scholarly journals Investigation on the Absorption Bands Around 3.3 μm in CRISM Data

2021 ◽  
Author(s):  
Paola Manzari ◽  
Cosimo Marzo ◽  
Eleonora Ammannito
Keyword(s):  
Spectral Region ◽  
Confidence Limit ◽  
Limit Of Detection ◽  
Gaussian Model ◽  
Threshold Value ◽  
Absorption Bands ◽  
Gale Crater ◽  
Modified Gaussian Model ◽  
A Site ◽  
Lower Limits

Abstract While analyzing NIR-IR CRISM data on a site in Oxia Planum area, in the view of the ExoMars2022 mission, absorptions around 3.3 µm were noted in some pixel spectra. Absorptions in the range 3.1–3.6 mm are under the spotlight in planetary contexts since hydrocarbons molecules show bands in this range. Consequently, we started to search eventual hydrocarbon compounds on Mars surface, using CRISM data in the range 3.2–3.4 mm. To date, methane has been the unique hydrocarbon detected on Mars. Like other hydrocarbons, methane shows absorptions around 3.3 mm. Hence, we begun the investigation on CRISM data, on that locations where methane was detected and where it could form on the basis of the mineralogy of the specific site. The datasets chosen for this study include some sites of observations in Oxia Planum area, Gale Crater and Nili Fossae area. Beside the study of CRISM IR data, in the event that some observed absorptions were related to methane, we tried to calculate a theoretical lower limit of detection for each observation in CRISM data. This was performed using the Planetary Spectrum Generator, simulating the CRISM spectra of the different sites, with the diverse concentrations of CH4. These simulations served to establish the relation between concentration and methane band depths, as seen by CRISM spectrometer. Then, mapping the Modified Gaussian Model (MGM) fit on CRISM data, we extracted the band parameters of the absorptions in the 3.3 µm spectral region. Aside rare, suspected absorptions, an artifact was highlighted. Therefore, we took measures to avoid, as more as possible, this artifact from the interpretation of the 3.3 mm absorptions: distribution of clusters of pixels not vertically stacked and a rather conservative threshold on depth value. As result, we found interesting clusters of pixels which spectra overcome the imposed threshold. Furthermore, the threshold value varies from one observation to another, in a range between 0.0136–0.0237, that would correspond to a range of theoretical lower limits of concentration between 180 and 600 ppbv. Despite all the precautions, we consider that part of these absorptions could still be an artifact. Nevertheless, the aim of this paper is to show that CRISM data can show theoretically absorptions of hydrocarbons, and methane, in such quantities that in some observations are compatible with the order of the methane spikes effectively detected on Mars. Even if this work does not confirm nor deny the occurrences of methane seepages or hydrocarbons in the investigated images, it shows a possible method for searching hydrocarbons in CRISM data and for assessing a confidence limit in the detection methane band in CRISM data.

scholarly journals Investigation on the Absorption Bands Around 3.3 μm in CRISM Data

2020 ◽  
Author(s):  
Paola Manzari ◽  
Cosimo Marzo ◽  
Eleonora Ammannito
Keyword(s):  
Standard Deviation ◽  
Lower Limit ◽  
Gaussian Model ◽  
Depth Map ◽  
Threshold Value ◽  
Absorption Bands ◽  
Gale Crater ◽  
Methane Seepage ◽  
Modified Gaussian Model ◽  
A Site

Abstract Recently, the methane seepage detected by Mars Sample Laboratory (MSL) in the Gale crater area during 2013 was confirmed by methane detection by the Planetary Fourier Spectrometer (PFS). While analyzing NIR-IR CRISM data on a site in Oxia Planum area, in the view of a future comparison with data that will be collected by the Rosalind Franklin rover onboard the ExoMars2022 mission, a 3.3 μm absorption was noted in some pixel spectra. Since methane, like other hydrocarbons, shows absorptions in the range 3.1-3.6 μm, we begun to study this band in CRISM data to explore the possibility to look for seepages on Mars surface. The datasets chosen for this study, aside the site in Oxia Planum area, include some sites of observations on Gale Crater and other sites in Nili Fossae area. We used the Planetary Spectrum Generator to simulate CRISM spectra of the different sites, with the diverse concentrations of CH4 spikes. These simulations served to establish the relation between concentration and methane band depths, as seen by CRISM spectrometer. Then, mapping the Modified Gaussian Model fit on CRISM data, we extracted the band parameters of the absorptions in the 3.3 μm spectral region. Aside rare, suspected absorptions, an artifact was highlighted. Therefore, we have set a threshold on the depth to consider as depth of potential true absorptions, on the basis of the standard deviation (s) of absorption depth map. Finally, we concluded to favor as potential absorptions: distribution of clusters of pixels in the band mapping not vertically stacked and a threshold value >μ (average)+5σ (standard deviation) of the depth map. These threshold values set the lower limit for each observation on the methane concentration potentially detectable by CRISM. The threshold value varies from one observation to another, in a range between 0.0136-0.0237, that would correspond in a range of lower limit concentrations of 180 and 600 ppbv. We found interesting cluster of pixels which spectra overcome the imposed threshold. We still consider that part of them could still be a kind of unknown artifact. Nevertheless, the aim of this paper is to show that CRISM data can show potential absorptions of methane in such quantities that in some observations are compatible with the order of the methane spikes effectively detected in literature. Even if this work does not confirm nor deny the occurrences of methane seepages in the investigated images it shows a possible method for assessing a confidence limit in the detection of this band in CRISM data.

scholarly journals Extraction of aqueous minerals on Mars using CRISM based Targeted Reduced Data Records

2014 ◽  
Vol XL-8 ◽  
pp. 431-436 ◽  
Author(s):  
R. Gurunadham ◽  
S. Kumar
Keyword(s):  
Reflectance Spectrum ◽  
Gaussian Model ◽  
Wave Number ◽  
Imaging Spectrometer ◽  
Mineral Mapping ◽  
Gale Crater ◽  
Modified Gaussian Model ◽  
Shortwave Infrared ◽  
Reduced Data ◽  
Detection And Quantification

Many scientific studies have been carried out to extract the aqueous mineral signatures on the surface of Mars, which has a record of all minerals such as silicates form by magmatic processes and aqueous minerals in the presence of watery environment. To observe these watery conditions, a visible/shortwave infrared mineral mapping camera on Mars Reconnaissance Orbiter (MRO) called Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is used. The aim of this research is to extract the aqueous minerals on Mars using CRISM sensor. Gale Crater is selected for this study because of its past liquid water history.Gale is ~154 km in diameter and centered near 5.3&deg; S, 138&deg; E. Gale Crater has an interior mound named as "<i>Aeolis Mons</i>", which is nearly 100 km wide and 5 km high, consisting of layered sulfates and phyllosilicates. The CRISM reflectance (I/F) targeted reduced data records data of Gale crater, FRT000233AC, centred at 4&deg;25' S and 137&deg;20' E with high spatial (18 m, 35 m / pixel) and spectral resolution (362&ndash;1020 nm (VNIR), 1002&ndash;3920 nm (IR), 655 nm / channel) with 545 bands is acquired for this study. The detection and quantification of minerals has been carried out by using a model called modified Gaussian model (MGM). MGM is an approach that uses modified Gaussians in wave number space to model absorption shapes and fits them to a reflectance spectrum.

Liquid Chromatographic Analysis System for Cyclopiazonic Acid in Peanuts

1984 ◽  
Vol 67 (4) ◽  
pp. 728-731 ◽  
Author(s):  
John A Lansden
Keyword(s):  
Limit Of Detection ◽  
Gaussian Model ◽  
Cyclopiazonic Acid ◽  
Detector Response ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic Analysis ◽  
Modified Gaussian Model ◽  
Analysis System ◽  
Liquid Chromatographic ◽  
Exponentially Modified Gaussian

Abstract A liquid chromatographic procedure has been developed for analysis of cyclopiazonic acid in peanuts. The chromatographic system specifies a C18 or C8 column loaded with 4-dodecyldiethylenetriamine and an aqueous mobile phase containing 4-dodecyldiethylenetriamine, zinc acetate, ammonium acetate, 2-propanol, and acetonitrile. Cyclopiazonic acid was extracted from peanuts with methanol-chloroform (20 + 80), partitioned into aqueous sodium bicarbonate, acidified, and back-extracted into dichloromethane. The limit of detection (280 nm UV) was approximately 4 ng and detector response was linear to at least 1 μg pure cyclopiazonic acid. The recovery of cyclopiazonic acid from peanuts spiked at 68.9, 210, and 955 μ/kg was 85.9% (12.86% CV), 72.9% (6.43% CV), and 81.4% (0.40% CV), respectively. Calculation of the chromatographic peak parameters based on the exponentially modified Gaussian model indicated that the C18 column produced less peak skewing than did the C8 column.

First Nano-Infrared Spectroscopy and Imaging Measurements of Single Phospholipid Bilayers

2018 ◽  
Author(s):  
Adrian Cernescu ◽  
Michał Szuwarzyński ◽  
Urszula Kwolek ◽  
Karol Wolski ◽  
Paweł Wydro ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Ir Spectroscopy ◽  
Absorption Band ◽  
Spectral Region ◽  
Near Field ◽  
Phospholipid Bilayers ◽  
Model Systems ◽  
Absorption Bands ◽  
Protein Complement ◽  
20 Nm

<div><div>Scattering-mode Scanning Near-Field Optical Microscopy (sSNOM) allows one to obtain absorption spectra in the mid-IR region for samples as small as 20 nm in size. This configuration has made it possible to measure FTIR spectra of the protein complement of membranes. (Amenabar 2013) We now show that mid-IR sSNOM has the sensitivity required to measure spectra of phospholipids in individual bilayers in the spectral range 800 cm<sup>-1</sup>–1400 cm<sup>-1</sup>. We have observed the main absorption bands of the dipalmitoylphosphatidylcholine headgroups in this spectral region above noise level. We have also mapped the phosphate absorption band at 1070 cm<sup>-1</sup> simultaneously with the AFM topography. We have shown that we could achieve sufficient contrast to discriminate between single and multiple phospholipid bilayers and other structures, such as liposomes. This work opens the way to further research that uses nano-IR spectroscopy to describe the biochemistry of cell membranes and model systems.</div></div><div></div>

Lower Limits of Detection for Single Biological Particles Using Impedance Spectroscopy

2005 ◽  
Author(s):  
Pahnit Seriburi ◽  
Ashutosh Shastry ◽  
Angelique Van’t Wout ◽  
John Mittler ◽  
Shih-Hui Chao ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Impedance Spectroscopy ◽  
Minimally Invasive ◽  
Limit Of Detection ◽  
Single Cells ◽  
Lab On A Chip ◽  
Minimally Invasive Approach ◽  
Invasive Approach ◽  
Membrane Bound ◽  
Lower Limits

Single-cell impedance spectroscopy integrated with lab-on-a-chip systems provides a direct and minimally invasive approach for monitoring and characterizing properties of individual cells in real-time. Here we investigate the theoretical potential and limitations of this technique for analyzing single membrane-bound particles as small as 100 nm in diameter. Our theoretical model suggests a lower limit of detection for single cells on the order of a few microns.

scholarly journals THE PIGMENT-PROTEIN COMPOUND IN PHOTOSYNTHETIC BACTERIA

1940 ◽  
Vol 23 (4) ◽  
pp. 483-494 ◽  
Author(s):  
C. S. French
Keyword(s):  
Spectral Region ◽  
Photosynthetic Bacteria ◽  
Water Soluble ◽  
Absorption Curve ◽  
Absorption Bands ◽  
Soluble Cell

Absorption curves have been obtained in the spectral region of 450 to 900 mµ for the water soluble cell juice of four species of photosynthetic bacteria, Spirillum rubrum (strain S1), Rhodovibrio sp. (strain Gaffron), Phaeomonas sp. (strain Delft), and Streptococcus varians (strains C11 and orig.). These curves all show maxima at 790 and 590 mµ due to bacteriochlorophyll, whose highest band, however, occurs at 875, 855, or 840 mµ depending on the species. The bacteria that appear red rather than brown have a band at 550 mµ due to a carotinoid pigment. An absolute absorption curve of bacteriophaeophytin has maxima at 530 and 750 mµ. The extraction of cell juice by supersonic vibration does not change the position of the absorption bands or of the light absorbing capacity of the pigment.

Excitonic Bands in the Optical Absorption Spectra of A3MX6 and A3M2X9 (A = MeNH3, Me2NH2, Me3NH, Me4N; M = Bi, Sb; X = Cl, Br, I)

1994 ◽  
Vol 49 (6) ◽  
pp. 849-851 ◽  
Author(s):  
G. C. Papavassiliou ◽  
I. B. Koutselas
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Spectral Region ◽  
Visible Spectral Region ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Uv Visible ◽  
Low Dimensional

The title compounds (natural low-dimensional semiconductors) show strong excitonic optical absorption bands in the UV-visible spectral region, because of the dielectric confinement of excitons. as in the cases of other similar systems based on PbX2-4, SnX2-4. PtI - X - PtIV-X , Cdx,Sy-clusters etc

Assessment of landslide hazard under combined loading

2003 ◽  
Vol 40 (4) ◽  
pp. 821-829 ◽  
Author(s):  
Tien H Wu
Keyword(s):  
Pore Pressure ◽  
Failure Probability ◽  
Threshold Value ◽  
Landslide Hazard ◽  
Combined Loading ◽  
Rational Approach ◽  
Root Reinforcement ◽  
Load Combination ◽  
Time Period ◽  
A Site

A method for assessing landslide hazard under combined loading is described. The loads are considered as pulses that occur randomly in time. The method accounts for the rate of occurrence and the duration of the loads and calculates the rate of coincidence of two or more loads. This is used to calculate the failure probability, which is equal to the probability that the load combination will exceed a threshold value during a given time period. The method was applied to a site in the Cascade Mountains of Washington. The loads considered include those as a result of gravity, pore pressure from infiltration of rainfall plus snowmelt, loss of root reinforcement through fire or logging, and earthquakes. The example demonstrates a rational approach that accounts for the properties of the loads and the different loading conditions that may be expected.Key words: earthquake, failure probability, landslide hazard, load coincidence, load combination, pore pressure, root reinforcement.

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