Journal articles on the topic 'IR hyperspectral imaging'
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1
Saari, H., A. Akujärvi, C. Holmlund, H. Ojanen, J. Kaivosoja, A. Nissinen, and O. Niemeläinen. "VISIBLE, VERY NEAR IR AND SHORT WAVE IR HYPERSPECTRAL DRONE IMAGING SYSTEM FOR AGRICULTURE AND NATURAL WATER APPLICATIONS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W3 (October 19, 2017): 165–70. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w3-165-2017.
Abstract:
The accurate determination of the quality parameters of crops requires a spectral range from 400&thinsp;nm to 2500&thinsp;nm (Kawamura et al., 2010, Thenkabail et al., 2002). Presently the hyperspectral imaging systems that cover this wavelength range consist of several separate hyperspectral imagers and the system weight is from 5 to 15&thinsp;kg. In addition the cost of the Short Wave Infrared (SWIR) cameras is high (~&thinsp;50&thinsp;k€). VTT has previously developed compact hyperspectral imagers for drones and Cubesats for Visible and Very near Infrared (VNIR) spectral ranges (Saari et al., 2013, Mannila et al., 2013, Näsilä et al., 2016). Recently VTT has started to develop a hyperspectral imaging system that will enable imaging simultaneously in the Visible, VNIR, and SWIR spectral bands. The system can be operated from a drone, on a camera stand, or attached to a tractor. The targeted main applications of the DroneKnowledge hyperspectral system are grass, peas, and cereals. In this paper the characteristics of the built system are shortly described. The system was used for spectral measurements of wheat, several grass species and pea plants fixed to the camera mount in the test fields in Southern Finland and in the green house. The wheat, grass and pea field measurements were also carried out using the system mounted on the tractor. The work is part of the Finnish nationally funded <q>DroneKnowledge – Towards knowledge based export of small UAS remote sensing technology</q> project.
2
Jang, Hyukjin, Ashtamurthy S. Pawate, Rohit Bhargava, and Paul J. A. Kenis. "Polymeric microfluidic continuous flow mixer combined with hyperspectral FT-IR imaging for studying rapid biomolecular events." Lab on a Chip 19, no. 15 (2019): 2598–609. http://dx.doi.org/10.1039/c9lc00182d.
3
Paterova, Anna V., Sivakumar M. Maniam, Hongzhi Yang, Gianluca Grenci, and Leonid A. Krivitsky. "Hyperspectral infrared microscopy with visible light." Science Advances 6, no. 44 (October 2020): eabd0460. http://dx.doi.org/10.1126/sciadv.abd0460.
Abstract:
Hyperspectral microscopy is an imaging technique that provides spectroscopic information with high spatial resolution. When applied in the relevant wavelength region, such as in the infrared (IR), it can reveal a rich spectral fingerprint across different regions of a sample. Challenges associated with low efficiency and high cost of IR light sources and detector arrays have limited its broad adoption. Here, we introduce a new approach to IR hyperspectral microscopy, where the IR spectral map is obtained with off-the-shelf components built for visible light. The method is based on the nonlinear interference of correlated photons generated via parametric down-conversion. In this proof-of-concept we demonstrate the chemical mapping of a patterned sample, where different areas have distinctive IR spectroscopic fingerprints. The method provides a wide field of view, fast readout, and negligible heat delivered to the sample, which opens prospects for its further development for applications in material and biological studies.
4
Hermes, M., R. Brandstrup Morrish, L. Huot, L. Meng, S. Junaid, J. Tomko, G. R. Lloyd, et al. "Mid-IR hyperspectral imaging for label-free histopathology and cytology." Journal of Optics 20, no. 2 (January 24, 2018): 023002. http://dx.doi.org/10.1088/2040-8986/aaa36b.
5
Huret, Nathalie, Charlotte Segonne, Sébastien Payan, Giuseppe Salerno, Valéry Catoire, Yann Ferrec, Tjarda Roberts, et al. "Infrared Hyperspectral and Ultraviolet Remote Measurements of Volcanic Gas Plume at MT Etna during IMAGETNA Campaign." Remote Sensing 11, no. 10 (May 17, 2019): 1175. http://dx.doi.org/10.3390/rs11101175.
Abstract:
Quantification of gaseous emission fluxes from volcanoes can yield valuable insights on processes occurring in the Earth’s interior as part of hazard monitoring. It is also an important task in the framework of climate change, in order to refine estimates of natural emissions. Passive open-path UltraViolet (UV) scattered observation by UV camera allows the imaging of volcanic plumes and evaluation of sulfur dioxide (SO2) fluxes at high temporal resolution during daytime. Another technique of imaging is now available in the InfraRed (IR) spectral domain. Infrared hyperspectral imagers have the potential to overcome the boundary of daytime sampling of the UV, providing measurements also during the night and giving access simultaneously to additional relevant gas species. In this context the IMAGETNA campaign of measurements took place at Mt Etna (Italy) in June 2015. Three different IR imagers (commercial and under developments) were deployed, together with a Fourier Transform InfraRed spectrometer (FTIR) instrument, a UV camera, a Long Wavelength InfraRed (LWIR) camera and a radiometer. We present preliminary results obtained by the two IR cameras under development, and then the IR hyperspectral imager results, coming from full physics retrieval, are compared to those of the UV camera. The comparison points out an underestimation of the SO2 Slant Column Densities (SCD) of the UV camera by a factor of 3.6. The detailed study of the retrieved SO2 SCD highlights the promising application of IR imaging in volcanology for remotely volcanic plume gas measurements. It also provides a way to investigate uncertainties in the SO2 SCD imaging in the UV and the IR.
6
Azarfar, Ghazal, Ebrahim Aboualizadeh, Nicholas M. Walter, Simona Ratti, Camilla Olivieri, Alessandra Norici, Michael Nasse, Achim Kohler, Mario Giordano, and Carol J. Hirschmugl. "Estimating and correcting interference fringes in infrared spectra in infrared hyperspectral imaging." Analyst 143, no. 19 (2018): 4674–83. http://dx.doi.org/10.1039/c8an00093j.
7
Malak, Henryk, Petr Herman, Wayne Moore, and Jaroslav Vecer. "High Performance Hyperspectral Imager for Microimaging." Microscopy and Microanalysis 7, S2 (August 2001): 14–15. http://dx.doi.org/10.1017/s1431927600026143.
Abstract:
A high performance hyperspectral imager with high light throughput suitable for microscopy and analytical imaging was built and tested. The imager utilizes phenomenon of optical activity. The new technique provides a continuous spectral range of several hundreds of nanometers starting in deep UV. Similar spectral range starting in the near IR is also achievable.A performance of a low cost implementation of the new technology is presented. The imager has a form of a microscope adaptor, which is inserted between the microscope and a low-cost 8-bit CCD camera. The resulting instrument is simple, robust, and highly compact. The imager module is placed in-line to the microscope imaging system and does not introduce observable image aberrations. Advantageously, the imager is transparent to conventional imaging operations, thus with the imager in-place there is no need for reconfiguration of the microscope to switch between conventional and hyperspectral video/digital imaging modes.The presented spectral imager answers the need for a practical, sensitive, compact, and affordable imaging spectrometer. The instrument is well suited for a broad range of applications requiring rapid parallel acquisition of highly resolved concurrent spatial and spectral information such as high throughput screening, biochip analysis, remote sensing or nondestructive semiconductor testing.
8
Rhoby, Michael R., David L. Blunck, and Kevin C. Gross. "Mid-IR hyperspectral imaging of laminar flames for 2-D scalar values." Optics Express 22, no. 18 (August 29, 2014): 21600. http://dx.doi.org/10.1364/oe.22.021600.
9
Babini, Agnese, Phil Green, Sony George, and Jon Yngve Hardeberg. "Comparison of Hyperspectral Imaging and Fiber-Optic Reflectance Spectroscopy for Reflectance and Transmittance Measurements of Colored Glass." Heritage 5, no. 3 (June 23, 2022): 1401–19. http://dx.doi.org/10.3390/heritage5030073.
Abstract:
The work presented in this paper is part of a wider research project, which aims at documenting and analyzing stained glass windows by means of hyperspectral imaging. This technique shares some similarities with UV-VIS-IR spectroscopy, as they both provide spectral information; however, spectral imaging has the additional advantage of providing spatial information, since a spectrum can be collected in each pixel of the image. Compared to UV-VIS-IR spectroscopy, spectral imaging has rarely been used for the investigation of stained glass windows. One of the objectives of this paper is, thus, to compare the performance of these two instruments to validate the results of hyperspectral imaging. The second objective is to evaluate the potential of analyzing colored-glass pieces in reflectance modality and compare the results with those obtained in transmittance, in order to highlight the differences and similarities between the two approaches. The geometry of the systems and the backing material for the glass, as well as the characteristics of the glass pieces, are discussed. L*a*b* values obtained from the spectra, as well as the calculated color difference ΔE00, are provided, to show the degree of agreement between the instruments and the two measurement modalities.
10
Honda, Reo, Meguya Ryu, Masayuki Moritake, Armandas Balčytis, Vygantas Mizeikis, Jitraporn Vongsvivut, Mark J. Tobin, et al. "Infrared Polariscopy Imaging of Linear Polymeric Patterns with a Focal Plane Array." Nanomaterials 9, no. 5 (May 13, 2019): 732. http://dx.doi.org/10.3390/nano9050732.
Abstract:
Polariscopy is demonstrated using hyperspectral imaging with a focal plane array (FPA) detector in the infrared (IR) spectral region under illumination by thermal and synchrotron light sources. FPA Fourier-transform IR (FTIR) imaging microspectroscopy is useful for monitoring real time changes at specific absorption bands when combined with a high brightness synchrotron source. In this study, several types of samples with unique structural motifs were selected and used for assessing the capability of polariscopy under this FPA-FTIR imaging technique. It was shown that the time required for polariscopy at IR wavelengths can be substantially reduced by the FPA-FTIR imaging approach. By using natural and laser fabricated polymers with sub-wavelength features, alignment of absorbing molecular dipoles and higher order patterns (laser fabricated structures) were revealed. Spectral polariscopy at the absorption peaks can reveal the orientation of sub-wavelength patterns (even when they are not spatially resolved) or the orientation of the absorbing dipoles.
11
Wang, L., Y. Han, X. Jin, Y. Chen, and D. A. Tremblay. "Radiometric consistency assessment of hyperspectral infrared sounders." Atmospheric Measurement Techniques 8, no. 11 (November 19, 2015): 4831–44. http://dx.doi.org/10.5194/amt-8-4831-2015.
Abstract:
Abstract. The radiometric and spectral consistency among the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) is fundamental for the creation of long-term infrared (IR) hyperspectral radiance benchmark data sets for both intercalibration and climate-related studies. In this study, the CrIS radiance measurements on Suomi National Polar-orbiting Partnership (SNPP) satellite are directly compared with IASI on MetOp-A and MetOp-B at the finest spectral scale and with AIRS on Aqua in 25 selected spectral regions through simultaneous nadir overpass (SNO) observations in 2013, to evaluate radiometric consistency of these four hyperspectral IR sounders. The spectra from different sounders are paired together through strict spatial and temporal collocation. The uniform scenes are selected by examining the collocated Visible Infrared Imaging Radiometer Suite (VIIRS) pixels. Their brightness temperature (BT) differences are then calculated by converting the spectra onto common spectral grids. The results indicate that CrIS agrees well with IASI on MetOp-A and IASI on MetOp-B at the long-wave IR (LWIR) and middle-wave IR (MWIR) bands with 0.1–0.2 K differences. There are no apparent scene-dependent patterns for BT differences between CrIS and IASI for individual spectral channels. CrIS and AIRS are compared at the 25 spectral regions for both polar and tropical SNOs. The combined global SNO data sets indicate that the CrIS–AIRS BT differences are less than or around 0.1 K among 21 of 25 spectral regions and they range from 0.15 to 0.21 K in the remaining four spectral regions. CrIS–AIRS BT differences in some comparison spectral regions show weak scene-dependent features.
12
Wang, L., Y. Han, X. Jin, Y. Chen, and D. A. Tremblay. "Radiometric consistency assessment of hyperspectral infrared sounders." Atmospheric Measurement Techniques Discussions 8, no. 7 (July 14, 2015): 7161–99. http://dx.doi.org/10.5194/amtd-8-7161-2015.
Abstract:
Abstract. The radiometric and spectral consistency among the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) is fundamental for the creation of long-term infrared (IR) hyperspectral radiance benchmark datasets for both inter-calibration and climate-related studies. In this study, the CrIS radiance measurements on Suomi National Polar-orbiting Partnership (SNPP) satellite are directly compared with IASI on MetOp-A and -B at the finest spectral scale and with AIRS on Aqua in 25 selected spectral regions through one year of simultaneous nadir overpass (SNO) observations to evaluate radiometric consistency of these four hyperspectral IR sounders. The spectra from different sounders are paired together through strict spatial and temporal collocation. The uniform scenes are selected by examining the collocated Visible Infrared Imaging Radiometer Suite (VIIRS) pixels. Their brightness temperature (BT) differences are then calculated by converting the spectra onto common spectral grids. The results indicate that CrIS agrees well with IASI on MetOp-A and IASI on MetOp-B at the longwave IR (LWIR) and middle-wave IR (MWIR) bands with 0.1–0.2 K differences. There are no apparent scene-dependent patterns for BT differences between CrIS and IASI for individual spectral channels. CrIS and AIRS are compared at the 25 spectral regions for both Polar and Tropical SNOs. The combined global SNO datasets indicate that, the CrIS-AIRS BT differences are less than or around 0.1 K among 21 of 25 comparison spectral regions and they range from 0.15 to 0.21 K in the remaining 4 spectral regions. CrIS-AIRS BT differences in some comparison spectral regions show weak scene-dependent features.
13
Gao, Bo-Cai, and Rong-Rong Li. "FVI—A Floating Vegetation Index Formed with Three Near-IR Channels in the 1.0–1.24 μm Spectral Range for the Detection of Vegetation Floating over Water Surfaces." Remote Sensing 10, no. 9 (September 7, 2018): 1421. http://dx.doi.org/10.3390/rs10091421.
Abstract:
Through the analysis of hyperspectral imaging data collected over water surfaces covered by floating vegetation, such as Sargassum and algae, we observed that the spectra commonly contain a reflectance peak centered near 1.07 μm. This peak results from the competing effects between the well-known vegetation reflectance plateau in the 0.81–1.3 μm spectral range and the absorption effects above 0.75 μm by liquid water within the vegetation and in the surrounding water bodies. In this article, we propose a new index, namely the floating vegetation index (FVI), for the hyperspectral remote sensing of vegetation over surface layers of oceans and inland lakes. In the formulation of the FVI, one channel centered near 1.0 μm and another 1.24 μm are used to form a linear baseline. The reflectance value of the third channel centered at the 1.07-μm reflectance peak above the baseline is defined as the FVI. Hyperspectral imaging data acquired with the AVIRIS (Airborne Visible Infrared Imaging Spectrometer) instrument over the Gulf of Mexico and over salt ponds near Moffett Field in southern portions of the San Francisco Bay were used to demonstrate the success in detecting Sargassum and floating algae with this index. It is expected that the use of this index for the global detection of floating vegetation from hyperspectral imaging data to be acquired with future satellite sensors will result in improved detection and therefore enhanced capability in estimating primary production, a measure of how much carbon is fixed per unit area per day by oceans and inland lakes.
14
Askari, Mohammad Sadegh, Sharon M. O'Rourke, and Nicholas M. Holden. "A comparison of point and imaging visible-near infrared spectroscopy for determining soil organic carbon." Journal of Near Infrared Spectroscopy 26, no. 2 (April 2018): 133–46. http://dx.doi.org/10.1177/0967033518766668.
Abstract:
This study evaluated whether the accuracy of soil organic carbon measurement by laboratory hyperspectral imaging can match that of standard point spectroscopy operating in the visible–near infrared. Hyperspectral imaging allows a greater amount of spectral information to be collected from the soil sample compared to standard spectroscopy, accounting for greater sample representation. A total of 375 representative Irish soils were scanned by two-point spectrometers (a Foss NIR Systems 6500 labelled S-1 and a Varian FT-IR 3100 labelled S-2) and two laboratory hyperspectral imaging systems (two push broom line-scanning hyperspectral imaging systems manufactured by DV optics and Spectral Imaging Ltd, respectively, labelled S-3 and S-4). The objectives were (a) to compare the predictive ability of spectral datasets for soil organic carbon prediction for each instrument evaluated and (b) to assess the impact of imposing a common wavelength range and spectral resolution on soil organic carbon model accuracy. These objectives examined the predictive ability of spectral datasets for soil organic carbon prediction based on optimal settings of each instrument in (a) and introduced a constraint in wavelength range and spectral resolution to achieve common settings for instruments in (b). Based on optimal settings for each instrument, the deviation (root-mean square error of prediction) from the best fit line between laboratory measured and predicted soil organic carbon, ranked the instruments as S-1 (26.3 g kg−1) < S-2 (29.4 g kg−1) < S-3 (34.3 g kg−1) < S-4 (41.1 g kg−1). The S-1 model outperformed in all partial least squares regression performance indicators, and across all spectral ranges, and produced the most favourable outcomes in means testing, variance testing and identification of significant variables. It is assumed that a larger wavelength range produced more accurate soil organic carbon predictions for S-1 and S-2. Under common instrument settings, the prediction accuracy for S-3 that was almost equal to S-1. It is concluded that under standard operating procedures, greater soil sample representation captured by hyperspectral imaging can equal the quality of the spectra from point spectroscopy. This result is important for the development of laboratory hyperspectral imaging for soil image analysis.
15
Simongini, Camilla, Milda Pucetaite, Silvia Serranti, Martijn van Praagh, Edith Hammer, and Giuseppe Bonifazi. "Microplastics identification in landfill leachates by different spectroscopic techniques." Volume 18 - March 2022, no. 18 (March 31, 2022): 58–69. http://dx.doi.org/10.31025/2611-4135/2022.15169.
Abstract:
Discovered more than 40 years ago, microplastics have become a major environmental issue. With increasing global plastic production, microplastics are of growing concern. Landfills have been pinpointed as primary sources of microplastics to surface waters and they have, in fact, been identified and quantified as such. Due to their small size, different polymers and interfering non-plastic materials, microplastics are difficult to analyse in a complex matrix such as leachate. To elucidate the impact of pre-treatment on the performance of the most common microspectroscopical analytical methods employed, i.e., FT-IR and Raman, we re-examined previously pre-treated and analysed leachate samples. Additionally, we subjected duplicates of previously analysed samples to different concentrations of H2O2 with varied reaction times to digest and remove non-plastic organic matter. The pre-treated samples were subjected density separation and (re-)analysed by means of FT-IR and Raman microspectroscopy. Larger particles were also analysed by near-infrared (NIR) hyperspectral imaging. We found the concentration of H2O2 to impact the possibility of identifying and quantifying PET particles, with Raman scattering microspectroscopy enabling more particles to be counted than with FT-IR. This is likely due to the increased detectable particle size range, from around 50 μm for FT-IR to 1 μm for Raman scattering microspectroscopy. Optimized H2O2 concentration with subsequent density separation enabled to clearly identify numerous PE particles, but also PP, PS, and PET particles and carbon compounds with Raman scattering microspectroscopy. Hyperspectral imaging performed well for particles larger than 30 μm.
16
Borbas, E. Eva, Elisabeth Weisz, Chris Moeller, W. Paul Menzel, and Bryan A. Baum. "Improvement in tropospheric moisture retrievals from VIIRS through the use of infrared absorption bands constructed from VIIRS and CrIS data fusion." Atmospheric Measurement Techniques 14, no. 2 (February 15, 2021): 1191–203. http://dx.doi.org/10.5194/amt-14-1191-2021.
Abstract:
Abstract. An operational data product available for both the Suomi National Polar-orbiting Partnership (S-NPP) and National Oceanic and Atmospheric Administration-20 (NOAA-20) platforms provides high-spatial-resolution infrared (IR) absorption band radiances for Visible Infrared Imaging Radiometer Suite (VIIRS) based on a VIIRS and Crosstrack Infrared Sounder (CrIS) data fusion method. This study investigates the use of these IR radiances, centered at 4.5, 6.7, 7.3, 9.7, 13.3, 13.6, 13.9, and 14.2 µm, to construct atmospheric moisture products (e.g., total precipitable water and upper tropospheric humidity) and to evaluate their accuracy. Total precipitable water (TPW) and upper tropospheric humidity (UTH) retrieved from hyperspectral sounder CrIS measurements are provided at the associated VIIRS sensor's high spatial resolution (750 m) and are compared subsequently to collocated operational Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and S-NPP VIIRS moisture products. This study suggests that the use of VIIRS IR absorption band radiances will provide continuity with Aqua MODIS moisture products.
17
Lasch, Peter, Maren Stämmler, Miao Zhang, Malgorzata Baranska, Alejandra Bosch, and Katarzyna Majzner. "FT-IR Hyperspectral Imaging and Artificial Neural Network Analysis for Identification of Pathogenic Bacteria." Analytical Chemistry 90, no. 15 (June 26, 2018): 8896–904. http://dx.doi.org/10.1021/acs.analchem.8b01024.
18
Bonifazi, Giuseppe, Francesco Di Maio, Fabio Potenza, and Silvia Serranti. "FT-IR Analysis and Hyperspectral Imaging Applied to Postconsumer Plastics Packaging Characterization and Sorting." IEEE Sensors Journal 16, no. 10 (May 2016): 3428–34. http://dx.doi.org/10.1109/jsen.2015.2449867.
19
Zubler, Alanna V., and Jeong-Yeol Yoon. "Proximal Methods for Plant Stress Detection Using Optical Sensors and Machine Learning." Biosensors 10, no. 12 (November 29, 2020): 193. http://dx.doi.org/10.3390/bios10120193.
Abstract:
Plant stresses have been monitored using the imaging or spectrometry of plant leaves in the visible (red-green-blue or RGB), near-infrared (NIR), infrared (IR), and ultraviolet (UV) wavebands, often augmented by fluorescence imaging or fluorescence spectrometry. Imaging at multiple specific wavelengths (multi-spectral imaging) or across a wide range of wavelengths (hyperspectral imaging) can provide exceptional information on plant stress and subsequent diseases. Digital cameras, thermal cameras, and optical filters have become available at a low cost in recent years, while hyperspectral cameras have become increasingly more compact and portable. Furthermore, smartphone cameras have dramatically improved in quality, making them a viable option for rapid, on-site stress detection. Due to these developments in imaging technology, plant stresses can be monitored more easily using handheld and field-deployable methods. Recent advances in machine learning algorithms have allowed for images and spectra to be analyzed and classified in a fully automated and reproducible manner, without the need for complicated image or spectrum analysis methods. This review will highlight recent advances in portable (including smartphone-based) detection methods for biotic and abiotic stresses, discuss data processing and machine learning techniques that can produce results for stress identification and classification, and suggest future directions towards the successful translation of these methods into practical use.
20
Kalashnikova, Angelina A. "Use of Infrared Imaging in Contemporary Source Studies." History 19, no. 8 (2020): 117–27. http://dx.doi.org/10.25205/1818-7919-2020-19-8-117-127.
Abstract:
The paper gives a brief overview of infrared (IR) imaging techniques and the cases of their applying to the study of ancient manuscripts and objects of cultural heritage. The method of IR reflectography is used in fine art research, which allows the visualization of details hidden by the paint layers with the help of a scanner. There are also the cases, when IR reflectography is implemented into papyrology with the purpose to make ancient papyri, that turned dark-brown, more legible. Thermography is also used both in studies of cultural heritage and written documents, such as research of bookbinding and supports. Multispectral analysis is a well-proven method of text visualization and digital restoration of ancient manuscripts, which usually is applied in palimpsest decipher. Then the paper considers the method that includes part of IR spectrum is hyperspectral analysis. It is also used in papyrology. Finally, the author observed method of near-infrared imaging (NIRI) and its use for different purposes of the source studies. The paper concludes by arguing the relevance of near-infrared analysis of paper-based historical documents as a key-element of source study. NIRI allows researchers to obtain digital copies of watermarks and investigate corrections of the text made with different inks. The paper provides reader with the technical recommendations on basic NIRI equipment. To sum up, the author declares that there is a possibility for NIRI to become an everyday routine practice for researchers in near future due to its ability to provide a basic analysis of paper, watermarks and ink.
21
Hughes, Caryn S., Mick D. Brown, Peter Gardner, Johnathan H. Shanks, Noel W. Clarke, and Melody Jimenez-Hernandez. "Renal cell carcinoma: A prognostic target for spectral pathology." Journal of Clinical Oncology 31, no. 6_suppl (February 20, 2013): 459. http://dx.doi.org/10.1200/jco.2013.31.6_suppl.459.
Abstract:
459 Background: In contrast to standard pathology, where stained cells and tissues are examined visually under a microscope, spectral pathology is the study of changes in cellular composition of unstained tissue using molecular fingerprint techniques, such as infrared and Raman spectroscopy. Hyperspectral images are collected which provide not only spatial information but also data of high dimensionality, probing the global biochemistry of the biological specimen in the mid-infrared range. Methods: 9 paraffin-embedded, formalin-fixed clear cell renal carcinoma tissue sections (8μm thick) of different grade, stage and with respective matched pairs, were floated onto infrared-transmitting substrates. After dewaxing, Fourier transform infrared imaging spectroscopy was performed on a Varian 670-IR spectrometer coupled with a Varian 620-IR imaging microscope (Agilent Technologies, CA) equipped with a 128×128 pixel Mercury-Cadmium-Telluride focal planar array detector. A hyperspectral image is obtained whereby each pixel records an infrared spectrum at a pixel resolution of ~5.5x5.5μm. Mosaic images were captured of full tissue specimens (one imaging tile equates to a tissue sampling area of ~700×700μm). Results: We have been able to detect the phenotype of ccRCC and observed a diminishing glycogen-rich signal during tumour progression towards high grade tissue. The spectral characteristics of ccRCC have been correlated with H and E, PAS, and CA-IX staining. Conclusions: Cancer metabolism can be tracked by lipid and glycogen infrared bands that carry a unique spectral signature, depending on tumour aggressiveness. The future focus is to generate a prognostic model for small renal masses.
22
Krauz, Lukáš, Petr Páta, Jan Bednář, and Miloš Klíma. "Quasi-collinear IR AOTF based on mercurous halide single crystals for spatio-spectral hyperspectral imaging." Optics Express 29, no. 9 (April 12, 2021): 12813. http://dx.doi.org/10.1364/oe.420571.
23
Capobianco, Giuseppe, Maria Paola Bracciale, Diego Sali, Francesca Sbardella, Paolo Belloni, Giuseppe Bonifazi, Silvia Serranti, Maria Laura Santarelli, and Mariangela Cestelli Guidi. "Chemometrics approach to FT-IR hyperspectral imaging analysis of degradation products in artwork cross-section." Microchemical Journal 132 (May 2017): 69–76. http://dx.doi.org/10.1016/j.microc.2017.01.007.
24
Garskaite, Edita, Andreas S. Flø, Antonius T. J. van Helvoort, Aivaras Kareiva, and Espen Olsen. "Investigations of near IR photoluminescence properties in TiO2:Nd,Yb materials using hyperspectral imaging methods." Journal of Luminescence 140 (August 2013): 57–64. http://dx.doi.org/10.1016/j.jlumin.2013.02.044.
25
Meléndez, Juan, and Guillermo Guarnizo. "Multispectral Mid-Infrared Camera System for Accurate Stand-Off Temperature and Column Density Measurements on Flames." Sensors 21, no. 24 (December 16, 2021): 8395. http://dx.doi.org/10.3390/s21248395.
Abstract:
Accurate measurement of temperature in flames is a challenging problem that has been successfully addressed by hyperspectral imaging. This technique is able to provide maps of not only temperature T (K) but also of column density Q (ppm·m) of the main chemical species. Industrial applications, however, require cheaper instrumentation and faster and simpler data analysis. In this work, the feasibility and performance of multispectral imaging for the retrieval of T and QCO2 in flames are studied. Both the hyperspectral and multispectral measurement methods are described and applied to a standard flame, with known T and QCO2, and to an ordinary Bunsen flame. Hyperspectral results, based on emission spectra with 0.5 cm−1 resolution, were found in previous works to be highly accurate, and are thus considered as the ground truth to compare with multispectral measurements of a mid-IR camera (3 to 5 μm) with a six interference filter wheel. Maps of T and Q obtained by both methods show that, for regions with T ≳1300 K, the average of relative errors in multispectral measurements is ∼5% for T (and can be reduced to ∼2.5% with a correction based on a linear regression) and ∼20% for Q. Results obtained with four filters are very similar; results with two filters are also similar for T but worse for Q.
26
Segonne, Charlotte, Nathalie Huret, Sébastien Payan, Mathieu Gouhier, and Valéry Catoire. "A Spectra Classification Methodology of Hyperspectral Infrared Images for Near Real-Time Estimation of the SO2 Emission Flux from Mount Etna with LARA Radiative Transfer Retrieval Model." Remote Sensing 12, no. 24 (December 16, 2020): 4107. http://dx.doi.org/10.3390/rs12244107.
Abstract:
Fast and accurate quantification of gas fluxes emitted by volcanoes is essential for the risk mitigation of explosive eruption, and for the fundamental understanding of shallow eruptive processes. Sulphur dioxide (SO2), in particular, is a reliable indicator to predict upcoming eruptions, and its systemic characterization allows the rapid assessment of sudden changes in eruptive dynamics. In this regard, infrared (IR) hyperspectral imaging is a promising new technology for accurately measure SO2 fluxes day and night at a frame rate down to 1 image per second. The thermal infrared region is not very sensitive to particle scattering, which is an asset for the study of volcanic plume. A ground based infrared hyperspectral imager was deployed during the IMAGETNA campaign in 2015 and provided high spectral resolution images of the Mount Etna (Sicily, Italy) plume from the North East Crater (NEC), mainly. The LongWave InfraRed (LWIR) hyperspectral imager, hereafter name Hyper-Cam, ranges between 850–1300 cm−1 (7.7–11.8 µm). The LATMOS (Laboratoire Atmosphères Milieux Observations Spatiales) Atmospheric Retrieval Algorithm (LARA), which is used to retrieve the slant column densities (SCD) of SO2, is a robust and a complete radiative transfer model, well adapted to the inversion of ground-based remote measurements. However, the calculation time to process the raw data and retrieve the infrared spectra, which is about seven days for the retrieval of one image of SO2 SCD, remains too high to infer near real-time (NRT) SO2 emission fluxes. A spectral image classification methodology based on two parameters extracting spectral features in the O3 and SO2 emission bands was developed to create a library. The relevance is evaluated in detail through tests. From data acquisition to the generation of SO2 SCD images, this method requires only ~40 s per image, which opens the possibility to infer NRT estimation of SO2 emission fluxes from IR hyperspectral imager measurements.
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Yao, Zhigang, Jun Li, Jinlong Li, and Hong Zhang. "Surface Emissivity Impact on Temperature and Moisture Soundings from Hyperspectral Infrared Radiance Measurements." Journal of Applied Meteorology and Climatology 50, no. 6 (June 2011): 1225–35. http://dx.doi.org/10.1175/2010jamc2587.1.
Abstract:
AbstractAn accurate land surface emissivity (LSE) is critical for the retrieval of atmospheric temperature and moisture profiles along with land surface temperature from hyperspectral infrared (IR) sounder radiances; it is also critical to assimilating IR radiances in numerical weather prediction models over land. To investigate the impact of different LSE datasets on Atmospheric Infrared Sounder (AIRS) sounding retrievals, experiments are conducted by using a one-dimensional variational (1DVAR) retrieval algorithm. Sounding retrievals using constant LSE, the LSE dataset from the Infrared Atmospheric Sounding Interferometer (IASI), and the baseline fit dataset from the Moderate Resolution Imaging Spectroradiometer (MODIS) are performed. AIRS observations over northern Africa on 1–7 January and 1–7 July 2007 are used in the experiments. From the limited regional comparisons presented here, it is revealed that the LSE from the IASI obtained the best agreement between the retrieval results and the ECMWF reanalysis, whereas the constant LSE gets the worst results when the emissivities are fixed in the retrieval process. The results also confirm that the simultaneous retrieval of atmospheric profile and surface parameters could reduce the dependence of soundings on the LSE choice and finally improve sounding accuracy when the emissivities are adjusted in the iterative retrieval. In addition, emissivity angle dependence is investigated with AIRS radiance measurements. The retrieved emissivity spectra from AIRS over the ocean reveal weak angle dependence, which is consistent with that from an ocean emissivity model. This result demonstrates the reliability of the 1DVAR simultaneous algorithm for emissivity retrieval from hyperspectral IR radiance measurements.
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Balbekova, Anna, Hans Lohninger, Geralda A. F. van Tilborg, Rick M. Dijkhuizen, Maximilian Bonta, Andreas Limbeck, Bernhard Lendl, et al. "Fourier Transform Infrared (FT-IR) and Laser Ablation Inductively Coupled Plasma–Mass Spectrometry (LA-ICP-MS) Imaging of Cerebral Ischemia: Combined Analysis of Rat Brain Thin Cuts Toward Improved Tissue Classification." Applied Spectroscopy 72, no. 2 (October 25, 2017): 241–50. http://dx.doi.org/10.1177/0003702817734618.
Abstract:
Microspectroscopic techniques are widely used to complement histological studies. Due to recent developments in the field of chemical imaging, combined chemical analysis has become attractive. This technique facilitates a deepened analysis compared to single techniques or side-by-side analysis. In this study, rat brains harvested one week after induction of photothrombotic stroke were investigated. Adjacent thin cuts from rats’ brains were imaged using Fourier transform infrared (FT-IR) microspectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The LA-ICP-MS data were normalized using an internal standard (a thin gold layer). The acquired hyperspectral data cubes were fused and subjected to multivariate analysis. Brain regions affected by stroke as well as unaffected gray and white matter were identified and classified using a model based on either partial least squares discriminant analysis (PLS-DA) or random decision forest (RDF) algorithms. The RDF algorithm demonstrated the best results for classification. Improved classification was observed in the case of fused data in comparison to individual data sets (either FT-IR or LA-ICP-MS). Variable importance analysis demonstrated that both molecular and elemental content contribute to the improved RDF classification. Univariate spectral analysis identified biochemical properties of the assigned tissue types. Classification of multisensor hyperspectral data sets using an RDF algorithm allows access to a novel and in-depth understanding of biochemical processes and solid chemical allocation of different brain regions.
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Raczkowska, Magda K., Paulina Koziol, Slawka Urbaniak-Wasik, Czeslawa Paluszkiewicz, Wojciech M. Kwiatek, and Tomasz P. Wrobel. "Influence of denoising on classification results in the context of hyperspectral data: High Definition FT-IR imaging." Analytica Chimica Acta 1085 (November 2019): 39–47. http://dx.doi.org/10.1016/j.aca.2019.07.045.
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Wróbel-Szkolak, Joanna, Anna Cwener, and Łukasz Komsta. "Novel Hyperspectral Analysis of Thin-Layer Chromatographic Plates—An Application to Fingerprinting of 70 Polish Grasses." Molecules 28, no. 9 (April 26, 2023): 3745. http://dx.doi.org/10.3390/molecules28093745.
Abstract:
The advantages of hyperspectral imaging in videodensitometry are presented and discussed with the example of extracts from 70 Polish grasses. An inexpensive microscope camera was modified to cover the infrared spectrum range, and then 11 combinations of illumination (254 nm, 366 nm, white light), together with various filters (no filter, IRCut, UV, cobalt glass, IR pass), were used to register RGB HDR images of the same plate. It was revealed that the resulting 33 channels of information could be compressed into 5–6 principal components and then visualized separately as grayscale images. We also propose a new approach called principal component artificial coloring of images (PCACI). It allows easy classification of chromatographic spots by presenting three PC components as RGB channels, providing vivid spots with artificial colors and visualizing six principal components on two color images. The infrared region brings additional information to the registered data, orthogonal to the other channels and not redundant with photos in the visible region. This is the first published attempt to use a hyperspectral camera in TLC and it can be clearly concluded that such an approach deserves routine use and further attention.
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Lasch, Peter, and Isao Noda. "Two-Dimensional Correlation Spectroscopy (2D-COS) for Analysis of Spatially Resolved Vibrational Spectra." Applied Spectroscopy 73, no. 4 (March 21, 2019): 359–79. http://dx.doi.org/10.1177/0003702818819880.
Abstract:
The last two decades have seen tremendous progress in the application of two-dimensional correlation spectroscopy (2D-COS) as a versatile analysis method for data series obtained using a large variety of different spectroscopic modalities, including infrared (IR) and Raman spectroscopy. The analysis technique is applicable to a series of spectra recorded under the influence of an external sample perturbation. Two-dimensional COS analysis is not only helpful to decipher correlations, which may exist between distinct spectral features, but can also be utilized to obtain the sequence of individual spectral changes. The focus of this review article is on the application of 2D-COS for analyzing spatially resolved data with special emphasis on hyperspectral imaging (HSI) study. In this review, we briefly introduce the fundamentals of the generalized 2D-COS analysis approach, discuss specific points of 2D-COS application to spatially resolved spectra and demonstrate essential aspects of data pre-processing for 2D-COS analysis of spatially resolved spectra. Based on illustrative examples, we show that 2D-COS is useful for spectral band assignment in HSI applications and demonstrate its utility for detecting subtle correlations between spectra features, or between features from different imaging modalities in the case of heterospectral (multimodal) HSI. Furthermore, a short overview on existing 2D-COS software tools is provided. It is hoped that this article represents not only a useful guideline for 2D-COS analyses of spatially resolved hyperspectral data but supports also further dissemination of the 2D-COS analysis method as a whole.
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Nallala, Jayakrupakar, Doriana Calabrese, Sarah Gosling, Esther Lips, Rachel Factor, Allison Hall, Sarah E. Pinder, et al. "Abstract P4-02-22: Breast microcalcification chemistry predicts DCIS prognosis." Cancer Research 83, no. 5_Supplement (March 1, 2023): P4–02–22—P4–02–22. http://dx.doi.org/10.1158/1538-7445.sabcs22-p4-02-22.
Abstract:
Abstract Introduction: Microcalcifications are a common feature in mammographic detection of ductal carcinoma in situ (DCIS), and occur in >80% of cases. Known to be present as type I (calcium oxalate-CaO) and type II (carbonated calcium hydroxyapatite-CHAP) microcalcifications, their association with DCIS and their role in the progression of DCIS to invasive breast cancer (IBC) remains unexplored. In an effort to understand the factors involved in DCIS prognosis, it is hypothesized that changes in the chemical composition of calcifications, in tandem with molecular changes in the surrounding soft tissue, will define patients with DCIS who will progress to develop IBC from those who remain with a stable DCIS phenotype. To this end, a novel label-free approach of hyperspectral imaging using mid-infrared (mid-IR) and Raman spectroscopy was used to probe calcification chemistry and molecular composition of the surrounding ductal and stromal soft tissue. The main aim of the work is to identify biomarkers for DCIS prognosis, based on chemical and molecular compositional changes of calcifications and the surrounding soft tissue. It is anticipated that the spectral biomarkers will provide patients and clinicians an informed risk assessment whether to undertake treatment for DCIS or to be placed under active surveillance. Methods: Tissue samples from 422 patient have been obtained and include (i) ‘pure DCIS’ (DCIS without recurrence) (n=193), (ii) ‘DCIS with invasive recurrence’ (DCIS from patients who subsequently were known to develop invasive disease) (n=123), (iii) ‘DCIS plus contemporaneous invasive cancer’ (n=44) and ‘benign’ (n=62) samples. Serial tissue sections were measured using mid-IR and Raman hyperspectral imaging approaches targeting the same calcification and soft tissue regions from specific DCIS ducts. Hyperspectral imaging data was initially pre-processed to digitally remove paraffin and unintended spectral interferences. The pre-processed data was subjected to cluster analysis followed by unsupervised and supervised machine learning classification models to identify spectral features associated with DCIS and its progression to IBC. Results: Cluster analysis based segmentation of hyperspectral images revealed histopathological features including calcifications, epithelium, necrotic areas, connective tissue and stroma. Spectra were extracted from each of the histopathological features using image coordinates, and biomodelling analysis was performed. Initial analysis of 314 calcification images from 170 patients with (i) ‘pure DCIS’ (n=118) and (ii) ‘DCIS with invasive recurrence’ (n=52) showed an area under the receiver operating characteristic (AUROC) mean value of 85% in distinguishing pure DCIS from DCIS that later recurred as IBC. The calcification features appeared to indicate pathology specific changes in phosphate and carbonate content as well as changes in magnesium whitlockite content. Similar analysis of the surrounding soft tissue spectral features showed an AUROC mean value of 85% (necrotic regions surrounding calcifications) and 76% (epithelium) respectively. The epithelial features showed changes in protein secondary structure and content, which together with the calcification changes indicate structural remodelling in DCIS that progresses to IBC, from those that do not. Perspectives: In the ongoing analyses of imaging data from 422 patients, it is anticipated that molecular/structural features from calcification and soft tissue imaging data will provide important cues in understanding DCIS prognosis and could be a promising way forward in determining management of DCIS risk and treatment underpinned by the identification of specific discriminatory spectral markers. Acknowledgments: This work was supported by Cancer Research UK and by KWF Kankerbestrijding (ref. C38317/A24043). Citation Format: Jayakrupakar Nallala, Doriana Calabrese, Sarah Gosling, Esther Lips, Rachel Factor, Allison Hall, Sarah E. Pinder, Ihssane Bouybayoune, Lorraine King, Jeffrey Marks, Thomas Lynch, Donna Pinto, Jelle Wesseling, E Shelley Hwang, Keith Rogers, Nick Stone. Breast microcalcification chemistry predicts DCIS prognosis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-02-22.
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Maschhoff, Kevin, John Polizotti, Hartmut Aumann, Joel Susskind, Dennis Bowler, Christopher Gittins, Mark Janelle, and Samuel Fingerman. "Concept Development and Risk Reduction for MISTiC Winds, A Micro-Satellite Constellation Approach for Vertically Resolved Wind and IR Sounding Observations in the Troposphere." Remote Sensing 11, no. 18 (September 18, 2019): 2169. http://dx.doi.org/10.3390/rs11182169.
Abstract:
MISTiC Winds is an instrument and constellation mission approach to simultaneously observe the global thermodynamic state and the vertically resolved horizontal wind field in the troposphere from LEO SSO. The instrument is a wide-field imaging spectrometer operated in the 4.05–5.75 μm range, with the spectral resolution, sampling, radiometric sensitivity, and stability needed to provide temperature and water vapor soundings of the atmosphere, with 1 km vertical resolution in the troposphere-comparable to those of NASA’s atmospheric infrared sounder (AIRS). These instruments have much higher spatial resolution (<3 km at nadir) and finer spatial sampling than current hyperspectral sounders, allowing a sequence of such observations from several micro-satellites in an orbital plane with short time separation, from which atmospheric motion vector (AMV) winds are derived. AMVs for both cloud-motion and water vapor-motion, derived from hyperspectral imagery, will have improved velocity resolution relative to AMVs obtained from multi-spectral instruments operating in GEO. MISTiC’s extraordinarily small size, low mass (<15 kg), and minimal cooling requirements can be accommodated aboard an ESPA-class microsatellite. Low fabrication and launch costs enable this constellation to provide more frequent atmospheric observations than current-generation sounders provide, at much lower mission cost. Key technology and observation method risks have been reduced through recent laboratory and airborne (NASA ER2) testing funded under NASA’s Instrument Incubator Program and BAE Systems IR&D, and through an observing system simulation experiment performed by NASA GMAO. This approach would provide a valuable new capability for the study of the processes driving high-impact weather events, and critical high-resolution observations needed for future numerical weather prediction.
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Wang, Zhipeng, Flavio Iturbide-Sanchez, Peter Beierle, Kun Zhang, and Denis Tremblay. "Validation of CrIS Radiometric Performance through Its Comparison to ABI." Remote Sensing 14, no. 4 (February 12, 2022): 876. http://dx.doi.org/10.3390/rs14040876.
Abstract:
Radiometric intercomparison between satellite remote sensing instruments has become an increasingly common practice to monitor the stability and even the accuracy of their radiance products. The assessment also enables the evaluation of calibration improvements made to these products, as well as the identification and resolution of remaining calibration inadequacies. In this paper, the radiance products of the Cross-track Infrared Sounder (CrIS), an interferometer-based hyperspectral IR sounder in low Earth orbit (LEO), is compared with the level-1b (L1b) radiance products of the infrared (IR) bands of the Advanced Baseline Imager (ABI), an imaging radiometer in geostationary (GEO) orbit. Two CrIS instruments are currently in operation on S-NPP and NOAA-20 satellites, respectively, and two ABI instruments are in operation on GOES-16 and GOES-17 satellites, respectively. Radiometric intercomparisons are performed between each CrIS-ABI pair. An established procedure by GSICS for such GEO-LEO instrument comparison is principally followed to emulate the radiance of ABI IR bands from CrIS spectra of the collocated pixels to be compared with the actual ABI radiance. Results show that the long-term time series of CrIS-ABI radiance bias have been stable within 0.2 K for nearly all ABI IR bands within a spectral range from 3.7 μm to 13.3 μm, except those with known calibration issues. Miscellaneous calibration events that had occurred to either instrument and altered the biases are identified and explained. While the main goal of the work is to support the on-orbit Cal/Val of CrIS, including the future JPSS-2/3/4 CrIS, such observations can also be referenced to further improve the calibration of ABI.
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Go, Sujung, Jhoon Kim, Sang Seo Park, Mijin Kim, Hyunkwang Lim, Ji-Young Kim, Dong-Won Lee, and Jungho Im. "Synergistic Use of Hyperspectral UV-Visible OMI and Broadband Meteorological Imager MODIS Data for a Merged Aerosol Product." Remote Sensing 12, no. 23 (December 5, 2020): 3987. http://dx.doi.org/10.3390/rs12233987.
Abstract:
The retrieval of optimal aerosol datasets by the synergistic use of hyperspectral ultraviolet (UV)–visible and broadband meteorological imager (MI) techniques was investigated. The Aura Ozone Monitoring Instrument (OMI) Level 1B (L1B) was used as a proxy for hyperspectral UV–visible instrument data to which the Geostationary Environment Monitoring Spectrometer (GEMS) aerosol algorithm was applied. Moderate-Resolution Imaging Spectroradiometer (MODIS) L1B and dark target aerosol Level 2 (L2) data were used with a broadband MI to take advantage of the consistent time gap between the MODIS and the OMI. First, the use of cloud mask information from the MI infrared (IR) channel was tested for synergy. High-spatial-resolution and IR channels of the MI helped mask cirrus and sub-pixel cloud contamination of GEMS aerosol, as clearly seen in aerosol optical depth (AOD) validation with Aerosol Robotic Network (AERONET) data. Second, dust aerosols were distinguished in the GEMS aerosol-type classification algorithm by calculating the total dust confidence index (TDCI) from MODIS L1B IR channels. Statistical analysis indicates that the Probability of Correct Detection (POCD) between the forward and inversion aerosol dust models (DS) was increased from 72% to 94% by use of the TDCI for GEMS aerosol-type classification, and updated aerosol types were then applied to the GEMS algorithm. Use of the TDCI for DS type classification in the GEMS retrieval procedure gave improved single-scattering albedo (SSA) values for absorbing fine pollution particles (BC) and DS aerosols. Aerosol layer height (ALH) retrieved from GEMS was compared with Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data, which provides high-resolution vertical aerosol profile information. The CALIOP ALH was calculated from total attenuated backscatter data at 1064 nm, which is identical to the definition of GEMS ALH. Application of the TDCI value reduced the median bias of GEMS ALH data slightly. The GEMS ALH bias approximates zero, especially for GEMS AOD values of >~0.4 and GEMS SSA values of <~0.95. Finally, the AOD products from the GEMS algorithm and MI were used in aerosol merging with the maximum-likelihood estimation method, based on a weighting factor derived from the standard deviation of the original AOD products. With the advantage of the UV–visible channel in retrieving aerosol properties over bright surfaces, the combined AOD products demonstrated better spatial data availability than the original AOD products, with comparable accuracy. Furthermore, pixel-level error analysis of GEMS AOD data indicates improvement through MI synergy.
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Paradis, Marie-Chloé Michaud, François R. Doucet, Kheireddine Rifai, Lütfü Ç. Özcan, Nawfel Azami, and François Vidal. "ECORE: A New Fast Automated Quantitative Mineral and Elemental Core Scanner." Minerals 11, no. 8 (August 10, 2021): 859. http://dx.doi.org/10.3390/min11080859.
Abstract:
Scarce platinum group elements (PGE) are mainly concealed in massive sulfides, and finding economically viable ore bodies largely relies on their fast chemical mapping. Most core scanners provide incomplete mineralogical contents, but none also provide a complete chemical analysis including light elements. This study investigates the performance of a fully automated laser-induced breakdown spectroscopy (LIBS) core scanner, the ECORE, by comparing its reliability to a scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) mineral mapper and its speed to infrared diffuse reflectance hyperspectral imagers (IR-HSI). The LIBS elemental imaging has been put to the test in our previous work, as well as the high-resolution mineralogical mapping. This paper reports the scaling up analytical applicability of LIBS as a high performance and high-speed drill core scanner. The analysis of a full core tray in this study is the first and largest 7.62 megapixels image done by a LIBS core scanner to our knowledge. Both high-resolution and low-resolution data are put together to express both mineralogical and chemical content as a function of depth.
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Fang, Chenggege, Yang Han, and Fuzhong Weng. "Monitoring Asian Dust Storms from NOAA-20 CrIS Double CO2 Band Observations." Remote Sensing 14, no. 18 (September 18, 2022): 4659. http://dx.doi.org/10.3390/rs14184659.
Abstract:
Sand and dust storms (SDSs) are common environmental hazards in spring in Asian continent and have significant impacts on human health, weather, and climate. While many technologies have been developed to monitor SDSs, this study investigates the spectral characteristics of SDSs in satellite hyperspectral infrared observations and propose a new methodology to monitor the storms. An SDS emission and scattering index (SESI) is based on the differential responses of infrared CO2 shortwave and longwave IR bands to the scattering and emission of sand and dust particles. For a severe dust storm process during 14–17 March 2021, the SESI calculated by the Cross-track Infrared Sounder (CrIS) observations shows very negative values in the dusty region and is consistent with the spatial distribution of dust identified from the true-color RGB imagery and the dust RGB imagery of the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-20 Satellite. The use of the SESI index in the near-surface layer allows for monitoring of the dust storm process and enables an effective classification between surface variations and dust weather events.
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Santek, David, Sharon Nebuda, and Dave Stettner. "Demonstration and Evaluation of 3D Winds Generated by Tracking Features in Moisture and Ozone Fields Derived from AIRS Sounding Retrievals." Remote Sensing 11, no. 22 (November 6, 2019): 2597. http://dx.doi.org/10.3390/rs11222597.
Abstract:
For more than 15 years, polar winds from the Moderate Resolution Imaging Spectroradiometer (MODIS) imagery have been generated by the National Oceanic and Atmospheric Administration (NOAA) and the Cooperative Institute for Meteorological Satellite Studies (CIMSS). These datasets are a NOAA National Environmental Satellite, Data, and Information Service (NESDIS) operational satellite product that is used at more than 10 major numerical weather prediction (NWP) centers worldwide. The MODIS polar winds product is composed of both infrared window (IR-W) and water vapor (WV) tracked features. The WV atmospheric motion vectors (AMV) yield a better spatial distribution than the IR-W since both cloud and clear-sky features can be tracked in the WV images. As the new generation polar satellite-era begins with the Suomi National Polar-orbiting Partnership (S-NPP), there is currently no WV channel on the Visible/Infrared Imager/Radiometer Suite (VIIRS), resulting in a data gap with only IR-W derived AMVs possible. This scenario presents itself as an opportunity to evaluate hyperspectral infrared moisture retrievals from consecutive overlapping satellite polar passes to extract atmospheric motion from clear-sky regions on constant (and known) pressure surfaces, i.e., estimating winds in retrieval space rather than radiance space. Perhaps most significantly, this method has the potential to provide vertical wind profiles, as opposed to the current MODIS-derived single-level AMVs. In this study, the winds technique is applied to Atmospheric Infrared Sounder (AIRS) moisture retrievals from NASA’s Aqua satellite. The resulting winds are assimilated into the Goddard Earth Observing System Model, Version 5 (GEOS-5). The results are encouraging, as the AIRS retrieval polar AMVs have a similar quality as the MODIS AMVs and exhibit a positive impact in the hemispheric Day 4.5 to 6.5 forecasts for a one-month experiment in July 2012.
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Wenseleers, Wim, Maksiem Erkens, Miguel Angel Lopez Carrillo, Bea Botka, Sofie Cambre, and Juan Duque. "(Invited) Hyperspectral Detection of the Fluorescence Shift between Enantiomers of Empty and Water-Filled Single-Wall Carbon Nanotubes." ECS Meeting Abstracts MA2022-01, no. 9 (July 7, 2022): 725. http://dx.doi.org/10.1149/ma2022-019725mtgabs.
Abstract:
The unusually chiral-structure-dependent properties of single-wall carbon nanotubes (SWCNTs) are also strongly influenced by their internal and external environment, which can therefore be investigated through optical spectroscopy.[1,2] In order to study this influence in detail, we developed a hyperspectral IR fluorescence imaging setup based on a microscope with a liquid crystal tunable filter. By resolving the spectra of individual SWCNTs, and even along the length of SWCNTs, the effect of inhomogeneous broadening is largely eliminated, and spectral details can be resolved which are inaccessible in bulk spectroscopy. An automated image processing scheme is used to obtain statistics on large numbers of individual SWCNTs. In particular, we show that not only the spectral shift in emission between empty and water-filled[1] chirality sorted SWCNTs can be resolved, but even separate emission peaks are observed for the left- and right-handed enantiomers, which interact slightly differently with the chiral surfactant with which they are coated. The approach is particularly promising for the quantification of enantio-selective separation results. [1] W. Wenseleers et al., Adv. Mater. 19, 2274 (2007); S. Cambré and W. Wenseleers, Angew. Chem. 50, 2764 (2011); S. Cambré et al., ACS Nano 6, 2649 (2012). [2] J. Campo et al., ACS Nano 2021, 15, 2301−2317.
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Muller, Eric A., Thomas P. Gray, Zhou Zhou, Xinbin Cheng, Omar Khatib, Hans A. Bechtel, and Markus B. Raschke. "Vibrational exciton nanoimaging of phases and domains in porphyrin nanocrystals." Proceedings of the National Academy of Sciences 117, no. 13 (March 13, 2020): 7030–37. http://dx.doi.org/10.1073/pnas.1914172117.
Abstract:
Much of the electronic transport, photophysical, or biological functions of molecular materials emerge from intermolecular interactions and associated nanoscale structure and morphology. However, competing phases, defects, and disorder give rise to confinement and many-body localization of the associated wavefunction, disturbing the performance of the material. Here, we employ vibrational excitons as a sensitive local probe of intermolecular coupling in hyperspectral infrared scattering scanning near-field optical microscopy (IR s-SNOM) with complementary small-angle X-ray scattering to map multiscale structure from molecular coupling to long-range order. In the model organic electronic material octaethyl porphyrin ruthenium(II) carbonyl (RuOEP), we observe the evolution of competing ordered and disordered phases, in nucleation, growth, and ripening of porphyrin nanocrystals. From measurement of vibrational exciton delocalization, we identify coexistence of ordered and disordered phases in RuOEP that extend down to the molecular scale. Even when reaching a high degree of macroscopic crystallinity, identify significant local disorder with correlation lengths of only a few nanometers. This minimally invasive approach of vibrational exciton nanospectroscopy and -imaging is generally applicable to provide the molecular-level insight into photoresponse and energy transport in organic photovoltaics, electronics, or proteins.
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Zaukuu, John-Lewis Zinia, Eszter Benes, György Bázár, Zoltán Kovács, and Marietta Fodor. "Agricultural Potentials of Molecular Spectroscopy and Advances for Food Authentication: An Overview." Processes 10, no. 2 (January 24, 2022): 214. http://dx.doi.org/10.3390/pr10020214.
Abstract:
Meat, fish, coffee, tea, mushroom, and spices are foods that have been acknowledged for their nutritional benefits but are also reportedly targets of fraud and tampering due to their economic value. Conventional methods often take precedence for monitoring these foods, but rapid advanced instruments employing molecular spectroscopic techniques are gradually claiming dominance due to their numerous advantages such as low cost, little to no sample preparation, and, above all, their ability to fingerprint and detect a deviation from quality. This review aims to provide a detailed overview of common molecular spectroscopic techniques and their use for agricultural and food quality management. Using multiple databases including ScienceDirect, Scopus, Web of Science, and Google Scholar, 171 research publications including research articles, review papers, and book chapters were thoroughly reviewed and discussed to highlight new trends, accomplishments, challenges, and benefits of using molecular spectroscopic methods for studying food matrices. It was observed that Near infrared spectroscopy (NIRS), Infrared spectroscopy (IR), Hyperspectral imaging (his), and Nuclear magnetic resonance spectroscopy (NMR) stand out in particular for the identification of geographical origin, compositional analysis, authentication, and the detection of adulteration of meat, fish, coffee, tea, mushroom, and spices; however, the potential of UV/Vis, 1H-NMR, and Raman spectroscopy (RS) for similar purposes is not negligible. The methods rely heavily on preprocessing and chemometric methods, but their reliance on conventional reference data which can sometimes be unreliable, for quantitative analysis, is perhaps one of their dominant challenges. Nonetheless, the emergence of handheld versions of these techniques is an area that is continuously being explored for digitalized remote analysis.
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Hyman, David M. R., Michael J. Pavolonis, and Justin Sieglaff. "A Novel Approach to Estimating Time-Averaged Volcanic SO2 Fluxes from Infrared Satellite Measurements." Remote Sensing 13, no. 5 (March 4, 2021): 966. http://dx.doi.org/10.3390/rs13050966.
Abstract:
Long-term continuous time series of SO2 emissions are considered critical elements of both volcano monitoring and basic research into processes within magmatic systems. One highly successful framework for computing these fluxes involves reconstructing a representative time-averaged SO2 plume from which to estimate the SO2 source flux. Previous methods within this framework have used ancillary wind datasets from reanalysis or numerical weather prediction (NWP) to construct the mean plume and then again as a constrained parameter in the fitting. Additionally, traditional SO2 datasets from ultraviolet (UV) sensors lack altitude information, which must be assumed, to correctly calibrate the SO2 data and to capture the appropriate NWP wind level which can be a significant source of error. We have made novel modifications to this framework which do not rely on prior knowledge of the winds and therefore do not inherit errors associated with NWP winds. To perform the plume rotation, we modify a rudimentary computer vision algorithm designed for object detection in medical imaging to detect plume-like objects in gridded SO2 data. We then fit a solution to the general time-averaged dispersion of SO2 from a point source. We demonstrate these techniques using SO2 data generated by a newly developed probabilistic layer height and column loading algorithm designed for the Cross-track Infrared Sounder (CrIS), a hyperspectral infrared sensor aboard the Joint Polar Satellite System’s Suomi-NPP and NOAA-20 satellites. This SO2 data source is best suited to flux estimates at high-latitude volcanoes and at low-latitude, but high-altitude volcanoes. Of particular importance, IR SO2 data can fill an important data gap in the UV-based record: estimating SO2 emissions from high-latitude volcanoes through the polar winters when there is insufficient solar backscatter for UV sensors to be used.
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Weisman, R. Bruce, Tonya Cherukuri, Sergei M. Bachilo, Wei Meng, and Satish Nagarajaiah. "(Invited) Advanced Carbon Nanotube Fluorescence Spectrometry for Novel Applications." ECS Meeting Abstracts MA2023-01, no. 10 (August 28, 2023): 1181. http://dx.doi.org/10.1149/ma2023-01101181mtgabs.
Abstract:
Instrumental advances in near-IR fluorescence spectroscopy are enabling new types of measurements involving single-wall carbon nanotubes (SWCNTs). Two unique systems will be described. The first is a two-dimensional fluorescence-detected circular dichroism (FDCD) spectrometer. In this, SWCNT samples are excited by a spectrally selected supercontinuum laser beam that is switched between left- and right-circular polarization in an electro-optic modulator. Near-infrared sample fluorescence emitted in the backward direction is captured and directed to a scanning monochromator with a cooled InGaAs single-channel detector. After amplification and high precision digitization, the modulated signal component is extracted by computer-based phase sensitive detection. The system can measure a sample’s E22 circular dichroism in four spectral modes: 1) conventional FDCD, with scanned visible excitation wavelength and spectrally integrated (zero-order grating) emission detection; 2) Emission-specific FDCD, with scanned visible excitation wavelengths and selected emission wavelength; 3) Emission-scanned FDCD, with selected visible excitation wavelength and scanned emission wavelengths; 4) Excitation-Emission FDCD, with excitation and emission wavelengths both scanned to give two-dimensional data sets. This instrument can spectroscopically resolve enantiomer signals from a single (n,m) species in a racemic SWCNT sample. In a parallel project, developments in SWCNT fluorescence spectrometry are advancing nanotube-based strain measurement technology toward commercialization. Because SWCNT emission wavelengths vary systematically with axial strain, nanotubes in a thin coating on a specimen can serve as optically interrogated strain gauges. We apply this effect to measure strain maps through hyperspectral imaging of SWCNT fluorescence. A rotated band pass filter is used to capture a set of images in multiple spectral slices, from which a custom computer program deduces strain at each of ~105 image pixels and compiles strain maps. We will describe how this apparatus has evolved from a lab prototype into a compact portable system that can make measurements in industrial settings.
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Kharbach, Mourad, Mohammed Alaoui Mansouri, Mohammed Taabouz, and Huiwen Yu. "Current Application of Advancing Spectroscopy Techniques in Food Analysis: Data Handling with Chemometric Approaches." Foods 12, no. 14 (July 19, 2023): 2753. http://dx.doi.org/10.3390/foods12142753.
Abstract:
In today’s era of increased food consumption, consumers have become more demanding in terms of safety and the quality of products they consume. As a result, food authorities are closely monitoring the food industry to ensure that products meet the required standards of quality. The analysis of food properties encompasses various aspects, including chemical and physical descriptions, sensory assessments, authenticity, traceability, processing, crop production, storage conditions, and microbial and contaminant levels. Traditionally, the analysis of food properties has relied on conventional analytical techniques. However, these methods often involve destructive processes, which are laborious, time-consuming, expensive, and environmentally harmful. In contrast, advanced spectroscopic techniques offer a promising alternative. Spectroscopic methods such as hyperspectral and multispectral imaging, NMR, Raman, IR, UV, visible, fluorescence, and X-ray-based methods provide rapid, non-destructive, cost-effective, and environmentally friendly means of food analysis. Nevertheless, interpreting spectroscopy data, whether in the form of signals (fingerprints) or images, can be complex without the assistance of statistical and innovative chemometric approaches. These approaches involve various steps such as pre-processing, exploratory analysis, variable selection, regression, classification, and data integration. They are essential for extracting relevant information and effectively handling the complexity of spectroscopic data. This review aims to address, discuss, and examine recent studies on advanced spectroscopic techniques and chemometric tools in the context of food product applications and analysis trends. Furthermore, it focuses on the practical aspects of spectral data handling, model construction, data interpretation, and the general utilization of statistical and chemometric methods for both qualitative and quantitative analysis. By exploring the advancements in spectroscopic techniques and their integration with chemometric tools, this review provides valuable insights into the potential applications and future directions of these analytical approaches in the food industry. It emphasizes the importance of efficient data handling, model development, and practical implementation of statistical and chemometric methods in the field of food analysis.
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Cigna, Francesca, Deodato Tapete, and Zhong Lu. "Remote Sensing of Volcanic Processes and Risk." Remote Sensing 12, no. 16 (August 10, 2020): 2567. http://dx.doi.org/10.3390/rs12162567.
Abstract:
Remote sensing data and methods are increasingly being embedded into assessments of volcanic processes and risk. This happens thanks to their capability to provide a spectrum of observation and measurement opportunities to accurately sense the dynamics, magnitude, frequency, and impacts of volcanic activity in the ultraviolet (UV), visible (VIS), infrared (IR), and microwave domains. Launched in mid-2018, the Special Issue “Remote Sensing of Volcanic Processes and Risk” of Remote Sensing gathers 19 research papers on the use of satellite, aerial, and ground-based remote sensing to detect thermal features and anomalies, investigate lava and pyroclastic flows, predict the flow path of lahars, measure gas emissions and plumes, and estimate ground deformation. The strong multi-disciplinary character of the approaches employed for volcano monitoring and the combination of a variety of sensor types, platforms, and methods that come out from the papers testify the current scientific and technology trends toward multi-data and multi-sensor monitoring solutions. The research advances presented in the published papers are achieved thanks to a wealth of data including but not limited to the following: thermal IR from satellite missions (e.g., MODIS, VIIRS, AVHRR, Landsat-8, Sentinel-2, ASTER, TET-1) and ground-based stations (e.g., FLIR cameras); digital elevation/surface models from airborne sensors (e.g., Light Detection And Ranging (LiDAR), or 3D laser scans) and satellite imagery (e.g., tri-stereo Pléiades, SPOT-6/7, PlanetScope); airborne hyperspectral surveys; geophysics (e.g., ground-penetrating radar, electromagnetic induction, magnetic survey); ground-based acoustic infrasound; ground-based scanning UV spectrometers; and ground-based and satellite Synthetic Aperture Radar (SAR) imaging (e.g., TerraSAR-X, Sentinel-1, Radarsat-2). Data processing approaches and methods include change detection, offset tracking, Interferometric SAR (InSAR), photogrammetry, hotspots and anomalies detection, neural networks, numerical modeling, inversion modeling, wavelet transforms, and image segmentation. Some authors also share codes for automated data analysis and demonstrate methods for post-processing standard products that are made available for end users, and which are expected to stimulate the research community to exploit them in other volcanological application contexts. The geographic breath is global, with case studies in Chile, Peru, Ecuador, Guatemala, Mexico, Hawai’i, Alaska, Kamchatka, Japan, Indonesia, Vanuatu, Réunion Island, Ethiopia, Canary Islands, Greece, Italy, and Iceland. The added value of the published research lies on the demonstration of the benefits that these remote sensing technologies have brought to knowledge of volcanoes that pose risk to local communities; back-analysis and critical revision of recent volcanic eruptions and unrest periods; and improvement of modeling and prediction methods. Therefore, this Special Issue provides not only a collection of forefront research in remote sensing applied to volcanology, but also a selection of case studies proving the societal impact that this scientific discipline can potentially generate on volcanic hazard and risk management.
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Habart, E., T. Boutéraon, R. Brauer, N. Ysard, E. Pantin, A. Marchal, and A. P. Jones. "Spatial distribution of the aromatic and aliphatic carbonaceous nanograin features in the protoplanetary disk around HD 100546." Astronomy & Astrophysics 649 (May 2021): A84. http://dx.doi.org/10.1051/0004-6361/201936388.
Abstract:
Context. Carbonaceous nanograins are present at the surface of protoplanetary disks around Herbig Ae/Be stars, where most of the ultraviolet energy from the central star is dissipated. Efficiently coupled to the gas, they are unavoidable to understand the physics and chemistry of these disks. Furthermore, nanograins are able to trace the outer flaring parts of the disk and possibly the gaps from which the larger grains are missing. However, their evolution through the disks, from internal to external regions, is only poorly understood so far. Aims. Our aim is to examine the spatial distribution and evolution of the nanodust emission in the emblematic (pre-)transitional protoplanetary disk HD 100546. This disk shows many structures (annular gaps, rings, and spirals) and reveals very rich carbon nanodust spectroscopic signatures (aromatic, aliphatic) in a wide spatial range of the disk (~20−200 au). Methods. We analysed adaptive optics spectroscopic observations in the 3–4 μm range (angular resolution of ~0.1′′) and imaging and spectroscopic observations in the 8–12 μm range (angular resolution of ~0.3′′). The hyperspectral cube was decomposed into a sum of spatially coherent dust components using a Gaussian decomposition algorithm. We compared the data to model predictions using the heterogeneous dust evolution model for interstellar solids (THEMIS), which is integrated in the radiative transfer code POLARIS by calculating the thermal and stochastic heating of micro- and nanometre-sized dust grains for a given disk structure. Results. We find that the aromatic features at 3.3, 8.6, and 11.3 μm, and the aliphatic features between 3.4 and 3.5 μm are spatially extended; each band shows a specific morphology dependent on the local physical conditions. The aliphatic-to-aromatic band ratio, 3.4/3.3, increases with the distance from the star from ~0.2 (at 0.2′′ or 20 au) to ~0.45 (at 1′′ or 100 au), suggesting UV processing. In the 8–12 μm observed spectra, several features characteristic of aromatic particles and crystalline silicates are detected. Their relative contribution changes with the distance to the star. The model predicts that the features and adjacent continuum are due to different combinations of grain sub-populations, in most cases with a high dependence on the intensity of the UV field. The model reproduces the spatial emission profiles of the bands well, except for the inner 20-40 au, where the observed emission of the 3.3 and 3.4 μm bands is, unlike the predictions, flat and no longer increases with the UV field. Conclusions. With our approach that combines observational data in the near- to mid-IR and disk modelling, we deliver constraints on the spatial distribution of nano-dust particles as a function of the disk structure and radiation field.
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Kaestner, Bernd, Manuel Marschall, A. Hornemann, Selma Metzner, Piotr Patoka, Sofia Cortes, Gerd Wuebbeler, Arne Hoehl, Eckart Ruehl, and Clemens Elster. "Compressed AFM-IR hyperspectral nanoimaging." Measurement Science and Technology, September 21, 2023. http://dx.doi.org/10.1088/1361-6501/acfc27.
Abstract:
Abstract Infrared hyperspectral imaging is a powerful approach in the field of materials and life sciences. However, for the extension to modern sub-diffraction nanoimaging still remains a highly inefficient technique, as it acquires data via inherent sequential schemes. Here, we introduce the mathematical technique of low-rank matrix reconstruction to the sub-diffraction scheme of atomic force microscopy-based infrared spectroscopy (AFM-IR), for efficient hyperspectral infrared nanoimaging. To demonstrate its application potential, we chose the trypanosomatid unicellular parasites Leishmania species as a realistic target of biological importance. The mid-infrared spectral fingerprint window covering the spectral range from 1300 to 1900 cm-1 was chosen and a distance between the data points of 220 nm was used for nanoimaging of single parasites. The method of k-means cluster analysis was used for extracting the chemically distinct spatial locations. Subsequently, we randomly selected only 10% from an originally gathered data cube of 134 (x) × 50 (y) × 148 (spectral) AFM-IR measurements and completed the full data set by low-rank matrix reconstruction. This approach shows agreement in the cluster regions between full and reconstructed data cubes. Furthermore, we show that the results of the low-rank reconstruction are superior compared to alternative interpolation techniques in terms of error-metrics, cluster quality, and spectral interpretation for various subsampling ratios. We conclude that by using low-rank matrix reconstruction the data acquisition time can be reduced from more than 14 hours to 1 - 2 hours. These ndings can signi cantly boost the practical applicability of hyperspectral nanoimaging in both academic and industrial settings involving nano- and bio-materials.
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Azarfar, Ghazal, Ebrahim Aboualizadeh, Simona Ratti, Camilla Olivieri, Alessandra Norici, Michael J. Nasse, Mario Giordano, and Carol J. Hirschmugl. "Time lapse synchrotron IR chemical imaging for observing the acclimation of a single algal cell to CO2 treatment." Scientific Reports 11, no. 1 (June 24, 2021). http://dx.doi.org/10.1038/s41598-021-92657-3.
Abstract:
AbstractAlgae are the main primary producers in aquatic environments and therefore of fundamental importance for the global ecosystem. Mid-infrared (IR) microspectroscopy is a non-invasive tool that allows in principle studying chemical composition on a single-cell level. For a long time, however, mid-infrared (IR) imaging of living algal cells in an aqueous environment has been a challenge due to the strong IR absorption of water. In this study, we employed multi-beam synchrotron radiation to measure time-resolved IR hyperspectral images of individual Thalassiosira weissflogii cells in water in the course of acclimation to an abrupt change of CO2 availability (from 390 to 5000 ppm and vice versa) over 75 min. We used a previously developed algorithm to correct sinusoidal interference fringes from IR hyperspectral imaging data. After preprocessing and fringe correction of the hyperspectral data, principal component analysis (PCA) was performed to assess the spatial distribution of organic pools within the algal cells. Through the analysis of 200,000 spectra, we were able to identify compositional modifications associated with CO2 treatment. PCA revealed changes in the carbohydrate pool (1200–950 cm$$^{-1}$$ - 1 ), lipids (1740, 2852, 2922 cm$$^{-1}$$ - 1 ), and nucleic acid (1160 and 1201 cm$$^{-1}$$ - 1 ) as the major response of exposure to elevated CO2 concentrations. Our results show a local metabolism response to this external perturbation.
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Yin, Jiaze, Meng Zhang, Yuying Tan, Zhongyue Guo, Hongjian He, Lu Lan, and Ji-Xin Cheng. "Video-rate mid-infrared photothermal imaging by single-pulse photothermal detection per pixel." Science Advances 9, no. 24 (June 16, 2023). http://dx.doi.org/10.1126/sciadv.adg8814.
Abstract:
By optically sensing absorption-induced photothermal effect, mid-infrared (IR) photothermal (MIP) microscope enables super-resolution IR imaging of biological systems in water. However, the speed of current sample-scanning MIP system is limited to milliseconds per pixel, which is insufficient for capturing living dynamics. By detecting the transient photothermal signal induced by a single IR pulse through fast digitization, we report a laser-scanning MIP microscope that increases the imaging speed by three orders of magnitude. To realize single-pulse photothermal detection, we use synchronized galvo scanning of both mid-IR and probe beams to achieve an imaging line rate of more than 2 kilohertz. With video-rate speed, we observed the dynamics of various biomolecules in living organisms at multiple scales. Furthermore, by using hyperspectral imaging, we chemically dissected the layered ultrastructure of fungal cell wall. Last, with a uniform field of view more than 200 by 200 square micrometer, we mapped fat storage in free-moving Caenorhabditis elegans and live embryos.
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Kenkel, Seth, Mark Gryka, Lin Chen, Matthew P. Confer, Anirudha Rao, Scott Robinson, Kannanganattu V. Prasanth, and Rohit Bhargava. "Chemical imaging of cellular ultrastructure by null-deflection infrared spectroscopic measurements." Proceedings of the National Academy of Sciences 119, no. 47 (November 14, 2022). http://dx.doi.org/10.1073/pnas.2210516119.
Abstract:
Nearfield spectroscopic imaging techniques can be a powerful tool to map both cellular ultrastructure and molecular composition simultaneously but are currently limited in measurement capability. Resonance enhanced (RE) atomic force microscopy infrared (AFM-IR) spectroscopic imaging offers high-sensitivity measurements, for example, but probe-sample mechanical coupling, nonmolecular optical gradient forces, and noise overwhelm recorded chemical signals. Here, we analyze the key factors limiting AFM-IR measurements and propose an instrument design that enables high-sensitivity nanoscale IR imaging by combining null-deflection measurements with RE sensitivity. Our developed null-deflection scanning probe IR (NDIR) spectroscopic imaging provides ∼24× improvement in signal-to-noise ratio (SNR) compared with the state of the art, enables optimal signal recording by combining cantilever resonance with maximum laser power, and reduces background nonmolecular signals for improved analytical accuracy. We demonstrate the use of these properties for high-sensitivity, hyperspectral imaging of chemical domains in 100-nm-thick sections of cellular acini of a prototypical cancer model cell line, MCF-10A. NDIR chemical imaging enables facile recording of label-free, chemically accurate, high-SNR vibrational spectroscopic data from nanoscale domains, paving the path for routine studies of biomedical, forensic, and materials samples.