scholarly journals Vibrational spectroscopic analyses of unique yellow feather pigments (spheniscins) in penguins

2013 ◽  
Vol 10 (83) ◽  
pp. 20121065 ◽  
Author(s):  
Daniel B. Thomas ◽  
Cushla M. McGoverin ◽  
Kevin J. McGraw ◽  
Helen F. James ◽  
Odile Madden
Keyword(s):  
Visible Spectrum ◽  
Heterocyclic Ring ◽  
Yellow Colour ◽  
Spectral Bands ◽  
Colour Palette ◽  
Macaroni Penguin ◽  
Stem Lineage ◽  
Non Destructive ◽  
Avian Family ◽  
Aromatic Heterocyclic

Many animals extract, synthesize and refine chemicals for colour display, where a range of compounds and structures can produce a diverse colour palette. Feather colours, for example, span the visible spectrum and mostly result from pigments in five chemical classes (carotenoids, melanins, porphyrins, psittacofulvins and metal oxides). However, the pigment that generates the yellow colour of penguin feathers appears to represent a sixth, poorly characterized class of feather pigments. This pigment class, here termed ‘spheniscin’, is displayed by half of the living penguin genera; the larger and richer colour displays of the pigment are highly attractive. Using Raman and mid-infrared spectroscopies, we analysed yellow feathers from two penguin species (king penguin, Aptenodytes patagonicus ; macaroni penguin, Eudyptes chrysolophus ) to further characterize spheniscin pigments. The Raman spectrum of spheniscin is distinct from spectra of other feather pigments and exhibits 17 distinctive spectral bands between 300 and 1700 cm −1 . Spectral bands from the yellow pigment are assigned to aromatically bound carbon atoms, and to skeletal modes in an aromatic, heterocyclic ring. It has been suggested that the penguin pigment is a pterin compound; Raman spectra from yellow penguin feathers are broadly consistent with previously reported pterin spectra, although we have not matched it to any known compound. Raman spectroscopy can provide a rapid and non-destructive method for surveying the distribution of different classes of feather pigments in the avian family tree, and for correlating the chemistry of spheniscin with compounds analysed elsewhere. We suggest that the sixth class of feather pigments may have evolved in a stem-lineage penguin and endowed modern penguins with a costly plumage trait that appears to be chemically unique among birds.

scholarly journals Bicyclic 1,3a,6a-Triazapentalene Chromophores: Synthesis, Spectroscopy and Their Use as Fluorescent Sensors and Probes

Chemosensors ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 16
Author(s):  
Yingchun Wang ◽  
Tomas Opsomer ◽  
Wim Dehaen
Keyword(s):  
Stokes Shift ◽  
Substituent Effects ◽  
Visible Spectrum ◽  
Fluorescent Sensors ◽  
Biological Imaging ◽  
Fluorescent Imaging ◽  
Fluorescence Properties ◽  
Imaging Probes ◽  
Synthetic Methodologies ◽  
Aromatic Heterocyclic

The 1,3a,6a-triazapentalene (TAP) is an aromatic heterocyclic fluorescent dye with interesting features such as its small size, large Stokes shift, solvatochromism, and emission wavelengths that are spread across the visible spectrum. TAPs have been synthesized via different synthetic strategies involving click−cyclization−aromatization domino reactions, gold-catalyzed cyclization of propargyl triazoles or triazolization of acetophenones. As a result, TAPs with diverse substitution patterns were obtained, showing varying fluorescence properties. Based on these properties, several TAPs have been selected and studied as fluorescent imaging probes in living cells and as sensors. This mini review provides an overview of the research on the bicyclic TAPs and does not comment on the literature about benzo or otherwise fused systems. The synthetic methodologies for the preparation of TAPs, the substituent effects on the fluorescence properties, and the behavior of the TAP core as an element of biological imaging probes and sensors are discussed.

scholarly journals Hyperspectral Imaging for Bloodstain Identification

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3045
Author(s):  
Maheen Zulfiqar ◽  
Muhammad Ahmad ◽  
Ahmed Sohaib ◽  
Manuel Mazzara ◽  
Salvatore Distefano
Keyword(s):  
Hyperspectral Imaging ◽  
Dna Analysis ◽  
Forensic Sciences ◽  
Blood Protein ◽  
Chemical Methods ◽  
Acrylic Paint ◽  
Spectral Bands ◽  
Nail Polish ◽  
Spatial Dimensions ◽  
Non Destructive

Blood is key evidence to reconstruct crime scenes in forensic sciences. Blood identification can help to confirm a suspect, and for that reason, several chemical methods are used to reconstruct the crime scene however, these methods can affect subsequent DNA analysis. Therefore, this study presents a non-destructive method for bloodstain identification using Hyperspectral Imaging (HSI, 397–1000 nm range). The proposed method is based on the visualization of heme-components bands in the 500–700 nm spectral range. For experimental and validation purposes, a total of 225 blood (different donors) and non-blood (protein-based ketchup, rust acrylic paint, red acrylic paint, brown acrylic paint, red nail polish, rust nail polish, fake blood, and red ink) samples (HSI cubes, each cube is of size 1000 × 512 × 224, in which 1000 × 512 are the spatial dimensions and 224 spectral bands) were deposited on three substrates (white cotton fabric, white tile, and PVC wall sheet). The samples are imaged for up to three days to include aging. Savitzky Golay filtering has been used to highlight the subtle bands of all samples, particularly the aged ones. Based on the derivative spectrum, important spectral bands were selected to train five different classifiers (SVM, ANN, KNN, Random Forest, and Decision Tree). The comparative analysis reveals that the proposed method outperformed several state-of-the-art methods.

A Synthesis of 1,2,4-Triazolo[1,5-f]phenanthridines by Rearrangements of 1,2,5-Oxadiazoles Involving an NCN Sequence with the Imine Nitrogen in an Aromatic Heterocyclic Ring

Heterocycles ◽  
1990 ◽  
Vol 31 (5) ◽  
pp. 869 ◽  
Author(s):  
Giuseppe Cusmano ◽  
Gabriella Macaluso ◽  
Michelangelo Gruttadauria ◽  
Silvestre Buscemi
Keyword(s):  
Heterocyclic Ring ◽  
Imine Nitrogen ◽  
Aromatic Heterocyclic

Mixed alkoxy/hydroxy 1,8-naphthalimides: expanded fluorescence colour palette and in vitro bioactivity

2020 ◽  
Vol 56 (50) ◽  
pp. 6866-6869
Author(s):  
Elley E. Rudebeck ◽  
Rosalind P. Cox ◽  
Toby D. M. Bell ◽  
Rameshwor Acharya ◽  
Zikai Feng ◽  
...  
Keyword(s):  
Functional Group ◽  
Visible Spectrum ◽  
In Vitro Bioactivity ◽  
Colour Palette

An efficient and functional group tolerant route to access hydroxy 1,8-naphthalimides has been used to synthesise a range of mono- and disubstituted hydroxy-1,8-naphthalimides with fluorescence emissions covering the visible spectrum.

The Optical Properties of Plasma-Deposited SiO2 and Si3N4 Bragg Reflectors in the Spectral Range from 1.8 to 3.0 eV

1992 ◽  
Vol 281 ◽  
Author(s):  
D. J. Stephens ◽  
S. S. He ◽  
G. Lucovsky ◽  
H. Mkkelsen ◽  
K. Leo ◽  
...  
Keyword(s):  
Optical Properties ◽  
Periodic Structures ◽  
Spectral Response ◽  
Chemical Vapor ◽  
Visible Spectrum ◽  
Bragg Reflectors ◽  
Spectral Bands ◽  
Entire Visible Spectrum ◽  
Optical Behavior ◽  
Constituent Layer

ABSTRACTWe have prepared 19-layer Si3N4:SiO2/…‥Si3N4:SiO2/Si3N4 (HL/HL/…HL/H), Bragg reflectors by remote plasma-enhanced chemical-vapor deposition, and have adjusted the constituent layer thicknesses to generate highly reflecting films over the entire visible spectrum from approximately 1.8 eV (∼690 nm) to 3.0 eV (∼410 nm). Peak values of the reflectance, in spectral bands with half-widths of ∼0.4 to 0.5 eV, are in the range of 96 to 98 %. The spectral response functions of these stacks exhibit departures from the optical behavior as calculated for exactly periodic structures with λ/4 layer thicknesses, and can be accounted for by taking into account: i) dispersion and absorption in the optical properties of the constituent layers; and ii) departures from the idealized and constant layer thicknessses.

Non-Destructive Electro- and Photo-Luminescence Imaging of Dislocations in SiC Epitaxy

2006 ◽  
Vol 911 ◽  
Author(s):  
Kendrick Liu ◽  
Robert E Stahlbush ◽  
Joshua D Caldwell ◽  
Karl D Hobart ◽  
Francis J Kub ◽  
...  
Keyword(s):  
Basal Plane ◽  
Image Features ◽  
Device Fabrication ◽  
Spectral Information ◽  
Objective Lens ◽  
Epitaxial Layers ◽  
Anode Layer ◽  
Substrate Interface ◽  
Spectral Bands ◽  
Non Destructive

AbstractElectroluminescence (EL) and photoluminescence (PL) imaging and stressing techniques are presented that are useful characterization tools for SiC epitaxial layers grown for power devices. Both EL and PL techniques are non-destructive, and the PL imaging is non-contact. These features are important for qualifying epitaxial layers before subjecting the layers to the time-consuming and costly process of device fabrication. By imaging at various emission spectral bands, the spectral information are correlated to the geometric features in the images. This correlation enables the differentiation of dissimilar defects having similar geometric shapes. Row average plots of images at various emission spectral bands revealed that threading dislocations (TDs) have strong emission above 900 nm and that basal plane dislocations (BPDs) have a broad spectral emission that are most easily distinguished in the range between 738 nm and 870 nm. The correlation between spectral information and the image features clearly distinguished TDs and BPDs from other defects, such as, organic substance and other surface blemishes. In addition to identifying the defects, understanding their origin can be useful in developing low-defect growth techniques. The defect origination depth is one of the important information for understanding defect origin. Two schemes for determining the defect origination depth are presented. Varying the focus depth by adjusting the objective lens height is a crude but quick scheme. Stressing the epilayer to grow the BPDs till they reach the surface or the epilayer/substrate interface is more time-consuming but more accurate. The scheme of varying the focus was demonstrated using PL imaging on a 50-mm thick n- epilayer with no p+ anode layer. Adjusting the focus on a partial dislocation in the n- epilayer revealed segments of the partial coming more in focus near the epilayer/substrate interface, suggesting the defect origination depth was at or near the interface. The stress and growth scheme was demonstrated on a straight string of half loop defects in a 100-mm thick n- epilayer. During electrical stressing, BPDs emanated from the half loops and eventually propagated to the surface at a lateral distance of 250 mm. With the basal plane at an 8° offcut from the surface, the origin of the BPDs was calculated to be 35 mm below the surface, suggesting the defects to be introduced during the growth process. Either EL or PL technique can be used with any of these two schemes to determine the defect origination depth. However, the PL technique has the benefit that the p+ anode layer and the procedure for forming a metal grid are not required.

scholarly journals Disentangling the Relationship in Health of Zea Mays Crop using Photochemical Reflectance Index and Nitrogen Reflectance Index

2020 ◽  
Vol 9 (4) ◽  
pp. 2646-2649
Keyword(s):  
Zea Mays ◽  
Standard Error ◽  
Growing Season ◽  
Stress Factors ◽  
P Value ◽  
Spectral Absorption ◽  
Photochemical Reflectance Index ◽  
Spectral Bands ◽  
The Relationship ◽  
Non Destructive

Determining the spatial variation of different plant factors throughout growing season will help to resolve stress factors within a field in a timely basis. Whereas the spectral characterizes help to estimate the proper photosynthesis process. This research shows that the nitrogen reflectance index (NRI) help to predict the nitrogen level of healthy and diseased plants and photochemical reflectance index (PRI) affects the leaf spectral absorption. These indices are calibrated under the hyperspectral pushbroom camera Resonon PIKA-L (400-1000nm) which is non-destructive and less time consuming, it is available in RUSA lab in Dr. Babasaheb Ambedkar Marathawada University, Aurangabad, Maharashtra. The spectral bands considered for the calculation of NRI are 700nm, 670nm, 570nm and for PRI spectral bands considered were 531nm, 570nm. Statistical values for PRI were calculated like R-Square (0.727), RMSE (0.267), P-value (2.787), standard error (2.979) and the statistical values for NRI were R-Square (4.223), RMSE (0.512), P-value (0.968), standard error(2.648).Linear regression was calculated for finding the relation between the data.

scholarly journals Melamine Faced Panels Defect Classification beyond the Visible Spectrum

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3644
Author(s):  
Cristhian Aguilera ◽  
Cristhian Aguilera ◽  
Angel Sappa
Keyword(s):  
Near Infrared ◽  
Visible Spectrum ◽  
Local Binary Patterns ◽  
Classification Performance ◽  
Support Vector ◽  
Feature Descriptor ◽  
Long Wavelength ◽  
Spectral Bands ◽  
Image Set ◽  
Long Wavelength Infrared

In this work, we explore the use of images from different spectral bands to classify defects in melamine faced panels, which could appear through the production process. Through experimental evaluation, we evaluate the use of images from the visible (VS), near-infrared (NIR), and long wavelength infrared (LWIR), to classify the defects using a feature descriptor learning approach together with a support vector machine classifier. Two descriptors were evaluated, Extended Local Binary Patterns (E-LBP) and SURF using a Bag of Words (BoW) representation. The evaluation was carried on with an image set obtained during this work, which contained five different defect categories that currently occurs in the industry. Results show that using images from beyond the visual spectrum helps to improve classification performance in contrast with a single visible spectrum solution.

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