scholarly journals Detection of Microplastics in Water and Ice

2021 ◽  
Vol 13 (17) ◽  
pp. 3532
Author(s):  
Seohyun Jang ◽  
Joo-Hyung Kim ◽  
Jihyun Kim
Keyword(s):  
Convex Hull ◽  
Spectral Region ◽  
Spectral Properties ◽  
Chemical Compositions ◽  
Reflection Spectra ◽  
Mathematical Methods ◽  
Gaussian Peak ◽  
Low Intensity ◽  
Large Maximum ◽  
Meaningful Measure

It is possible to detect various microplastics (MPs) floating on water or contained in ice due to the unique optical characteristics of plastics of various chemical compositions and structures. When the MPs are measured in the spectral region between 800 and 1000 nm, which has relatively little influence on the temperature change in water, they are frequently perceived as noise or obscured by the surrounding reflection spectra because of the small number and low intensity of the representative peak wavelengths. In this study, we have applied several mathematical methods, including the convex hull, Gaussian deconvolution, and curve fitting to amplify and normalize the reflectance and thereby find the spectral properties of each polymer, namely polypropylene (PP), polyethylene terephthalate (PET), methyl methacrylate (PMMA), and polyethylene (PE). Blunt-shaped spectra with a relatively large maximum of normalized reflectance (NRmax) can be decomposed into several Gaussian peak wavelengths: 889, 910, and 932 nm for the PP and 898 and 931 nm for the PE. Moreover, unique peak wavelengths with the meaningful measure at 868 and 907 nm for the PET and 887 nm for the PMMA were also obtained. Based on the results of the study, one can say that each plastic can be identified with up to 81% precision by compensating based on the spectral properties even when they are hidden in water or ice.

scholarly journals Surface Plasmon Resonances in Sn: In2O3 Thin Films with Diffraction Grating

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1034
Author(s):  
Noriyuki Hasuike ◽  
Saito Ochiai ◽  
Ryotaro Iwakiri ◽  
Minoru Takeda ◽  
Woo Sik Yoo ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Spectral Region ◽  
Diffraction Grating ◽  
Near Infrared ◽  
Transparent Conductive Oxide ◽  
Infrared Region ◽  
Reflection Spectra ◽  
Surface Plasmon Resonances ◽  
Infrared Spectral Region ◽  
Infrared Spectral

We newly proposed transparent conductive oxide with diffraction grating structure as an excitation field of surface plasmon resonance working at near-infrared spectral region. We experimentally demonstrated the excitation of SPR using Sn-doped In2O3 films with micro-meter pitched diffraction grating. In this study, we considered the correlation between the grating pitch and the optical reflection spectra. Reflection spectra showed clear polarization properties in infrared spectral region, and the reflection edge has also correlation with the pitch of grating. From these results, the excitation of SPR grating was successfully demonstrated and the wavelength can be tuned by changing the grating pitch in infrared region.

Two Dimensional Photonic Crystal Modes and Resonances in Three-dimensional Structures

2001 ◽  
Vol 694 ◽  
Author(s):  
Shanhui Fan ◽  
J. D. Joannopoulos
Keyword(s):  
Spectral Properties ◽  
Three Dimensional ◽  
Reflection Spectra ◽  
Two Dimensional ◽  
Quality Factors ◽  
Transmission And Reflection Spectra ◽  
General Physical ◽  
Two Dimensional Photonic Crystal ◽  
Index Modulation ◽  
Transmission And Reflection

AbstractWe present three-dimensional analysis of two-dimensional guided resonances in photonic crystalslab structures. This analysis leads to a new understanding of the complex spectral properties of such systems. Specifically, we calculate the dispersion diagrams, the modal patterns, and transmission and reflection spectra of these resonances. From these calculations, a key observation emerges involving the presence of two temporal pathways for transmission and eflection processes. Using this insight, we introduce a general physical model that explains the essential features of complex spectral properties. Finally, we show that the quality factors of these resonances are strongly influenced by the symmetry of the modes, and the strength ofthe index modulation.

scholarly journals А METHOD OF EVALUATING THE ABSORPTION SPECTRUM OF WHEAT LEAF BY THE SPECTRUM OF DIFFUSE REFLECTION

2019 ◽  
Vol 48 (5) ◽  
pp. 68-76
Author(s):  
S. V. Nikolaev ◽  
E. A. Urbanovich ◽  
V. R. Shayapov ◽  
E. A. Orlova ◽  
D. A. Afonnikov
Keyword(s):  
Absorption Spectrum ◽  
Diffusion Coefficient ◽  
Absorption Coefficient ◽  
Diffuse Reflection ◽  
Disperse Medium ◽  
Normal Growth ◽  
Propagation Model ◽  
Reflection Spectra ◽  
Mathematical Methods ◽  
Wheat Leaf

Spectral analysis methods are widely used to assess the condition of plants during normal growth and the development of infections. In combination with mathematical methods of pattern recognition from reflection spectra, different indices are constructed, which vary for plants in different studied physiological (and pathophysiological) states. This approach involves setting up indices for specific shared states. Information about the content of pigments is more universal, and allows to talk about the state of the plant on the basis of physiological concepts, regardless of the task being solved. Methods of reflective spectroscopy have recently been developed to obtain information about the content of pigments. The absorption spectrum is estimated from the diffuse reflection spectrum based on the light propagation model in a disperse medium. One of the models of this type is the model Kubelka-Munch. In the case of the large optical thickness of the sample, when the flow passing through the sample at the output is almost zero, one can use a simplified formula, which does not include the thickness of the sample. In other cases, it is necessary to measure this thickness, which is problematic for such biological objects as a plant leaf, because of the complex relief of the leaf surface. The article presents the measurement method and results of studying the applicability of the formula Kubelka-Munch for obtaining absorption spectra from reflection spectra of a wheat leaf without measuring its thickness. The formula is derived for calculation of Kubelka-Munch function (ratio of the absorption coefficient to the diffusion coefficient) by two measurements of diffusion scattering coefficients from the sample, which are performed with absorbing and reflecting substrates. The method allows to calculate the ratio of the absorption coefficient to the diffusion coefficient without measuring the thickness of the sample under study. This index can be used as an assessment criteria of the absorption spectrum with some proportionality factor. It is possible to recommend the method described as the most valid and accurate one for the determination of the absorption coefficient to the diffusion coefficient ratio of a leaf in the laboratory conditions.

Spectral properties of zeromethinemerocyanines

1979 ◽  
Vol 44 (5) ◽  
pp. 1413-1422
Author(s):  
Jaroslava Vávrová ◽  
Miloš Vávra ◽  
Zdeněk Babák
Keyword(s):  
Ir Spectra ◽  
Spectral Region ◽  
Spectral Properties ◽  
Silver Halide ◽  
Visible Spectral Region ◽  
Ethanolic Solution

Twenty six zeromethinemerocyanine dyes III were prepared by condensation of carbonylmethylene group containing heterocycles II with nitrogen-containing 2-alkylmercapto heterocycles I. Their absorption maxima in the visible spectral region in ethanolic solution, as well as of the dyes adsorbed on silver halide, were measured. IR spectra in chloroform and in KBr were also studied.

Some Irradiation Effects in Nonmetallic Crystals

1959 ◽  
Vol 3 ◽  
pp. 269-288 ◽  
Author(s):  
M.C. Wittels ◽  
F.A. Sherrill
Keyword(s):  
Special Technique ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Irradiation Effects ◽  
Radioactive Materials ◽  
X Ray ◽  
Oak Ridge ◽  
Low Intensity ◽  
Fission Spectrum ◽  
Test Reactor

AbstractNonmetallic crystals with a variety of structures and chemical compositions have been exposed to fission spectrum neutrons in a core position of the Low Intensity Test Reactor (LITR), Oak Ridge, and examined by X-ray diffraction techniques. Wherever possible, single crystals were employed, and the neutron dosages ranged between 1019 and 1021 neutrons/cm2 at a temperature of approximately 85°C. In no case was a special technique used for examining radioactive materials because the problem of heavy induced radioactivity was greatly reduced by working withcrystals weighing a milligram or less. Both film and counter measurements were employed.

scholarly journals Spectral properties and detectability of supermassive stars in protoglobular clusters at high redshift

2019 ◽  
Vol 633 ◽  
pp. A9 ◽  
Author(s):  
F. Martins ◽  
D. Schaerer ◽  
L. Haemmerlé ◽  
C. Charbonnel
Keyword(s):  
Effective Temperature ◽  
Spectral Properties ◽  
Globular Clusters ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Chemical Compositions ◽  
Deep Imaging ◽  
Balmer Lines ◽  
Hydrogen Lines

Context. Globular clusters (GCs) contain multiple stellar populations with peculiar chemical compositions. Pollution of the intracluster gas by an early population of fast-evolving stars is the most common scenario for explaining the observations. Stars with masses in excess of 1000 M⊙ have recently been suggested as potential polluters. Aims. We investigate the spectral properties of proto-GCs that would host a supermassive star (SMS). Our main goal is to quantify how such a star would affect the integrated light of the cluster, and to study the detectability of such objects. Methods. We computed nonlocal thermal equilibirum atmosphere models for SMS with various combinations of stellar parameters (luminosity, effective temperature, and mass) and metallicities appropriate for GCs, and we predict their emergent spectra. Using these spectra, we calculated the total emission of young proto-GCs with SMS as predicted in a previously reported scenario, and we computed synthetic photometry in UV, optical, and near-IR bands, in particular for the James Webb Space Telescope (JWST). Results. At an effective temperature of 10 000 K, the spectrum of SMSs shows a Balmer break in emission. This feature is due to strong nonlocal thermal equilibrium effects (implied by the high luminosity) and is not observed in “normal” stars. The hydrogen lines also show a peculiar behavior, with Balmer lines in emission while higher series lines are in absorption. At 7000 K, the Balmer break shows a strong absorption. At high effective temperatures, the Lyman break is found in emission. Cool and luminous SMSs are found to dominate the integrated spectrum of the cluster, except for the UV range. The predicted magnitudes of these proto-GCs are magAB ∼ 28 − 30 between 0.7 and 8 μm and for redshifts z ∼ 4 − 10, which is detectable with the JWST. The peculiar observational features of cool SMSs imply that they might in principle be detected in color-color diagrams that probe the spectral energy distribution below and above the Balmer break. Conclusions. Our results show that SMSs should be detectable in proto-GCs if they are luminous and relatively cool. They may be found through deep imaging with the JWST.

Comparison of spectral properties of three hyperspectral imaging (HSI) sensors in evaluating main chemical compositions of cured pork

2019 ◽  
Vol 261 ◽  
pp. 100-108 ◽  
Author(s):  
Ji Ma ◽  
Da-Wen Sun ◽  
Bart Nicolai ◽  
Hongbin Pu ◽  
Pieter Verboven ◽  
...  
Keyword(s):  
Hyperspectral Imaging ◽  
Spectral Properties ◽  
Chemical Compositions

Das Fluoreszenzspektrum von Anthracen-Kristallen

1969 ◽  
Vol 24 (6) ◽  
pp. 943-951 ◽  
Author(s):  
E. Glöckner ◽  
H. C. Wolf
Keyword(s):  
Band Structure ◽  
Spectral Region ◽  
Emission Lines ◽  
Exciton Band ◽  
Lower Edge ◽  
Polarization Ratio ◽  
Temperature Dependent ◽  
Low Intensity ◽  
Living State ◽  
Good Agreement

The fluorescence spectrum of extremely purified and good anthracene crystals has been re­measured. It is compared with the exciton band structure as calculated by Davydov and Sheka. The origin of the intrinsic fluorescence is at 25 097 cm-1. This is the lower edge of the exciton band with k ≠ 0. Therefore this 0.0-transition is forbidden. The allowed 0.0.transition of the lower Davydov component of the exciton band is observed at 25 298 cm-1 with very low intensity. This is the position of the very short living state k = Q (Q=photon wave vector) in the exciton band. Further observations concerning the structure and temperature dependent width of emission lines, the nature of exciton-phonon and exciton-vibron coupling and the large band width in absorption are also in good agreement with the calculated band structure.The polarization ratio of the strongest vibronic transitions is 7.5 ± 1 good agreement with the oriented gas model. The spectral region near the forbidden 0.0-transition is completely 6-polarized. Effects of defects in the spectrum (series of lines due to impurities and X-traps, continuous back­ground) were widely eliminated. They are discussed here only as far as necessary for a better understanding of the unperturbed crystal spectrum. In an appendix a list of 154 fluorescence lines is given.

Sign in / Sign up

Export Citation Format

Share Document