of the illumination. For a set depth gate of 150 µm, the depth-gating capacity of the interferometer is demonstrated by scanning a standard USAF target through the measurement volume. The results obtained show that an imaging tool of this kind is expected to provide useful capabilities for imaging through disturbing media and where a single wavelength is required.

Place, publisher, year, edition, pages
Optical Society of America, 2022
National Category
Atom and Molecular Physics and Optics Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-92225 (URN)10.1364/AO.459241 (DOI)000822017300038 ()36255816 (PubMedID)2-s2.0-85133659511 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-07-22 (sofila)

Available from: 2022-07-22 Created: 2022-07-22 Last updated: 2023-10-11Bibliographically approved
Dembele, V., Wahl, J., Sjödahl, M. & Ramser, K. (2022). Depth-resolved interferometric imaging utilizing a spatially quasi-incoherent light source. In: Proceedings Digital Holography and 3-D Imaging 2022: . Paper presented at Digital Holography and Three-Dimensional Imaging Topical Meeting, Cambridge, United Kingdom, August 1-4, 2022. Optica Publishing Group, Article ID W7A.1.
Open this publication in new window or tab >>Depth-resolved interferometric imaging utilizing a spatially quasi-incoherent light source
2022 (English)In: Proceedings Digital Holography and 3-D Imaging 2022, Optica Publishing Group , 2022, article id W7A.1Conference paper, Published paper (Refereed)
Abstract [en]

An interferometric technique that utilize a spatially quasi-incoherent light source to perform interferometric measurements involving diffusely scattering objects is presented. The proposed technique is demonstrated with settings that give a depth gate of 90 µm.

Place, publisher, year, edition, pages
Optica Publishing Group, 2022
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-94793 (URN)2-s2.0-85141463701 (Scopus ID)
Conference
Digital Holography and Three-Dimensional Imaging Topical Meeting, Cambridge, United Kingdom, August 1-4, 2022
Funder
The Kempe Foundations
Note

ISBN for host publication: 978-1-957171-12-8

Available from: 2022-12-12 Created: 2022-12-12 Last updated: 2023-09-05Bibliographically approved
Giordano, L., Nolte, A., Wittig, I., Pak, O., Knoepp, F., Ramser, K., . . . Sommer, N. (2022). Essential Role of Mitochondrial Cytochrome c Oxidase Subunit 4 Isoform 2 (Cox4i2) for Acute Pulmonary Oxygen Sensing. Paper presented at 21st European Bioenergetics Conference (EBEC2022), Aix-en-Provence, France, August 20-25, 2022. Biochimica et Biophysica Acta - Bioenergetics, 1863(Supplement), Article ID 148893.
Open this publication in new window or tab >>Essential Role of Mitochondrial Cytochrome c Oxidase Subunit 4 Isoform 2 (Cox4i2) for Acute Pulmonary Oxygen Sensing
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2022 (English)In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1863, no Supplement, article id 148893Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

Mitochondrial Cytochrome c Oxidase Subunit 4 Isoform 2 (Cox4i2) is essential for acute oxygen sensing and signaling in pulmonary arterial smooth muscle cells (PASMCs) by triggering the production of superoxide during acute hypoxia [1]. However, the molecular mechanism underlying Cox4i2-dependent oxygen sensing remains elusive. We analysed oxygen-dependent respiration by high resolution respirometry, redox changes of the electron transport chain (ETC) by RAMAN spectroscopy, and supercomplex formation by blue native gel analysis of PASMCs isolated from wild type (WT) and Cox4i2-/- mice. To understand the role of Cox4i2-specific cysteine residues we determined hypoxia-induced superoxide production and oxygen affinity in a mouse epithelial cell line (CMT167 cells) overexpressing either Cox4i1, or WT Cox4i2, or Cox4i2 mutants (C41S, C55A, C109S). Respiration and supercomplex formation were similar in WT and Cox4i2-/- PASMCs. Interestingly, hypoxia-induced reduction of ETC components (NADH, ubiquinol, and reduced cytochrome c) was prevented in Cox4i2-/- PASMCs. CMT167 cells expressing either Cox4i1, or Cox4i2 mutants lacked hypoxia-induced superoxide release, which was detected only in cells expressing WT Cox4i2. In contrast, overexpression of Cox4i1, or Cox4i2, or Cox4i2 mutants did not affect oxygen affinity. Our findings suggest that Cox4i2 does not alter superoxide production by rearrangement of supercomplexes, whereas its specific cysteines are needed for the superoxide release. In conclusion, Cox4i2 plays a major role in the hypoxia-induced reduction of ETC components, likely mediated through its redox-active cysteine residues.

Place, publisher, year, edition, pages
Elsevier, 2022
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-93350 (URN)10.1016/j.bbabio.2022.148893 (DOI)000854179100296 ()
Conference
21st European Bioenergetics Conference (EBEC2022), Aix-en-Provence, France, August 20-25, 2022
Note

Godkänd;2022;Nivå 0;2022-10-05 (hanlid);Konferensartikel i tidskrift;

Funder: DFG, German Research Foundation (268555672 – SFB 1213)

Part of special issue: EBEC2022, the 21st European Bioenergetics Conference, Aix-en-Provence, France, August 20-25, 2022, Abstract Book

Available from: 2022-10-05 Created: 2022-10-05 Last updated: 2023-09-05Bibliographically approved
Wahl, J., Klint, E., Hallbeck, M., Hillman, J., Wårdell, K. & Ramser, K. (2022). Impact of preprocessing methods on the Raman spectra of brain tissue. Biomedical Optics Express, 13(12), 6763-6777
Open this publication in new window or tab >>Impact of preprocessing methods on the Raman spectra of brain tissue
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2022 (English)In: Biomedical Optics Express, E-ISSN 2156-7085, Vol. 13, no 12, p. 6763-6777Article in journal (Refereed) Published
Abstract [en]

Delineating cancer tissue while leaving functional tissue intact is crucial in brain tumor resection. Despite several available aids, surgeons are limited by preoperative or subjective tools. Raman spectroscopy is a label-free optical technique with promising indications for tumor tissue identification. To allow direct comparisons between measurements preprocessing of the Raman signal is required. There are many recognized methods for preprocessing Raman spectra; however, there is no universal standard. In this paper, six different preprocessing methods were tested on Raman spectra (n > 900) from fresh brain tissue samples (n = 34). The sample cohort included both primary brain tumors, such as adult-type diffuse gliomas and meningiomas, as well as metastases of breast cancer. Each tissue sample was classified according to the CNS WHO 2021 guidelines. The six methods include both direct and iterative polynomial fitting, mathematical morphology, signal derivative, commercial software, and a neural network. Data exploration was performed using principal component analysis, t-distributed stochastic neighbor embedding, and k-means clustering. For each of the six methods, the parameter combination that explained the most variance in the data, i.e., resulting in the highest Gap-statistic, was chosen and compared to the other five methods. Depending on the preprocessing method, the resulting clusters varied in number, size, and associated spectral features. The detected features were associated with hemoglobin, neuroglobin, carotenoid, water, and protoporphyrin, as well as proteins and lipids. However, the spectral features seen in the Raman spectra could not be unambiguously assigned to tissue labels, regardless of preprocessing method. We have illustrated that depending on the chosen preprocessing method, the spectral appearance of Raman features from brain tumor tissue can change. Therefore, we argue both for caution in comparing spectral features from different Raman studies, as well as the importance of transparency of methodology and implementation of the preprocessing. As discussed in this study, Raman spectroscopy for in vivo guidance in neurosurgery requires fast and adaptive preprocessing. On this basis, a pre-trained neural network appears to be a promising approach for the operating room.

Place, publisher, year, edition, pages
Optica Publishing Group (formerly OSA), 2022
National Category
Medical Laboratory and Measurements Technologies
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-95007 (URN)10.1364/BOE.476507 (DOI)000917262200042 ()36589553 (PubMedID)2-s2.0-85143154815 (Scopus ID)
Funder
Swedish Foundation for Strategic Research, RMX18-0056
Note

Validerad;2023;Nivå 2;2023-02-17 (hanlid)

Available from: 2022-12-27 Created: 2022-12-27 Last updated: 2023-09-05Bibliographically approved
Eriksson, R., Gren, P., Sjödahl, M. & Ramser, K. (2022). Investigation of the Spatial Generation of Stimulated Raman Scattering Using Computer Simulation and Experimentation. Applied Spectroscopy, 26(11), 1307-1316
Open this publication in new window or tab >>Investigation of the Spatial Generation of Stimulated Raman Scattering Using Computer Simulation and Experimentation
2022 (English)In: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530, Vol. 26, no 11, p. 1307-1316Article in journal (Refereed) Published
Abstract [en]

Stimulated Raman scattering is a phenomenon with potential use in providing real-time molecular information in three-dimensions (3D) of a sample using imaging. For precise imaging, the knowledge about the spatial generation of stimulated Raman scattering is essential. To investigate the spatial behavior in an idealized case, computer simulations and experiments were performed. For the computer simulations, diffraction theory was used for the beam propagation complemented with nonlinear phase modulation describing the interaction between the light and matter. For the experiments, a volume of ethanol was illuminated by an expanded light beam and a plane inside the volume was imaged in transmission. For generating stimulated Raman scattering, a pump beam was focused into this volume and led to a beam dump after passing the volume. The pulse duration of the two beams were 6 ns and the pump beam energy ranged from 1 to 27 mJ. The effect of increasing pump power on the spatial distribution of the Raman gain and the spatial growth of the signal at different interaction lengths between the beam and the sample was investigated. The spatial width of the region where the stimulated Raman scattering signal was generated for experiments and simulation was 0.21 and 0.09 mm, respectively. The experimental and simulation results showed that most of the stimulated Raman scattering is generated close to the pump beam focus and the maximum peak of the Stokes intensity spatially comes shortly after the peak of the pump intensity.

Place, publisher, year, edition, pages
Sage Publications, 2022
Keywords
Stimulated Raman scattering, simulations, experiments, spatial distribution, spatial rate
National Category
Atom and Molecular Physics and Optics Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-90344 (URN)10.1177/00037028221123593 (DOI)000872145200003 ()36281542 (PubMedID)2-s2.0-85140561101 (Scopus ID)
Funder
Luleå University of TechnologyThe Kempe FoundationsSwedish Foundation for Strategic Research, ITM17-0056
Note

Validerad;2022;Nivå 2;2022-11-03 (sofila)

Available from: 2022-04-21 Created: 2022-04-21 Last updated: 2023-09-05Bibliographically approved
Eriksson, R., Gren, P., Sjödahl, M. & Ramser, K. (2021). 3D Spatial Control of Stimulated Raman Scattering Using a Phase Spatial Light Modulator. In: Proceedings OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP): . Paper presented at OSA Imaging and Applied Optics Congress 2021, Washington, DC, United States [Virtual], July 19-23, 2021. Optical Society of America, Article ID 3Th2D.4.
Open this publication in new window or tab >>3D Spatial Control of Stimulated Raman Scattering Using a Phase Spatial Light Modulator
2021 (English)In: Proceedings OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP), Optical Society of America, 2021, article id 3Th2D.4Conference paper, Published paper (Refereed)
Abstract [en]

Species specific 3D imaging requires control of where in the sample stimulated Raman gain is achieved. By using a phase spatial light modulator the signal position can be calculated, controlled and directly imaged in 3D.

 

Place, publisher, year, edition, pages
Optical Society of America, 2021
National Category
Atom and Molecular Physics and Optics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-87595 (URN)2-s2.0-85166464442 (Scopus ID)
Conference
OSA Imaging and Applied Optics Congress 2021, Washington, DC, United States [Virtual], July 19-23, 2021
Note

ISBN för värdpublikation: 978-1-943580-89-7

Available from: 2021-10-22 Created: 2021-10-22 Last updated: 2023-09-05Bibliographically approved
Knoepp, F., Wahl, J., Andersson, A., Kraut, S., Sommer, N., Weissmann, N. & Ramser, K. (2021). A Microfluidic System for Simultaneous Raman Spectroscopy, Patch-Clamp Electrophysiology, and Live-Cell Imaging to Study Key Cellular Events of Single Living Cells in Response to Acute Hypoxia. Small Methods, 5(10), Article ID 2100470.
Open this publication in new window or tab >>A Microfluidic System for Simultaneous Raman Spectroscopy, Patch-Clamp Electrophysiology, and Live-Cell Imaging to Study Key Cellular Events of Single Living Cells in Response to Acute Hypoxia
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2021 (English)In: Small Methods, E-ISSN 2366-9608, Vol. 5, no 10, article id 2100470Article in journal (Refereed) Published
Abstract [en]

The ability to sense changes in oxygen availability is fundamentally important for the survival of all aerobic organisms. However, cellular oxygen sensing mechanisms and pathologies remain incompletely understood and studies of acute oxygen sensing, in particular, have produced inconsistent results. Current methods cannot simultaneously measure the key cellular events in acute hypoxia (i.e., changes in redox state, electrophysiological properties, and mechanical responses) at controlled partial pressures of oxygen (pO2). The lack of such a comprehensive method essentially contributes to the discrepancies in the field. A sealed microfluidic system that combines i) Raman spectroscopy, ii) patch-clamp electrophysiology, and iii) live-cell imaging under precisely controlled pO2 have therefore been developed. Merging these modalities allows label-free and simultaneous observation of oxygen-dependent alterations in multiple cellular redox couples, membrane potential, and cellular contraction. This technique is adaptable to any cell type and allows in-depth insight into acute oxygen sensing processes underlying various physiologic and pathologic conditions. 

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
National Category
Other Medical Engineering
Research subject
Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-86830 (URN)10.1002/smtd.202100470 (DOI)000689682700001 ()34927935 (PubMedID)2-s2.0-85113152558 (Scopus ID)
Funder
Swedish Research Council, 2016–04220
Note

Validerad;2021;Nivå 2;2021-11-03 (beamah);

Forskningsfinansiär: Deutsche Forschungsgemeinschaft (452531259, 268555672); CRC 1213 (A06)

Available from: 2021-08-26 Created: 2021-08-26 Last updated: 2023-09-05Bibliographically approved
Lindahl, O. A., Bäcklund, T., Ramser, K., Liv, P., Ljungberg, B. & Bergh, A. (2021). A tactile resonance sensor for prostate cancer detection – evaluation on human prostate tissue. Biomedical Engineering & Physics Express, 7(2), Article ID 025017.
Open this publication in new window or tab >>A tactile resonance sensor for prostate cancer detection – evaluation on human prostate tissue
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2021 (English)In: Biomedical Engineering & Physics Express, E-ISSN 2057-1976, Vol. 7, no 2, article id 025017Article in journal (Refereed) Published
Abstract [en]

Prostate cancer surgery risks erectile problems and incontinence for the patient. An instrument for guiding surgeons to avoid nerve bundle damage and ensure complete cancer removal is desirable. We present a tactile resonance sensor made of PZT ceramics, mounted in a 3D motorized translation stage for scanning and measuring tissue stiffness for detecting cancer in human prostate. The sensor may be used during surgery for guidance, scanning the prostate surface for the presence of cancer, indicating migration of cancer cells into surrounding tissue. Ten fresh prostates, obtained from patients undergoing prostate cancer surgery, were cut into 0.5 cm thick slices. Each slice was measured for tissue stiffness at about 25 different sites and compared to histology for validation cancer prediction by stiffness. The statistical analysis was based on a total of 148 sites with non-cancer and 40 sites with cancer. Using a generalized linear mixed model (GLMM), the stiffness data predicted cancer with an area under the curve of 0.74, after correcting for overfitting using bootstrap validation. Mean prostate stiffness on the logarithmic scale (p = 0.015) and standardized Z-scores (p = 0.025) were both significant predictors of cancer. This study concludes that stiffness measured by the tactile resonance sensor is a significant predictor of prostate cancer with potential for future development towards a clinical instrument for surgical guidance.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2021
Keywords
Prostate cancer, resonance sensor, stiffness
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-83028 (URN)10.1088/2057-1976/abe681 (DOI)000624514500001 ()33588385 (PubMedID)2-s2.0-85103171622 (Scopus ID)
Funder
Vinnova
Note

Validerad;2021;Nivå 2;2021-03-02 (johcin)

Available from: 2021-02-22 Created: 2021-02-22 Last updated: 2022-03-24Bibliographically approved
Phounglamcheik, A., Vila, R., Kienzl, N., Wang, L., Hedayati, A., Broström, M., . . . Umeki, K. (2021). CO2 Gasification Reactivity of Char from High-Ash Biomass. ACS Omega, 6(49), 34115-34128
Open this publication in new window or tab >>CO2 Gasification Reactivity of Char from High-Ash Biomass
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2021 (English)In: ACS Omega, E-ISSN 2470-1343, Vol. 6, no 49, p. 34115-34128Article in journal (Refereed) Published
Abstract [en]

Biomass char produced from pyrolysis processes is of great interest to be utilized as renewable solid fuels or materials. Forest byproducts and agricultural wastes are low-cost and sustainable biomass feedstocks. These biomasses generally contain high amounts of ash-forming elements, generally leading to high char reactivity. This study elaborates in detail how chemical and physical properties affect CO2 gasification rates of high-ash biomass char, and it also targets the interactions between these properties. Char produced from pine bark, forest residue, and corncobs (particle size 4–30 mm) were included, and all contained different relative compositions of ash-forming elements. Acid leaching was applied to further investigate the influence of inorganic elements in these biomasses. The char properties relevant to the gasification rate were analyzed, that is, elemental composition, specific surface area, and carbon structure. Gasification rates were measured at an isothermal condition of 800 °C with 20% (vol.) of CO2 in N2. The results showed that the inorganic content, particularly K, had a stronger effect on gasification reactivity than specific surface area and aromatic cluster size of the char. At the gasification condition utilized in this study, K could volatilize and mobilize through the char surface, resulting in high gasification reactivity. Meanwhile, the mobilization of Ca did not occur at the low temperature applied, thus resulting in its low catalytic effect. This implies that the dispersion of these inorganic elements through char particles is an important reason behind their catalytic activity. Upon leaching by diluted acetic acid, the K content of these biomasses substantially decreased, while most of the Ca remained in the biomasses. With a low K content in leached biomass char, char reactivity was determined by the active carbon surface area.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2021
National Category
Energy Engineering
Research subject
Energy Engineering; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-88540 (URN)10.1021/acsomega.1c05728 (DOI)000757388000083 ()34926959 (PubMedID)2-s2.0-85120655810 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-01-01 (johcin)

Available from: 2021-12-20 Created: 2021-12-20 Last updated: 2022-03-17Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-3268-1691

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