Spectral Color Research Articles

Tunable color and efficient energy transfer of KBaBP2O8:Ce3+, Tb3+ phosphors with low thermal quenching

Using functional phosphors that have a range of benefits, such as quick response to n-UV/blue light excitation, high quantum efficiency and low thermal quenching is crucial. In this work, we have utilized the traditional high-temperature solid-state reaction to synthesized Ce3+, Tb3+ single- and co-doped KBaBP2O8 (KBBPO) phosphors. The phase purity, crystal structure, surface morphology, decay behavior, thermal stability, the luminescence properties and energy transfer process from Ce3+ to Tb3+ were investigated in details. Due to the Ce3+ can adequately sensitize Tb3+, the co-doped phosphors can be effectively excited by near-ultraviolet (NUV) light. The emission color chromaticity for the various KBBPO phosphors varies from dark blue to bright green with the increased concentration of Tb3+. The energy transfer mechanism between Ce3+ and Tb3+ is dominated by the exchange interaction, while the efficiency of the energy transfer is calculated as 59.29%. The optimal KBaBP2O8: 0.02Ce3+, 0.05 Tb3+ phosphor demonstrated low thermal quenching, which only reduces 19.3% of the initial intensity at 150 °C. The new KBaBP2O8: Ce3+, Tb3+ phosphor will be a potential candidate for wide-color-gamut display backlights.

Fabrication of a GUMBOS-based ratiometric organo nanosensor for selective and sensitive detection of perchlorate ions that works in 100% water

This work intends to develop sensitive and easily applicable ionic liquids (ILs)-based fluorimetric sensors for detecting the explosive perchlorate (ClO4-) anions in the presence of other hazards and interferents. We have designed and developed an IL-compromising pyrene butyrate anion-based fluorophoric group of uniform materials based on organic salts (GUMBOS), PBIL, from sodium pyrene butyrate and trihexyltetradecylphosphonium chloride (P66614Cl) by simple ion exchange mechanism. Using reprecipitation methods, pyrene-based water-suspended nano-GUMBOS, nPBIL, has been fabricated and characterized by numerous analytical methods. The fabricated nano-GUMBOS display bright cyan color photoluminescence due to the excimer-like emission confirmed from the color chromaticity diagram. Interestingly, due to the addition of ClO4- ions, there is a blue shift in the UV–visible absorption spectrum of the nPBIL solution with a simultaneous decrease in Mie-scattering. Consequently, there is a continuous decrease in the excimer-like emission of nPBIL with the synchronized increase in monomeric emission. We can conclude from both UV–visible absorption and emission spectra that the ClO4- ion displaces the anionic pyrene butyrate moiety of our nPBIL due to its high polarizability. The limit of detection (LOD) of the as-fabricated sensor is estimated to be 7.17 nM which is very much lower than the US Environmental Protection Agency (USEPA) predicted permeable level of perchlorate in drinking water (15 μgL−1). An efficient test kit has been fabricated and demonstrated for on-site detection of ClO4- ions in remote areas. This ion exchange-mediated substance release from such nano-GUMBOS systems is a distinctive and innovative way to design and develop efficient sensors for precisely detecting and quantifying ClO4- ions.

Stratigraphic architecture and distribution patterns of submarine fan-reservoir elements: insights derived from the Pliocene and Pleistocene Bengal Fan

ABSTRACT 3-D seismic data from the Bengal Fan along with spectral decomposition and RGB color blending techniques display stratigraphic architectures and spatiotemporal distribution patterns of submarine fan-reservoir elements in stark detail. Seven reservoir elements are recognized in Pliocene and Pleistocene channel–lobe complexes (i.e., subfans) developed on the northeastern fringe of the Bengal Fan. Among them, crevasse, overbank, and avulsion splays are not well acknowledged by standard models of submarine fan-reservoir elements. Crevasse splays decrease in thicknesses towards ancestral channels, and are capped by overlying levees, whereas overbank and avulsion splays increase in thicknesses towards ancestral channels and cap underlying levees. Crevasse and avulsion splays exhibit lobate planform morphology and are linked updip to ancestral channels by feeder channels, whereas overbank splays display tongue-like planform morphology and lack feeder channels. Fills of laterally migrated channel-complex sets (CCSs) appear only in early stage of subfan evolution, whereas fills of vertically stacked CCSs can appear either in middle or late stages of subfan evolution. The inner segment of the documented subfans fostered infills of both laterally migrated and vertically stacked CCSs, whereas the outer segment of the studied subfans contains terminal lobe complexes and distributary-channel fills. Crevasse, overbank, and avulsion splays can appear either in middle or late stages of subfan evolution, and mainly occur in overbank environments of middle segments of the documented subfans, which are dominated by muddy facies as predicted by the standard model of submarine fan-reservoir elements. Pliocene and Pleistocene subfans demonstrate the importance of splay processes in submarine-fan evolution, and this has implications for understanding the evolution of the volumetrically largest sediment accumulations on Earth and the distribution of submarine fan-reservoir components. The downlap of subsequent levees onto crevasse splays and overbank splays created stratigraphic traps with the potential for large hydrocarbon accumulations.

Enhancement of stimulated emission in Eu3+ activated oxyfluoroborotellurite glasses for reddish orange laser material

Eu3+ activated oxyfluoroborotellurite glasses are enhancement stimulated emission by substitution of B2O3 with NaF whereas concentration of Eu3+ are fixed at 1.00 mol%. The present glasses have been prepared by melt quenching method. Seven absorption bands of present glasses have been observed in UV–VIS and NIR regions which originated from ground 7F0 and thermally populated 7F1 states to excited states. The absorption transitions of 7F0→5L6 and 7F0→7F6 were more intense compared to all transitions. The substitution of B2O3 with NaF has led to minor change absorption intensities. By stimulating with 395 nm, the emission spectra of present glasses exhibited four peaks which corresponding to 5D0→7F1,2,3,4 transitions. The transition of 5D0→7F2 showed the highest emission intensity. The substitution of B2O3 with NaF can enhance emission intensity due to the reduction of hydroxyl group. While the highest emission intensity has been found to be 35 mol% of NaF concentration. The absorption and emission results have been calculated stimulated emission by using Judd-Ofelt (JO) theory. The stimulated emission is found to be 109.1 × 10–21 cm2. Including the branching ratio is higher than 0.50. In the frame of chromaticity color coordinate which the present glasses are fallen in the reddish orange region. The results indicate that Eu3+ activated oxyfluoroborotellurite glasses could be used potentially for reddish orange laser material.

Structural, optical, and luminescence properties of Dy3+ -activated potassium calcium silicate phosphor for white light-emitting diodes.

A dysprosium (Dy3+ )-activated potassium calcium silicate (K4 CaSi3 O9 ) phosphor was prepared using a solid-state synthesis route. The phosphor had a cubic structure with the space group Pa as confirmed using X-ray diffraction (XRD) measurements. Details of surface morphology and elemental composition of the as-synthesized undoped KCS phosphor was obtained using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The chemical structure as well as the vibrational modes present in the as-prepared KCS phosphor was analyzed using Fourier transform infrared (FT-IR)spectroscopy. Diffuse reflectance spectra (DRS) were used to determine the optical bandgap of the phosphors and were found to be in the optical range 3.52-3.71 eV. Photoluminescence (PL) spectra showed intense yellow emission corresponding to the 4 F9/2 →6 H13/2 transition under 350 nm excitation. Commission International de l'Eclairage colour chromaticity coordinates were evaluated using the PL spectral data lie within the white region. Dexter theory and the Inokuti-Hirayama (I-H) model were applied to study the nature of the energy transfer mechanism in the as-prepared phosphors. The relatively high activation energy of the phosphors was evaluated using temperature-dependent PL (TDPL) data and confirmed the high thermal stability of the titled phosphor. The abovementioned results indicated that the as-prepared KCS:Dy3+ phosphor was a promising candidate for n-UV-based white light-emitting diodes.

A Fiber-Optic Array Spectrometer With Parallel Multichannel Optical Lock-in Detection and its Application to in Situ Lighting Measurements

This paper describes a new optical spectroscopy instrument achieving lock-in detection in all its spectral output channels in a parallel and simultaneous fashion. It is based on two identical compact array spectrometers working in phase quadrature thanks to optical modulators synchronized with an external reference signal. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">In the application example, the optical lock-in spectrometer was used to perform spectral irradiance measurements with commercial LED lamps exhibiting temporal light modulation at different frequencies. A remote sensing optical device was designed to measure from a distance the temporal luminous waveform of a specific LED lamp and send it to the reference input of the optical lock-in spectrometer. When the lamps were operating together on top of a large continuous luminous background, the optical lock-in spectrometer successfully retrieved the respective spectral irradiance distributions and color parameters of each lamp, allowing their characterization to be performed independently of the other light sources illuminating the sensor during the measurements.

Decreased perifoveal ganglion cell complex thickness - a first sign for macular damage in patients using hydroxychloroquine.

Aim: To examine ganglion cell complex (GCC) thickness detected by optical coherence tomography (OCT) in patients using hydroxychloroquine (HCQ), without any structural and functional macular changes to evaluate the initial symptoms of macular toxicity for early diagnosis before clinical evaluation. Methods: Eighty eyes of forty patients (Group 1) and forty eyes of twenty healthy volunteer persons (Group 2) were included in the study. Detailed ophthalmologic and mydriatic fundus examination were applied to all patients and volunteers (controls). Spectral domain OCT, visual field (VF) and color vision test were performed. Measurements of macula thickness, GCC thickness (involving nerve fiber layer, ganglion cell layer and inner plexiform layer) and peripapillary retinal nerve fiber layer (RNFL) were performed with OCT. Patients with retinal pigment epithelial changes, VF paracentral scotoma and defected color vision were excluded from the planned study. Results: Perifoveal GCC layer thickness in all quadrants was significantly thinner in group 1 compared to group 2 (p=0.017, p=0.001, p=0.019, p=0.001). The mean global inferior hemifield and nasal quadrant RNFL thickness were lower than in the control groups (p=0,012, p=0,009, p=0,005, respectively). Conclusion: Changes in the thickness of nerve fiber layer and ganglion cell layer detected by optical coherence tomography can be thought to be used as a diagnostic aid for the early diagnosis of hydroxychloroquine-toxic maculopathy Abbreviations: GCC = Ganglion cell complex, OCT = Optical coherence tomography, HCQ = Hydroxychloroquine, BCVA = Best-corrected visual acuity, IOP = Intraocular pressure, VF = Visual field, RNFL = Retinal nerve fiber layer, SD OCT = Spectral-domain optical coherence tomography, mfERG = Multifocal electroretinogram, FAF = Fundus autofluorescence, IS/ OS = Inner segment-outer segment junction, SITA = Swedish Interactive Threshold Algorithm, RA = Rheumatoid arthritis, SLE = Systemic lupus erythematosus, SS = Sjogren syndrome.

Warm to neutral white light emissions from Dy3+–Eu3+ co-doped glass ceramics containing NaBSiO4 crystalline phase for W-LEDs applications

This paper reports on the structural, optical and luminescence studies of Dy3+–Eu3+ co-doped glass ceramics that are obtained via thermal treatment method. The initial confirmation on glass ceramics with the formation of NaBSiO4 crystalline phase was made through XRD study. The FTIR study showed the vibrations of network formers (B2O3, SiO2) and other functional groups. The quantity of non-bridging oxygens (NBOs) are increased in the glass ceramics with increase in annealing temperature. The absorption spectra (UV–visible-NIR) showed the possible transitions of Dy3+ and Eu3+ ions in the glass ceramics. A red-shift in the absorption band-edge and reduction in the optical band gap values were obtained for glass ceramics owing to their heating temperatures. Photoluminescence studies showed the excitations of Dy3+ and Eu3+ ions under 575 nm and 613 nm emission wavelengths. The obtained NaBSiO4 crystalline phase in the glass ceramics has enhanced the luminescence intensity, and lifetimes of Dy3+ and Eu3+ ions compared to unheated precursor glass when excited under 350 nm and 393 nm. Color chromaticity diagram and correlated color temperature (CCT) values showed a shift in the color of light from warm white of precursor glass to neutral white of glass ceramics. The overall results justify the possibility of considering the Dy3+-Eu3+ co-doped glass ceramics as efficient materials for solid-state lighting applications like W-LEDs.

An azine-based chromogenic, fluorogenic probe for specific cascade detection of Al3+ and PO43- ions

An azine-based chromo-fluorogenic sensor, 2,2′-((1E,1′E)-hydrazine-1,2-diylidenebis(methanylyidene)) bis(4-nitrophenol) (DBMN), has been introduced for cascade detection of Al3+ and PO43- ions with high selectivity and sensitivity with a detection limit in the nM to μM range. Upon introducing Al3+ ions into the DBMN solution, a remarkable colorimetric change from yellow to colorless has been noticed in the naked eye due to inhibiting the intramolecular charge transfer process. A 120 times photoluminescence intensity enhancement displaying bluish-green fluorescence under the exposure of a 365 nm UV lamp is observed because of chelation-enhanced fluorescence (CHEF) from the solution of Al3+ ions chelated DBMN complex, which is also well-supported by the color chromaticity diagram. Al3+ ions chelated DBMN complex is selective and sensitive to detecting PO43- ions by rebirthing DBMN. A paper strips-based test kit has been fabricated for on-site cascade detection of Al3+ and PO43- ions, respectively. By employing either Al3+ and PO43- ions as single chemically encoded input and photoluminescence intensity as optical output, we have framed YES and NOT single input and single output opto-chemical logic circuits. Also, based on the photoluminescence off–on-off mechanism, we have designed two inputs and one output-based INHIBIT logic gate with the help of sequential addition of Al3+ and PO43- ions as the two chemically encoded inputs and the luminosity at 500 nm as a single output. Also, a set-reset memorized molecular device has been framed based on photoluminescence as the optical output due to the sequential addition of Al3+ and PO43- ions in the DBMN solution.

Efficient tunable photoluminescence of Dy3+/Eu3+ co-doped OFSZBS glasses for warm white LEDs

A series of oxyfluoride strontium zinc borosilicate (OFSZBS) glasses co-doped with Dy3+/Eu3+ ions was prepared via melt quench method. The structural properties were examined using XRD and scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDX) on DE2.0 and undoped OFSZBS glasses, respectively. UV–Vis absorption spectroscopy was used to evaluate the direct & indirect energy band gaps. At different excitations (348, 362, 385 and 393 nm), the photoluminescence (PL) spectra were observed with tuned light. Warm white light was generated through the Dy3+ (4F9/2→6H15/2, 6H13/2) and Eu3+ (5D0→7F2) transitions. Dexter Reisfield approximation applied to PL data revealed a dipole-dipole (d-d) mechanism accountable for the energy transfer (non-radiative) between sensitizer (Dy3+) and activator (Eu3+) ions. The energy transfer efficiency in the co-doped glass samples was found between 8% to 50%, depending on the doping. The Inokuti-Hirayama (I-H) fitting of PL decay profiles also confirm the energy transfer mechanism. The CIE chromaticity color coordinates observed for OFSZBSDE2.0 glass also confirm the color tunability. The above findings reveal the applications of as-prepared Dy3+/Eu3+ co-doped OFSZBS glasses excited using n-UV light for warm white LEDs and tuned devices.

Synthesis of multicolor silver nanostructures for colorimetric sensing of metal ions (Cr3+, Hg2+ and K+) in industrial water and urine samples with different spectral characteristics

In this work, we have synthesized four different color (yellow, orange, green, and blue (multicolor)) silver nanostructures (AgNSs) by chemical reduction method where silver nitrate, sodium borohydride and hydrogen peroxide were used as reagents. The as-synthesized multicolor AgNSs were successfully functionalized with bovine serum albumin (BSA) and applied as a colorimetric sensor for the assaying of metal cations (Cr3+, Hg2+, and K+). The addition of metal ions (Cr3+, Hg2+, and K+) into BSA functionalized AgNSs (BSA-AgNSs) causes the aggregation of BSA-AgNSs, and are accompanied by visual color changes with red or blue shift in the surface plasmon resonance (SPR) band of BSA-AgNSs. The BSA-AgNSs show different SPR characteristic for each metal ions (Cr3+, Hg2+, and K+) with exhibiting different spectral shift and color change. The yellow color BSA-AgNSs (Y-BSA-AgNSs) act as a probe for sensing Cr3+, orange color BSA-AgNSs (O-BSA-AgNSs) act as probe for Hg2+ ion assay, green color BSA-AgNSs (G-BSA-AgNSs) act as a probe for the assaying of both K+ and Hg2+, and blue color BSA-AgNSs (B-BSA-AgNSs) act as a sensor for colorimetric detection of K+ ion. The detection limits were found to be 0.26 μM for Cr3+ (Y-BSA-AgNSs), 0.14 μM for Hg2+ (O-BSA-AgNSs), 0.05 μM for K+ (G-BSA-AgNSs), 0.17 μM for Hg2+ (G-BSA-AgNSs), and 0.08 μM for K+ (B-BSA-AgNSs), respectively. Furthermore, multicolor BSA-AgNSs were also applied for assaying of Cr3+, and Hg2+ in industrial water samples and K+ in urine sample.

Which visual elements on packaging affect perceived credibility? A case study of in vitro diagnostic kits

With increasing public health awareness and the unprecedented global health crisis, consumers' demand for in vitro diagnostic (IVD) reagents is gradually increasing. However, consumer mistrust remains a significant barrier to purchasing and using IVD products. Pharmaceutical companies and governments prioritizing direct-to-consumer (DTC) marketing have recognized the impact of visual packaging elements on consumer perception. Thus, we researched whether visual packaging elements systematically influence consumers' perceived credibility of IVD products' credence attributes, namely, their ability to protect personal and public health. Combining previous related studies, this study was conducted experimentally with rapid diagnostic test (RDT) kits, assuming that the visual elements (i.e., typeface, color, pattern, and information) of packaging can influence consumers' perceived credibility of RDT kits and explored which elements are more credible. Questionnaires were randomly selected and assigned to 216 participants. The results indicated that all four elements influenced the participants’ perceived credibility. Specifically, a sans serif typeface, realistic pattern, chromatic color, and more information made the participants feel more credible. Our research results fill a gap in the consumer perception of over-the-counter (OTC) pharmaceutical products by providing new insights into dissecting consumer perceptions. This offers a novel design strategy for online and offline marketing and promotional efforts by different companies and governmental organizations.

Color Semantics of the Cultural Landscape

A cultural landscape is the result of a continuous interaction between the surrounding natural landscape and culture. Meanings, symbols, and codes of culture are an integral part of it. This paper is a review of publications on current research over the past 20 years. The aim is to analyze the existing research practices, which are based on factual evidence and existing theoretical foundations, using an interdisciplinary approach, in order to come closer to a sufficiently holistic understanding of the coloristic semantics of the cultural landscape. Such a review and analysis of disparate studies allows for the first time the correlation of different types of cultural landscapes (urban, rural, gardens, and parks) and different types of signifier functions performed in them by color—signals, indices, iconic models, conventional signs or symbols, zero, or empty signs. The author analyzes the difference in the semantics of chromatic and achromatic colors and explores the landscape chromodynamics, namely, by creating the first-ever classification of the types and meanings of color foci of various durations—from days to decades. Color loci signs are continuously communicating in the cultural landscape, which is a field of constant “cultural explosion”, where traditional cultural meanings are transmitted and new meanings are generated. The author comes to the conclusion that color symbolism is part of the “landscape-as-text” containing certain information—“messages” of culture to itself. In these messages, color has sacral, temporal, and historical semantics, thus creating an extended semantic frame for the reproduction of cultural codes.

Europium-Doped Calcium Silicate Nanoparticles as High-Quantum-Yield Red-Emitting Phosphors.

Europium ion-activated calcium silicate phosphors (Ca2SiO4:Eu3+) with sharp red-light emission were fabricated via the hydrothermal method. The size of Ca2SiO4:Eu3+ phosphors was controlled between 20 and 200 nm by precursor silicate particle sizes. Systematic studies to determine morphology, crystal phase, and photoluminescence (PL) were carried out for all the phosphors, and their optical efficiencies were compared. We found that the luminescence intensity and emission wavelength of Ca2SiO4:Eu3+ phosphors depend on their particle sizes. Particularly, the Ca2SiO4:Eu3+ synthesized with 20 nm silica seed contains the most intense red emission, high color purity, and high PL quantum yield. For the 20 nm-sized Ca2SiO4:Eu3+ phosphor, PL quantum yields are measured to be above 87.95% and high color purity of 99.8%. The unusually high intensity of 5D0 → 7F4 emission (712 nm) is explained by structural distortion arising from silicate particle size reductions. We show that the obtained phosphor is a suitable candidate for solid-state lighting as a red component through CIE chromaticity coordinate and color purity measurements. Furthermore, the Ca2SiO4:Eu3+ particles are examined for their validity as promising bio-imaging probes through cell labeling and imaging experiments and biodegradability studies.

Robust near-infrared-based plastic classification with relative spectral similarity pattern

Sensor-based material flow characterization techniques, particularly hyperspectral imaging in the near-infrared (NIR) range, can recognize materials quickly, accurately, and economically. When identifying materials using NIR hyperspectral imaging, extracting influential features from high-dimensional wavelength information is essential for effective recognition. However, spectral noise from the rough and contaminated surfaces of objects (especially un-shredded waste) degrades the feature-extraction performance, which in turn deteriorates the material classification performance. In this study, we propose a real-time feature-extraction method, named relative spectral similarity pattern color mapping (RSSPCM), to robustly classify materials in noisy environments, such as plastic waste sorting facilities. RSSPCM compares relative intra- and inter-class spectral similarity patterns, instead of individual similarity, to class-representative spectra alone. Recognition targets have similar chemical makeups that are applied to feature extraction as an intra-class similarity ratio. The proposed model is robust owing to the remaining relative similarity trends found in a contaminated spectrum. We evaluated the effectiveness of the proposed method using noisy samples obtained from a waste-management facility. The results were compared with two spectral groups obtained at different noise levels. Both results showed high accuracy as there was an increased number of true positives for low-reflectance regions. The average F1-score values were 0.99 and 0.96 for low- and high-noise sets, respectively. Furthermore, the proposed method showed minimal F1-score variations between classes (standard deviation of 0.026 for the high-noise set).

Colour–Touch Cross-Modal Correspondence and Its Impact on Single-Modal Judgement in Multimodal Perception

Abstract This study explored the colour–touch cross-modal correspondence and its impact on colour–touch multisensory perception. Two laboratory experiments were conducted based on a pre-experiment. In the first experiment, participants chose the colour according to their tactile sense against the vibration generated by the smartphone simulator. A positive cross-modal correspondence was obtained between the vibration amplitude and the colour chroma, indicating the existence of a colour–touch correspondence. The correspondence between vibration parameters and colour hue was preliminarily explored. The impact of the correspondence on the multisensory senses was investigated in the second experiment. Different stimulus combinations were played on a smartphone. The participants were asked to choose the perceived stimulus level. The data illustrated that a better correspondence improved judgement accuracy and reduced reactiontime. Overall, this study offers evidence for colour–touch cross-modal correspondence and presents its potential influence on the single-modal judgement in multimodal perception. The results can be applied in further cross-modal studies, assisting barrier-free society construction and multimodal interface design.

Color and Texture Analysis of Textiles Using Image Acquisition and Spectral Analysis in Calibrated Sphere Imaging System-II

The extended application of device-dependent systems’ vision is growing exponentially, but these systems face challenges in precisely imitating the human perception models established by the device-independent systems of the Commission internationale de l’éclairage (CIE). We previously discussed the theoretical treatment and experimental validation of developing a calibrated integrated sphere imaging system to imitate the visible spectroscopy environment. The RGB polynomial function was derived to obtain a meaningful interpretation of color features. In this study, we dyed three different types of textured materials in the same bath with a yellow reactive dye at incremental concentrations to see how their color difference profiles tested. Three typical cotton textures were dyed with three ultra-RGB remozol reactive dyes and their combinations. The color concentration ranges of 1%, 2%, 3%, and 4% were chosen for each dye, followed by their binary and ternary mixtures. The aim was to verify the fundamental spectral feature mapping in various imaging color spaces and spectral domains. The findings are quite interesting and help us to understand the ground truth behind working in two domains. In addition, the trends of color mixing, CIE color difference, CIExy (chromaticity) color gamut, and RGB gamut and their distinguishing features were verified. Human perception accuracy was also compared in both domains to clarify the influence of texture. These fundamental experiments and observations on human perception and calibrated imaging color space could clarify the expected precision in both domains.

Site preference-based luminescence studies in Eu doped calcium magnesium silicate phosphor: A combined experimental and DFT approach

The luminescence of Eu3+ doped calcium magnesium silicate (CMS: Eu3+) phosphor is studied experimentally by optimizing the single diopside structure in the solid state reaction method and theoretically verified using the first principle density functional theory (DFT) calculation. Field Emission Scanning Electron Microscopy (FESEM) analysis shows a transition from agglomerated morphology to particle formation at 900 °C. A combination of diopside and akermanite structures are formed at 800 °C, whereas a single diopside phase is optimized from 900 °C onwards. DFT calculation has been carried out to identify the lattice parameters of the diopside structure of calcium magnesium silicate (CMS) and Eu3+ doped CMS by replacing Eu3+ in the lattice site of Ca and Mg to identify the stable structure. The lattice expansion is minimal when Eu3+ replaces the Ca2+ position. Lattice parameters of the diopside phase calculated using Rietveld refinement of the XRD pattern are in agreement with DFT findings. FTIR analysis confirms a redshift corresponding to Ca–O and a blueshift corresponding to Mg–O stretching wavenumbers due to the structural modification of CMS due to Eu addition in the lattice. The stability and site preference of Eu3+ ion in CMS is determined from the mixing energy (ΔHm) of Eu doped in the Ca site and Mg site of CMS separately via DFT calculation and confirm that the mixing energy is minimum when Eu3+ replaces Ca lattice position. UV–visible, DRS spectroscopy confirms a bandgap of ∼6 eV for CMS and CMS: Eu3+. Luminescence studies confirm constant peak splitting in the 5D0→7FJ (J = 1,2,4) transitions due to the crystal field effect caused due to the incorporation of Eu3+ in the diopside structure with dodecahedral coordination. Eight coordinated site preference of Eu3+ in diopside is confirmed via DFT calculations. Modification in asymmetry ratio (R-ratio) with temperature also corroborates with modification in the intensity of photoluminescence spectra dictated by the reduction in inversion symmetry. CIE color chromaticity analysis shows a coordinate of (0.61, 0.39) in the red region of visible spectra with a color purity of 83.49% irrespective of annealing temperature.

An improved golden jackal optimization for multilevel thresholding image segmentation.

Aerial photography is a long-range, non-contact method of target detection technology that enables qualitative or quantitative analysis of the target. However, aerial photography images generally have certain chromatic aberration and color distortion. Therefore, effective segmentation of aerial images can further enhance the feature information and reduce the computational difficulty for subsequent image processing. In this paper, we propose an improved version of Golden Jackal Optimization, which is dubbed Helper Mechanism Based Golden Jackal Optimization (HGJO), to apply multilevel threshold segmentation to aerial images. The proposed method uses opposition-based learning to boost population diversity. And a new approach to calculate the prey escape energy is proposed to improve the convergence speed of the algorithm. In addition, the Cauchy distribution is introduced to adjust the original update scheme to enhance the exploration capability of the algorithm. Finally, a novel "helper mechanism" is designed to improve the performance for escape the local optima. To demonstrate the effectiveness of the proposed algorithm, we use the CEC2022 benchmark function test suite to perform comparison experiments. the HGJO is compared with the original GJO and five classical meta-heuristics. The experimental results show that HGJO is able to achieve competitive results in the benchmark test set. Finally, all of the algorithms are applied to the experiments of variable threshold segmentation of aerial images, and the results show that the aerial photography images segmented by HGJO beat the others. Noteworthy, the source code of HGJO is publicly available at https://github.com/Vang-z/HGJO.

Teknor Apex creates color masterbatches for UBQ Materials’ bio-based thermoplastic

On May 4, 2023, UBQ Materials announced that Rhode Island based global compounder, Teknor Apex announced a new color masterbatch solution for UBQ Materials’ bio-based thermoplastic, UBQ™. Expanding its partnership with the climate-tech developer, Teknor Apex's new solution includes the development and supply of highly chromatic colors that incorporate UBQ's sustainable products made entirely from unsorted organic and unrecyclable waste.