scholarly journals Chemical separation of acrylic color components enabling the identification of the pigment spectroscopic response

2021 ◽  
Vol 136 (2) ◽  
Author(s):  
Dario Barni ◽  
Luisa Raimondo ◽  
Anna Galli ◽  
Rossella Yivlialin ◽  
Simone Caglio ◽  
...  
Keyword(s):  
Analytical Method ◽  
Diffuse Reflectance ◽  
Near Infrared ◽  
Chemical Properties ◽  
Chemical Separation ◽  
Spectroscopic Techniques ◽  
Characteristic Response ◽  
Color Components

AbstractAcrylic colors are mixtures of several components that can be identified as pigments, binders, and fillers, so that, when analyzed, the characteristic response of the different components may not be recognizable. This limits the accuracy of spectroscopic techniques, nonetheless particularly useful as they are noninvasive and can be applied in situ on real artworks. Here, a method is proposed to chemically separate and identify the different components of acrylic colors, in order to be able to study their spectroscopic response separately, in particular by ultraviolet–visible–near-infrared diffuse reflectance. The results clearly show that the chemical and analytical method developed here is fully reliable, with the advantage of clearly separating the response of the different components without any change of their chromatic/chemical properties. As a case study, the new method is applied here to original acrylic colors used by the Italian artist Ico Parisi, in view of building a spectra database.

scholarly journals Transformation and aging of biomass burning carbonaceous aerosol over tropical South America from aircraft in-situ measurements during SAMBBA

2019 ◽  
Author(s):  
William T. Morgan ◽  
James D. Allan ◽  
Stéphane Bauguitte ◽  
Eoghan Darbyshire ◽  
Michael J. Flynn ◽  
...  
Keyword(s):  
South America ◽  
Biomass Burning ◽  
Chemical Properties ◽  
Carbonaceous Aerosol ◽  
Air Masses ◽  
Atmospheric Aging ◽  
Primary Driver ◽  
Tropical South America

Abstract. We present a range of airborne in-situ observations of biomass burning carbonaceous aerosol over tropical South America, including a case study of a large tropical forest wildfire and a series of regional survey flights across the Brazilian Amazon and Cerrado. The study forms part of the South American Biomass Burning Analysis (SAMBBA) Project, which was conducted during September and October 2012. We find limited evidence for net increases in aerosol mass through atmospheric aging combined with substantial changes in the chemical properties of organic aerosol (OA). Oxidation of the OA increases significantly and rapidly on the scale of 2.5–3 hours based on our case study analysis and is consistent with secondary organic aerosol production. The observations of limited net enhancement in OA coupled with such changes in chemical composition, imply that evaporation of OA is also occurring to balance these changes. We observe significant coatings on black carbon particles at source, but with limited changes with aging in both particle core size and coating thickness. We quantify variability in the ratio of OA to carbon monoxide across our study as a key parameter representing both initial fire conditions and an indicator of net aerosol production with atmospheric aging. We observe ratios of 0.075–0.13 μg sm−3 ppbv−1 in the west of our study region over the Amazon tropical forest in air masses less influenced by precipitation and a value of 0.095 μg sm−3 ppbv−1 over the Cerrado environment in the east. Such values are consistent with emission factors used by numerical models to represent biomass burning OA emissions. Black carbon particle core sizes typically range from 250–290 nm, while coating thicknesses range from 40–110 nm in air masses less influenced by precipitation. The primary driver of the variability we observe appears to be related to changes at the initial fire source. A key lesson from our study is that the complex nature of the regional aerosol and its drivers precludes aggregating our observations as a function of atmospheric aging due to the many conflating and competing factors present. Our study explores and quantifies key uncertainties in the evolution of biomass burning aerosol at both nearfield and regional scales. Our results suggest that the initial conditions of the fire are the primary driver of carbonaceous aerosol physical and chemical properties over tropical South America, aside from significant oxidation of OA during atmospheric aging. Such findings imply that uncertainties in the magnitude of the aerosol burden and its impact on weather, climate, health and natural ecosystems most likely lie in quantifying emission sources, alongside atmospheric dispersion, transport and removal rather than chemical enhancements in mass.

scholarly journals Improving In-Situ Estimation of Soil Profile Properties Using a Multi-Sensor Probe

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1011 ◽  
Author(s):  
Xiaoshuai Pei ◽  
Kenneth Sudduth ◽  
Kristen Veum ◽  
Minzan Li
Keyword(s):  
Soil Properties ◽  
Soil Profile ◽  
Near Infrared ◽  
Diffuse Reflectance Spectroscopy ◽  
Chemical Properties ◽  
Estimation Accuracy ◽  
Soil Core ◽  
Least Squares Regression ◽  
Calibration Methods

Optical diffuse reflectance spectroscopy (DRS) has been used for estimating soil physical and chemical properties in the laboratory. In-situ DRS measurements offer the potential for rapid, reliable, non-destructive, and low cost measurement of soil properties in the field. In this study, conducted on two central Missouri fields in 2016, a commercial soil profile instrument, the Veris P4000, acquired visible and near-infrared (VNIR) spectra (343–2222 nm), apparent electrical conductivity (ECa), cone index (CI) penetrometer readings, and depth data, simultaneously to a 1 m depth using a vertical probe. Simultaneously, soil core samples were obtained and soil properties were measured in the laboratory. Soil properties were estimated using VNIR spectra alone and in combination with depth, ECa, and CI (DECS). Estimated soil properties included soil organic carbon (SOC), total nitrogen (TN), moisture, soil texture (clay, silt, and sand), cation exchange capacity (CEC), calcium (Ca), magnesium (Mg), potassium (K), and pH. Multiple preprocessing techniques and calibration methods were applied to the spectral data and evaluated. Calibration methods included partial least squares regression (PLSR), neural networks, regression trees, and random forests. For most soil properties, the best model performance was obtained with the combination of preprocessing with a Gaussian smoothing filter and analysis by PLSR. In addition, DECS improved estimation of silt, sand, CEC, Ca, and Mg over VNIR spectra alone; however, the improvement was more than 5% only for Ca. Finally, differences in estimation accuracy were observed between the two fields despite them having similar soils, with one field demonstrating better results for all soil properties except silt. Overall, this study demonstrates the potential for in-situ estimation of profile soil properties using a multi-sensor approach, and provides suggestions regarding the best combination of sensors, preprocessing, and modeling techniques for in-situ estimation of profile soil properties.

In situ target enzyme-activated near-infrared fluorescent probe: A case study of CYP2J2 using three-fragmentary molecular assembly engineering

2021 ◽  
Vol 328 ◽  
pp. 129034 ◽  
Author(s):  
Yanpeng Dai ◽  
Tianzi Xue ◽  
Hefang Ji ◽  
Pan Zhang ◽  
Dongdong Zhang ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Near Infrared ◽  
Molecular Assembly ◽  
Target Enzyme

scholarly journals Performance of Fluorescence and Diffuse Reflectance Hyperspectral Imaging for Characterization of Lutefisk: A Traditional Norwegian Fish Dish

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1191 ◽  
Author(s):  
Abdo Hassoun ◽  
Karsten Heia ◽  
Stein-Kato Lindberg ◽  
Heidi Nilsen
Keyword(s):  
Hyperspectral Imaging ◽  
High Performance ◽  
Diffuse Reflectance ◽  
Near Infrared ◽  
Diffuse Reflectance Spectroscopy ◽  
Ph Value ◽  
Raw Materials ◽  
Industrial Applications ◽  
Spectroscopic Techniques

Lutefisk is a traditional Norwegian fish dish made from dried fish, such as cod or other whitefish. In Norway and other Nordic countries, lutefisk is considered among the most popular dishes served during Christmas or other festive occasions. However, to date, little attention has been paid to this product, and available research on the quality, processing, and chemistry of lutefisk is still limited. The quality of this very delicate product, with a high pH value, depends on many factors, such as the initial quality of raw materials (stockfish), the quantity of lye used during the preparation process of lutefisk, and time during soaking in the lye and water, among others, making it challenging to both optimize processing and monitor the quality of lutefisk. In this study, four commercially available lutefisk brands (labelled as A, B, C, and D) were characterized using two online spectroscopic techniques, namely fluorescence and diffuse reflectance hyperspectral imaging, implemented on conveyor belts to mimic industrial applications. The samples were also analyzed by the use of an offline laboratory instrument based on visible/near infrared diffuse reflectance spectroscopy. Three traditional measurements, including texture, water content, and pH, were also conducted on the same samples. Supervised classification PLS-DA models were built with each dataset and relationships between the spectroscopic measurements and the traditional data were investigated using canonical correlations. The spectroscopic methods, especially fluorescence spectroscopy, demonstrated high performance for the discrimination between samples of the different brands, with high correlations between the spectral and traditional measurements. Although more validations of the results of this study are still required, these preliminary findings suggest that the destructive, laborious, and time-consuming traditional techniques can be replaced by rapid and nondestructive online measurements based on hyperspectral imaging used in fluorescence or diffuse reflectance mode.

Intensity-Value Corrections for Integrating Sphere Measurements of Solid Samples Measured behind Glass

2014 ◽  
Vol 68 (11) ◽  
pp. 1224-1234 ◽  
Author(s):  
Timothy J. Johnson ◽  
Bruce E. Bernacki ◽  
Rebecca L. Redding ◽  
Yin-Fong Su ◽  
Carolyn S. Brauer ◽  
...  
Keyword(s):  
Diffuse Reflectance ◽  
Near Infrared ◽  
Polished Glass ◽  
Reflectance Spectra ◽  
Integrating Sphere ◽  
Empirical Correction ◽  
Hemispherical Reflectance ◽  
Infrared Spectral ◽  
Reflecting Surfaces

Accurate and calibrated directional-hemispherical reflectance spectra of solids are important for both in situ and remote sensing. Many solids are in the form of powders or granules and to measure their diffuse reflectance spectra in the laboratory, it is often necessary to place the samples behind a transparent medium such as glass for the ultraviolet (UV), visible, or near-infrared spectral regions. Using both experimental methods and a simple optical model, we demonstrate that glass (fused quartz in our case) leads to artifacts in the reflectance values. We report our observations that the measured reflectance values, for both hemispherical and diffuse reflectance, are distorted by the additional reflections arising at the air–quartz and sample–quartz interfaces. The values are dependent on the sample reflectance and are offset in intensity in the hemispherical case, leading to measured values up to ∼6% too high for a 2% reflectance surface, ∼3.8% too high for 10% reflecting surfaces, approximately correct for 40–60% diffuse-reflecting surfaces, and ∼1.5% too low for 99% reflecting Spectralon® surfaces. For the case of diffuse-only reflectance, the measured values are uniformly too low due to the polished glass, with differences of nearly 6% for a 99% reflecting matte surface. The deviations arise from the added reflections from the quartz surfaces, as verified by both theory and experiment, and depend on sphere design. Empirical correction factors were implemented into post-processing software to redress the artifact for hemispherical and diffuse reflectance data across the 300–2300 nm range.

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