Changes In Colors Research Articles

Self‐assembled small molecule spherulites under mild conditions: High solid‐state quantum yield and unique interconnected structural and fluorescent colors

AbstractSpherulites are generally fabricated from cooling polymer melts, while their fabrication under mild conditions or from small molecule materials has been barely reported. Besides, organic luminescent molecules typically suffer from low quantum yields in a solid state. Moreover, preparing material with interconnected and simultaneous changes in structural and fluorescent colors is challenging. Here, we present the first solution‐derived spherulites with unique interconnected structural and fluorescent colors, self‐assembled from stearoylated monosaccharides at room temperature. D‐galactose stearoyl ester self‐assembled into banded spherulites, containing twisted nanoplates and interconnected simultaneously changing structural and fluorescent colors. In comparison, D‐mannose stearoyl ester can only form non‐banded spherulites, which contain oriented nanoplates and uniform structural and fluorescent colors. Such materials revealed a novel negative correlation between fluorescence and birefringence, termed alignment‐promoted quenching propensity. Remarkably, the solid‐state fluorescence quantum yields of galactose and mannose‐derived spherulites are as high as 49 ± 2% and 51 ± 2% respectively, approximately ten times higher than those of unmodified monosaccharides. These quantum yield values are among the highest of reported organic nonconventional fluorophores and even comparable to those of conventional aromatic chromophores. Moreover, these spherulites manifested an unexpected excitation‐dependent multicolor photoluminescence with a broad‐spectrum emission (410−620 nm). They show multiple peaks in the photoluminescent emission spectra and broad fluorescence lifetime distributions, which should be attributed to the clustering of a variety of oxygen‐containing functional groups as emissive moieties.

Portable detection platform integrated with smartphone-assisted ratiometric fluorescence sensor for visual on-site detection of lead(Ⅱ) in aquatic products

Lead ion (Pb2+) pollution seriously threatens the quality of aquatic products. In this study, a ratiometric fluorescence sensor consisting of tangerine fluorescent Mn:ZnS QDs (T-QDs) and blue fluorescent Fe-MOF (B-MOF) was developed for selective recognition of Pb2+. Upon exposure to Pb2+, the fluorescence of T-QDs was quenched while the fluorescence of B-QDs was slightly changed, causing the changes of fluorescence colors from tangerine to blue with a detection limit (LOD) of 3.79 nmol/L. The sensor also had the strengths of low cost, easy to operate, excellent sensitivity and selectivity. Significantly, a portable detection platform integrated with the sensor was constructed to achieve on-site visual detection. As expected, the detection platform was successfully applied for testing Pb2+ with the LOD of 7.78 nmol/L. The strategy may not only provide a great capacity for on-site monitoring of Pb2+ in aquatic products but also expand application in environmental pollution detection.

Spectral studies of thermally stable Dy3+/Sm3+ co-doped Li2Ba5W3O15 phosphors for warm white LEDs

In the current study, a series of Li2Ba5W3O15: RE3+ (RE = Dy, Sm) [LBW:Dy3+/Sm3+] phosphors were prepared using a high-temperature solid-state method. X-ray diffraction, Scanning electron microscopy with energy-dispersive x-ray analysis scans showed that the crystal form was consistent with the standard LBW and comprised small irregularly shaped particles. Diffuse reflectance spectral (DRS) data was utilized to calculate the band gaps. Fluorescence study shows that LBW material doped with Dy3+ and Sm3+ yield distinct colors at 496 nm (blue) for Dy3+ and 582 nm (green-yellow), 612 nm (yellow), and 669 nm (red) for Sm3+ when excited by near-ultraviolet (336 nm) light. The observation of energy transfer between Dy3+ and Sm3+ ions play a role in modifying the luminescence of LBW:Dy3+/Sm3+ co-doped phosphors. With a constant excitation wavelength (λ Ex), different levels of activator doping lead to a change in the emission colors from their neutral white light to a deep orange-red region for LBW:Dy3+/Sm3+ phosphors. The decay curves demonstrate a decrease in lifetime with an increase in the concentration of activator ions (Sm3+). For D3S5 phosphor, the temperature-dependent photoluminescence characteristics were analyzed under λ Ex = 336 nm excitation. The results indicate excellent luminescence thermal stability with an activation energy of 0.16 eV at λ Ex = 336 nm. With its low color-correlated temperature and good thermal stability, the prepared phosphor sample shows potential as a solid-state emitting phosphor that can be used with UV chip stimulation for warm white LED applications.

Fluorescence chemosensor for anion recognition, solvatochromism and protein binding studies based on Schiff- base derivative

A new salicylidene-based chemosensor (E)-N1-(2-hydroxy-3-methoxy-5-nitrobenzylidene)-N2-phenylbenzene-1,2-diamine (MNP) has been developed by condensation of 3-methoxy-5-nitrosalicylaldehyde with N-phenyl-o-phenylenediamine and analysed using FT-IR, 1H-NMR and ESI-MS spectral techniques. The photophysical properties of MNP, including solvatochromism were investigated and the colour changed from bright yellow to red in the presence of water. This MNP specifically detects only Cu2+ with "turn-off" and a colour turned from light yellow to violet in CH3CN/H2O (9/1, v/v) mixture.The optimized geometry of the MNP-Cu complex was analyzed using DFT methods and the results is confirm the formation of the MNP-Cu complex. Besides, the F− and H2PO4−anions are preferentially sensed by the MNP in comparison to other anions, leading a "turn-off" and the colour change from light yellow to dark yellow in the THF medium. From the pH sensor data, the fluorescence intensity increased at pH 4.0 due to protonation of the -OH group. The interaction of the MNP with protein molecules (BSA, HSA) was investigated using absorption and emission spectral methods. The investigation computed values of the binding constant and the Stern-Volmer quenching constant demonstrated that the MNP had a far stronger affinity for BSA than for HSA. The interaction of the MNP with protein molecules was confirmed using docking studies.

The Influences of Contemporary Fashion to the Development of Men’s Baju Melayu in Malaysia

This study aims to analyse contemporary fashion influences that occurred in Malay men's Baju Melayu. Observations of modern contemporary Baju Melayu visual images from local designers were performed to identify the development of form, silhouette, colour, styling, and accessories. Analysis showed that the Malay men's Baju Melayu faces many changes in forms, silhouettes, colours, styles, and accessories in line with technological evolution, fashion openness, and the new lifestyle of the Malay men in Malaysia. The study hopes that local designers' new contemporary approaches can still portray Malay identity and sustain it over time.

Color preferences among selected adults in Ghana

This paper presents a study on color preferences among a sample of Ghanaian adults. Two surveys were conducted, with a total of 143 participants (50 in Survey 1, and 93 in Survey 2). The participants completed both printed and digital questionnaires to gather data on their color preferences. The results showed that blue was the most preferred color by both males and females in general, but not for specific items. In survey 2, a chi-square test on categorical variables revealed a significant relationship between gender and preference for light, dark, or bright colors (p=0.025), as well as gender and number of preferred colors per personal item (p=0.02). However, no significant relationships were found between gender and change of colors from childhood (p=0.73), gender and number of preferred colors (p=0.204), gender and most preferred colors (p=0.216), age, and the number of preferred colors (p=0.19). Interestingly, 66.3% of the participants in Survey 2 indicated that their preferred colors were based on innate attraction, regardless of whether their color preferences had changed or remained the same since childhood. Overall, blue and red were the most preferred colors, with a score of 34.4%. These findings provide valuable insights for design practitioners and communicators and offer a basis for future research on color preferences among Ghanaians.

Separation of benzene and toluene associated with vapochromic behaviors by hybrid[4]arene-based co-crystals

The combination of macrocyclic chemistry with co-crystal engineering has promoted the development of materials with vapochromic behaviors in supramolecular science. Herein, we develop a macrocycle co-crystal based on hybrid[4]arene and 1,2,4,5-tetracyanobenzene that is able to construct vapochromic materials. After the capture of benzene and toluene vapors, activated hybrid[4]arene-based co-crystal forms new structures, accompanied by color changes from brown to yellow. However, when hybrid[4]arene-based co-crystal captures cyclohexane and pyridine, neither structures nor colors change. Interestingly, hybrid[4]arene-based co-crystal can separate benzene from a benzene/cyclohexane equal-volume mixture and allow toluene to be removed from a toluene/ pyridine equal-volume mixture with purities reaching 100%. In addition, the process of adsorptive separation can be visually monitored. The selectivity of benzene from a benzene/cyclohexane equal-volume mixture and toluene from a toluene/ pyridine equal-volume mixture is attributed to the different changes in the charge-transfer interaction between hybrid[4]arene and 1,2,4,5-tetracyanobenzene when hybrid[4]arene-based co-crystal captures different vapors. Moreover, hybrid[4]arene-based co-crystal can be reused without losing selectivity and performance. This work constructs a vapochromic material for hydrocarbon separation.

Twisted Phosphors that Violate Kasha's Exciton Model in Organic Systems

Comprehensive SummaryKasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 states. This model holds true in most organic systems till now. Here we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular structures. When doped into different organic matrices, the twisted phosphor adopts different conformation, exhibits distinct phosphorescence colors and T1 energy levels, which violates Kasha's exciton model in organic system. Given that the change of phosphorescence colors and maxima can be readily distinguished by human eyes and conventional instrument, the twisted phosphors would be exploited as a new type of molecular probe, which would exhibit potential application in optical sensing and stimuli‐responsive systems.

EIoU-distance loss: an automated team-wise player detection and tracking with jersey colour recognition in soccer

The surge in demand for advanced operations in sports video analysis has underscored the crucial role of multiple object tracking. This study addresses the escalating need for efficient and accurate player and referee identification in sports video analysis. The challenge of identity switching among players, especially those with similar appearances, complicates multi-player tracking. Existing algorithms relying on manually labeled data face limitations, particularly with changes in jersey colors. This paper introduces an automated algorithm employing Intersection over Union (IoU) loss and Euclidean Distance (EUD), termed EIoU-Distance Loss, to track players and referees. The method prioritizes identity coherence, aiming to mitigate challenges associated with player and referee recognition. Comprising BackgroundSubtractionMOG2 for player and referee detection and IoU with EUD for connecting nodes across frames, the proposed approach enhances tracking performance, ensuring a clear distinction between different identities. This innovative method addresses critical issues in sports video analysis, offering a robust solution for tracking players and referees in dynamic game scenarios.

Construction of Highly Luminescent Lanthanide Coordination Polymers and Their Visualization for Luminescence Sensing.

NaH2SIP was selected as an organic ligand (NaH2SIP = 5-sulfoisophthalic acid monosodium salt). We successfully constructed a new class of lanthanide coordination polymers Ln-HS ([Ln(SIP)(DMF)(H2O)4]DMF·H2O; Ln = Eu, Tb, Sm, and Dy) by a simple solvothermal synthesis method. They exhibited excellent photoluminescence properties for Ln3+ ions, where Eu-HS and Tb-HS exhibited high quantum yields of 13.70 and 42.38%, respectively. The codoped lanthanide coordination polymers obtained by doping with different ratios of Eu3+/Tb3+ serve as excellent ratiometric thermometers with high sensitivities in the physiological temperature range, with values of 16.8, 7.0, and 14.5%·K-1, respectively. The luminescent colors of Tb0.95Eu0.05-HS and Tb0.94Eu0.06-HS exhibit variations from green to yellow to orange, achieving visualized luminescence in a narrow temperature range. The composite film material Tb0.94Eu0.06-HS@PMMA demonstrates this color variation. Next, Tb0.5Sm0.5-HS obtained by Tb3+/Sm3+ codoping was investigated. The difference in the luminescence colors visible to the naked eye at different excitation wavelengths and the change in luminescence colors occur in a very narrow temperature range. All of them show the great value of the visualized luminescence in practical anticounterfeiting, with double anticounterfeiting function and high security.

Development of a smartphone enabled, paper-based quantitative diagnostic assay using the HueDx color correction system.

Color correction is an important methodology where a digital image's colors undergo a transformation to more accurately represent their appearance using a predefined set of illumination conditions. Colorimetric measurements in diagnostics are sensitive to very small changes in colors and therefore require consistent, reproducible illumination conditions to produce accurate results, making color correction a necessity. This paper presents an image color correction pipeline developed by HueDx, Inc., using transfer algorithms that improve upon existing methodologies and demonstrates real-world applications of this pipeline in colorimetric clinical chemistry using a smartphone enabled, paper-based total protein diagnostic assay. Our pipeline is able to compensate for a variety of illumination conditions to provide consistent imaging for quantitative colorimetric measurements using white-balancing, multivariate gaussian distributions and histogram regression via dynamic, non-linear interpolating lookup tables. We empirically demonstrate that each point in the color correction pipeline provides a theoretical basis for achieving consistent and precise color correction. To show this, we measure color difference with deltaE (ΔE00), alongside quantifying performance of the HueDx color correction system, including the phone hardware, color sticker manufacturing quality and software correction capabilities. The results show that the HueDx color correction system is capable of restoring images to near-imperceptible levels of difference independent of their original illumination conditions including brightness and color temperature. Comparisons drawn from the paper-based total protein assay calibrated and quantified with and without using the HueDx color correction pipeline show that the coefficient of variation in precision testing is almost twice as high without color-correcting. Limits of blank, detection and quantitation were also higher without color-correction. Overall, we were able to demonstrate the HueDx platform improves reading and outcome of the total protein diagnostic assay and is useful for the development of smartphone-based quantitative colorimetric diagnostic assays for point-of-care testing.

Post-processing of galaxies due to major cluster mergers

The environments of galaxy clusters that underwent a recent (≤3 Gyr) major merger are harsher than those of dynamically relaxed clusters due to the global hydrodynamical disturbance and the merger-shock-heated intracluster medium. However, the impact of such extreme cluster interactions on the member galaxy properties is not very well constrained. We explore the integrated star formation properties of galaxies through galaxy colours as well as the morphology buildup in three nearby (0.04 < z < 0.07) young (∼0.6−1 Gyr) post-merger clusters – A3667, A3376, and A168 – and seven relaxed clusters to disentangle merger-induced post-processing signatures from the expected effects of high-density cluster environments. Exploiting optical spectroscopy and photometry from the OmegaWINGS survey, we find that post-merger clusters are evolved systems with uniform spiral fractions, a uniform fraction of blue galaxies, and constant scatter in the colour–magnitude relations, a regularity that is absent in dynamically relaxed clusters. While no clear merger-induced signatures were revealed in the global colours of galaxies, we conclude that different global star formation histories of dynamically relaxed clusters lead to considerable scatter in galaxy properties, resulting in the pre-merger cluster environment potentially contaminating any merger-induced signal of galaxy properties. We find red spirals to be common in both post-merger and relaxed clusters, while post-merger clusters appear to host a non-negligible population of blue early-type galaxies. We propose that while such merging cluster systems absorb extra cosmic web populations hitherto not part of the original merging subclusters, a ∼1 Gyr timescale is possibly too short see changes in the global colours and morphologies of galaxies.

Investigation of the Self-Cleaning Property of Photocatalytic Coatings at a Laboratory Scale

Self-cleaning products are commercially available to protect surfaces against soiling and avoid the high consumption of energy and chemical detergents necessary for cleaning. They are based on semiconductor oxides, mostly titanium dioxide (TiO2), which induce photocatalytic oxidation activity and superhydrophilicity. Therefore, we present an experimental procedure at a lab scale to assess the self-cleaning ability of various photocatalytic coatings (five TiO2-based commercial products and one lab-grade zinc oxide (ZnO) product) applied to mortar surfaces. The samples were artificially stained with three types of soiling: Congo red dye, diesel soot, and motor oil. They were exposed to the environmental cycle of UV illumination and water flow for two weeks and the changes in stain colors were first assessed with visual inspection. Then, spectrophotometry measurements were conducted before and after the self-cleaning experiment to calculate the color differences for each stain in the CIELab color space data. In addition, the coatings were characterized via X-ray diffraction analyses and water contact angle measurements. Results highlighted color changes for each stain and higher wettability (induced by OH radicals) of the coated surfaces, which favored surface washing and thus stain removal. Light also had a positive effect on the attenuation of the stains, particularly for the Congo red dye.

Resource-Saving Change of Special Colors

Resource-Saving Change of Special Colors

Losses of sexual dichromatism involve rapid changes in female plumage colors to match males in New World blackbirds.

Differences in coloration between the sexes (sexual dichromatism) can increase or decrease in a species through evolutionary changes in either or both sexes diverging or converging in their colors. Few previous studies, however, have examined the relative rates of such changes, particularly when dichromatism is lost. Using reflectance data from 37 species of the New World blackbird family (Icteridae), we compared evolutionary rates of plumage color change in males and females when dichromatism was either increasing (colors diverging) or decreasing (colors converging). Increases in dichromatism involved divergent changes in both sexes at approximately equal rates. Decreases in dichromatism, in contrast, involved changes in females to match male plumage colors that were significantly more rapid than any changes in males. Such dramatic changes in females show how selection can differ between the sexes. Moreover, these evolutionary patterns support the idea that losses of dimorphism involve genetic mechanisms that are already largely present in both sexes, whereas increases in dimorphism tend to involve the appearance of novel sex-specific traits, which evolve more slowly. Our results have broad implications for how sexual dimorphisms evolve.

Film Deposition of Electrochromic Metal Oxides through Spray Coating: A Descriptive Review

Electrochromism induces reversible changes of coloration in specific organic and inorganic materials through electrical charge/discharge reactions. When processed into thin films, electrochromic metal oxides can be integrated into glazing applications such as displays, rearview mirrors, goggles and, most notably, smart windows in energy-efficient buildings. Over the years, the use of spray coating as a liquid-based approach has been acknowledged for its cost-efficient, high-throughput samples production with a low volume consumption. It represents an interesting alternative to vacuum processes and to other wet methods, suitably responding to the current limitations of electrochromic thin films production by offering improved control over deposition parameters and capacities of up-scaling, together with lowered energetic and economic costs. The present review summarizes the main theoretical and practical aspects of spray coating, notably distinguishing room-temperature methodologies from pyrolysis-based, under heating protocols. The main families of functional electrochromic metal oxides are then screened and discussed, establishing how spray processing can challengingly lead to higher levels of optical contrast, commutation kinetics, coloration efficiency and cycling durability, and how low-toxic and environment-friendly precursors can be favored while sustaining large deposition areas.

The electrothermal color-changing fabric based on high-sensitivity thermochromic microcapsules

High sensitivity including low color hydrolysis and a narrow temperature range of color-changing is important to thermochromic microcapsules. However, it is a challenge for conventional ternary thermochromic systems to realize the fast change of colors. A new class of high-sensitivity microcapsules and electrothermal color-changing fabrics were designed and synthesized by introducing CNTs into thermochromic systems via microencapsulation and coating technology. The high sensitivity was attributed to the enhanced filler CNTs and binary core phase change materials (1-Tetradecanol/1-Octadecanol). Moreover, the dosage amount of CNTs, core-to-shell ratios, and particle size on the temperature sensitivity of microcapsules were investigated. From the results, the optimized microcapsules with regular spherical shape exhibited a narrow color-change temperature range of 30–35 ℃ and low color hydrolysis of 11 ℃. As the core wall ratio increased from 1:1–3:1, the color change temperature range of microcapsules became narrower and the color hydrolysis was lower. According to the phase change behaviors, thermochromic microcapsules with a melting enthalpy of 70.64 J/g performed a good thermal regulation capacity. Furthermore, the reversible thermochromic performance of obtained microcapsules remained stable through 500 thermal cycles, demonstrating excellent thermal cycling stability. Combining the obtained microcapsules and electrothermal fabrics, highly sensitive electro-thermochromic (ETC) fabrics by voltage were prepared. Under the supplied voltage of 6 V, the ETC fabrics exhibited outstanding cyclic electrothermal color-changing performance. This unique design concept for high-sensitivity ETC fabrics has great potential applications in personal thermal management, the cooling of electronic devices, visible displays, and so on.

Applicability and Freshness Control of pH-Sensitive Intelligent Label in Cool Chain Transportation of Vegetables.

Freshness is one of the main factors affecting consumers' purchase of food. The freshness indicator labels of packaged fresh green bell pepper (Capsicum annuum L.) and greengrocery (Brassica chinensis L.) were constructed, and pH-sensitive indicator labels based on the dye of anthocyanin and the mixing dye of methyl red and bromothymol blue were prepared in this study. At the same time, the color, chlorophyll content and vitamin C content of vegetables were measured in order to explore the applicability of indicator labels in the cool chain transportation of vegetables. Compared with the nature dye, the chemical dye-type indicator labels are more sensitive to pH changes. The results showed that the mixed indicator intelligent label had the best indication effect, and the MB 2 (mixing 1 g/L methyl red and bromothymol blue solutions at a ratio of 3:2 with a concentration of 70 mL/L in indicator film solution) indicator label could effectively indicate the freshness changes in vegetables during storage. Meanwhile, the color changes of the MB 2-type indicator label were correlated with the colors change of the sample, changes in nutrients, and changes in CO2 content inside the packaging. In addition, freshness detection models for green bell pepper and greengrocery by using color information of MB 2 intelligent labels were established. Hence, this pH-sensitive label can be applied as a promising intelligent packaging for non-destructively monitoring the freshness of respiratory and non-respiratory climacteric vegetables.

The effect of color vision resolution on intra-oral shade-selection accuracy.

Dentists must be able to identify subtle color changes as shade-matching is crucial in aesthetic dentistry. To determine whether color discrimination ability is related to shade-matching accuracy among dentists. The sensitivity of the normal-color vision population to different colors was investigated using Farnsworth Munsell 100 Hue (FM-100) test results. The FM-100 test was administered to 37 dentists at the Hospital of Stomatology, Jilin University. Sensitivity of dentists with normal-color vision to different colors was investigated using the FM-100 test. Participants were instructed to arrange color caps of various colors according to the gradual change in colors and the results were scored. Visual shade matching test using Vita 3D-MASTER shade guide was performed to determine shade-matching accuracy. The relationship between color discrimination ability and shade-matching accuracy was analyzed. The number of misplaced color caps in the FM-100 test was also calculated. The FM-100 test revealed that 16 and 21 participants had excellent and average color discrimination ability, respectively, and their shade-matching accuracies were 68.75% and 66.67%, respectively. No significant difference was observed in the shade-matching accuracy between the two groups. No significant correlation was observed between the color discrimination ability and shade-matching accuracy. In addition, the number of wrong color caps on the 43-63 color tray with the transition from blue-green to blue-purple was the highest according to Friedman's test. Color discrimination ability of dentists does not affect their visual shade-matching accuracy. Additionally, people with normal color vision are not sensitive to the transition from blue-green to blue-purple.

Statically Multiple Colors and Dynamically Infrared Emissivity Modulation Compatible Electrochromic Devices via Simple Fabry–Perot Photonic Structures

AbstractThe development of electrochromic devices (ECDs) that can dynamically modulate infrared (IR) emissivity while maintaining a wide color gamut distribution for visible (VIS)‐IR compatible spectral manipulation has been a long‐standing challenge. Current ECDs are limited by simultaneous changes in IR emissivity and VIS colors when subjected to external potential, restricting their potential applications. This work presents, for the first time, VIS–IR compatible ECDs capable of displaying VIS multicolor and dynamically modulating IR emissivity via a Ge/HfO2 Fabry–Perot cavity structure. The all‐solid‐state VIS‐IR compatible ECD with the structure of ITO/NiO/Ta2O5/Li/WO3/ITO/Ge/HfO2 achieves not only emissivity modulation of 0.20 at potentials of −2.5 V and +2.5 V in the wavelength range of 2.5–25 µm, but also, due to the presence of Fabry–Perot cavity, the novelty compatible device structure achieves static multicolor modulation, thus decoupling VIS and IR emissivity modulation. Additionally, a flexible VIS‐IR compatible ECD based on polyaniline is also constructed. This novel approach offers a promising possibility for multispectral compatible manipulation, VIS multicolor, and IR signal processing applications.