Vivid Colors Research Articles

A Computer Vision‐Based Methodology to Estimate Fruit Colour Diversity in Ornamental Pepper (Capsicum spp.)

ABSTRACTFruit colour diversity within different ripening stages confers ornamental value for pepper plants. Using images can be helpful in analysing the fruit colour‐related genetic diversity and enable selecting accessions for ornamental purposes by avoiding subjectiveness. This study aimed to evaluate the phenotypic diversity among accessions of ornamental pepper using image processing techniques to identify fruit colours. Photos from 40 fruits from each of 12 accessions were captured by a camera from a smartphone. Separate channels and colour indices were extracted from the images to analyse the accessions using both dendrogram and principal components analysis. Dendrogram analysis allowed separating accessions with predominance of dark fruits from those whose fruits showed lighter and more vivid colours, with a cophenetic correlation coefficient of 0.811. The VARI and NGRDI vegetation indices were efficient in discriminating fruits with a predominance of green colour, and the BGI could be used to discriminate accessions with predominantly reddish‐brown fruits. The proposed method can be used in small‐scale breeding programs for accurately assessing the development of varieties regarding their fruit colour diversity.

Flexible Inverse Opal Structural Color Films with High Strength and Harsh Environment Stability.

Flexible photonic crystals (PCs) constructed by PCs and special polymers are very promising to achieve a combination of vivid structural colors, mechanical robustness, and environment stability. However, PCs that incorporate polymer binders are still susceptible to destruction and subsequent loss of structural color when subjected to significant external forces or harsh environments. Besides, because most of these polymers are highly flammable, crucial fire safety is difficult to be guaranteed in the application of these materials. In this study, we report a poly(m-phenyleneisophthalamide) inverse opal (PMIA IO) structural color film through a SiO2 PC template sacrificing method. Benefiting from the high rigid PMIA molecular structural configuration, the PMIA IO films are able to maintain their structural colors even in harsh conditions, such as large tensile stress, high and low temperatures, potent acids and bases, and ultraviolet radiation. More attractively, the PMIA IO films demonstrate excellent flame retardancy, with the limiting oxygen index (LOI) and flame retardant rating reaching 28 vol % and V0, respectively. We believe that the flexible structural color films with high strength, harsh environment stability, and flame retardancy, which are difficult for other structural color materials to possess simultaneously, have great potential for special applications in fire protection, national defense, aviation, marine, and aerospace fields.

Structural Color of Partially Deacetylated Chitin Nanowhisker Film Inspired by Jewel Beetle.

Nanochitin was developed to effectively utilize crab shells, a food waste product, and there is ongoing research into its applications. Short nanowhiskers were produced by sonicating partially deacetylated nanochitin in water, resulting in a significant decrease in viscosity due to reduced entanglement of the nanowhiskers. These nanowhiskers self-assembled into a multilayered film through an evaporation technique. The macro- and nanoscale structures within the film manipulate light, producing vibrant and durable structural colors. The dried cast film exhibited green and purple stripes extending from the center to the edge formed by interference effects from the multilayer structure and thickness variations. Preserving structural colors requires maintaining a low ionic strength in the dispersion, as a higher ionic strength reduces electrostatic repulsion between nanofibers, increasing viscosity and potentially leading to the fading of color. This material's sensitivity to environmental changes, combined with chitin's biocompatibility, makes it well-suited for food sensors, wherein it can visually indicate freshness or spoilage. Furthermore, chitin's stable and non-toxic properties offer a sustainable alternative to traditional dyes in cosmetics, delivering vivid and long-lasting color.

Silicon rich nitride: a platform for controllable structural colors

Abstract High refractive index dielectric materials like silicon rich nitride (SRN) are critical for constructing advanced dielectric metasurfaces but are limited by transparency and complementary metal oxide semiconductor (CMOS) process compatibility. SRN’s refractive index can be adjusted by varying the silicon to nitride ratio, although this increases absorption, particularly in the blue spectrum. Dielectric metasurfaces, which utilize the material’s high dielectric constant and nano-resonator geometry, experience loss amplification due to resonance, affecting light reflection, light transmission, and quality factor. This study explores the impact of varying the silicon ratio on structural color applications in metasurfaces, using metrics such as gamut coverage, saturation, and reflection amplitude. We found that a higher SRN ratio enhances these metrics, making it ideal for producing vivid structural colors. Our results show that SRN can produce a color spectrum covering up to 166 % of the sRGB space and a resolution of 38,000 dots per inch. Fabricated samples vividly displayed a parrot, a flower, and a rainbow, illustrating SRN’s potential for high-resolution applications. We also show that SRN can provide a better CIE diagram coverage than other popular metasurfaces materials. These findings highlight the advantages of SRN for photonic devices, suggesting pathways for further material and application development.

Photovoltaic Performance of Naphthol Blue Black Complexes and their Band Gap Energy

Along with the depletion of petroleum-based fuels, the development of renewable energy resources is a must. One of them is through DSSC (Dye Sensitized Solar Cells) technology, which has a dye sensitizer and semiconductor as the main components. The aim of this research is to investigating the photovoltaic performance of complexes series from metals (Mn(II); Fe(II); Co(II) and Ni(II)) and naphthol blue-black (NB) as a ligand. This investigation also successfully revealed factors that are highly influencing photovoltaic efficiency, namely the band-gap energy and the conductance of metal-NB complexes. The Fe(II)-NB complex has performed the highest photovoltaic activity as a result of the d-d electron transition and MLCT (Metal to Ligand Change Transfer) character which are covered by vivid color from the ligand. The bonding between metal and ligand was shown at a wavenumber of 316.33 cm-1 for M-N bonding and 486.06 cm-1 for M-O bonding. Fe(II)-NB complex had the narrowest band gap energy which is 5.86 eV and had the highest value of conductance and the highest efficiency, namely 0.0925%. This experiment successfully demonstrates that the narrower the energy gap of a molecule, the ability to transfer electrons is faster. Thus, the efficiency of the solar cell becomes higher. This investigation has proven that the narrow band gap makes the electron transfer becomes easier.

Size-Dependent Magnetic Responsiveness of a Photonic Crystal of Graphene Oxide Nanosheets.

A magnetically responsive photonic crystal of colloidal nanosheets can exhibit a controllable structural color, offering diverse potential applications. In this study, we systematically investigated how the lateral sizes of graphene oxide (GO) nanosheets affect their magnetic responsiveness in a photonic system. Contrary to the prediction that larger lateral sizes of nanosheets would be more responsive to an applied magnetic field based on the magnetic energy of anisotropic materials, we discovered that GO nanosheets with larger lateral sizes in the photonic system scarcely responded to a 12 T magnetic field. The lack of magnetic response may be due to the strongly restricted rotational motion of GO nanosheets by mutual electrostatic forces. In contrast, GO nanosheets with medium lateral sizes readily responded to the 12 T magnetic field, forming a uniaxially oriented structure that resulted in a vivid structural color. However, smaller GO nanosheets displayed a less vivid structural color, possibly because of less structural ordering of GO nanosheets. Finally, we found that the photonic crystal of GO nanosheets with optimized lateral sizes responded effectively to the 12 T magnetic field across various GO concentrations, resulting in a vivid and tunable structural color.

Cultural Perspectives on the Sustainable Use and Added Value of Plant-Based Food Dyes—A Case Study from Bulgaria

Raised personal health awareness and social environmental responsibility put pressure on the agri-food industry to adopt more sustainable ways of production, including the use of more natural ingredients, reducing waste, conservation and the regeneration of resources and energy. Plant-based colorants are ecologically friendly alternatives to artificial food dyes, especially with regards to the current reports on the adverse effects of some of the latter on human health. Various plants are traditionally used by many cultures to obtain vivid food coloration; however, the knowledge and means to produce them becomes less and less accessible to urbanized societies, and affordable organic alternatives are not always available on the market. An online questionnaire was performed to explore the awareness on plant-based dyes and pro-environmental attitudes of Bulgarian customers through the lens of Orthodox Easter eggs dyeing and the obtaining of plant dyes. From a total of 294 adult participants, only 5% reported a strict preference for natural dyes, while more than half of them (54%) were found to use natural and artificial ones concomitantly or switching between both. Of 45 plant taxa used for egg coloration, 12 were most frequently cited with many new additions of imported plants. Most of the used plant-based dyes were common fruits, spices, herbal infusions and even food waste like onion peels and avocado pits that were readily available from home gardens, markets and food shops. Additionally, we made a review of the scientific literature regarding their antioxidant and antimicrobial activity against food spoilage bacteria and foodborne pathogens isolated from eggs. All frequently used taxa were reported to exhibit antibacterial activities against Gram-positive and Gram-negative bacteria and possess antioxidant activity due to the presence of various polyphenols, essential oils and other compounds. Grape and red wine, roselle and stinging nettle are the species with the most diverse antibacterial activity, effective against 15 out of the 16 bacterial species of spoilage and foodbourn microorganisms included in our focus. The antimicrobial activities, however, were found mostly tested against bacterial strains in vitro, and further studies are needed to confirm their potential antibacterial activity when applied to Easter/boiled eggs or other food products. Our findings suggest that traditional cultural practices, as a multifaceted and engaging phenomenon, have the potential to promote environmental responsibility and a healthy lifestyle using both contemporary and traditional knowledge.

A new species of the pill millipede genus Rhopalomeris Verhoeff, 1906 (Diplopoda, Glomerida, Glomeridae) from Myanmar, and notes on Rhopalomeriscarnifex (Pocock, 1889).

The taxonomy of the pill millipede genus Rhopalomeris Verhoeff, 1906, which is restricted to Indochina and currently comprises six described species, is refined and updated. An integrative taxonomic approach was employed that combines morphological examination with DNA barcoding using the cytochrome c oxidase subunit I (COI) gene for species identification and delineation. The first objective was to confirm the identity of Rhopalomeriscarnifex (Pocock, 1889), a charismatic species known as the "candy pill millipede" due to its vivid coloration, based on specimens collected near the type locality in Myanmar. The second objective was to describe a new species, Rhopalomerisnigroflava Likhitrakarn, sp. nov., discovered in Linno Gu, Kayin State, Myanmar. This new species is distinguished by its small body size (5.1-9.7 mm long) and yellow body with contrasting brown to blackish markings on certain terga. In addition, the position of the telopod syncoxital lobe relative to the lateral syncoxite horns separates it from other Rhopalomeris species. The interspecific divergence between R.nigroflava Likhitrakarn, sp. nov. and other congeners ranges from 10.85% to 16.13%, based on uncorrected COI p-distances, while the intraspecific divergence was 0%-7.44%. A distribution map of and a revised identification key to all known species of Rhopalomeris are also provided.

Nutritional Benefits of Lycopene and Beta-Carotene: A Comprehensive Overview.

Certain carotene components, such as lycopene and beta-carotene, are found in tomatoes, carrots, sweet potatoes, etc. and are good for human health. It gives plants their distinctive red color. A class of lipid-soluble natural pigments known as carotenoids is the precursor of vitamin A and is vital for antioxidant defense against peroxides in cells and tissues. This review provides an overview of the current state of knowledge and research on the sources, structures, physiochemical properties, absorption and metabolism, functional advantages, and prevention of many diseases associated with lycopene and beta-carotene. These antioxidants have been linked to a lower risk of cardiovascular disease and cancer, and they also help draw pollinators to flowers. Carrots and sweet potatoes are also rich sources of beta-carotene, which strengthens the immune system and improves eye health. The vivid color of many plants reproductive organs, including flowers and fruits, is caused by carotenoid, a secondary metabolite that is produced in plastids. The distinctive red color and many other health advantages are attributed to lycopene. When ingested through food or supplements, lycopene and beta-carotene help manage and prevent a number of diseases, including cancer, metabolic, inflammatory, cardiovascular, hepatic, ophthalmic, skeletal, and infertility disorders. The main point is that toxicity is uncommon, and these carotenoids are generally accepted to be safe at different doses. Including these nutrients in your diet can improve your general health and provide illness prevention.

Engineering Fano resonances in plasmonic metasurfaces for colorimetric sensing and structural colors

In this paper, we present the design and fabrication of a plasmonic metasurface based on titanium dioxide (TiO2) nanowire arrays integrated with plasmonic layers. The structure is engineered to produce Fano resonances within the visible spectrum, resulting from the coupling of localized surface plasmon resonances, lattice modes, and nanowire's optical modes. Experimentally, we show that by tuning the geometrical features of the metasurface, such as the length, diameter, and period of the nanowires, a high-quality factor single peak can be achieved in the reflection spectra, resulting in vivid structural colors in bright field. To our knowledge, this is the first demonstration of such vivid colors with nanowire arrays in bright field reflections. When characterized by refractive index fluids around the refractive index of water, the plasmonic metasurface also showed great potential for biochemical colorimetric sensing. The best design demonstrated a bulk sensitivity of 183 nm/RIU with high Q resonance features and linear changes in color values using image processing.

Tunable MXene/WO3 Fabry−Pérot Microcavity Architecture for Bioinspired Soft Electrochromic Actuators with Vivid Colors

AbstractInspired by stimuli‐responsive creatures in nature, developing devices with synergistic color change and deformation will be of great value for realizing the adaptive variants. Yet, integrating adaptive color variation and deformation into a single device remains elusive. Herein, an intriguing electrochromic actuator based on MXene/WO3 bilayer film is developed with Fabry−Pérot (F–P) microcavity, which successfully integrates both functions of reversible deformation and vivid color variations into the same device. Upon applying a small electric field, the ion intercalation/de‐intercalation can synchronously alter the stress distribution and optical absorption of MXene/WO3, resulting in the dual response of electrochromic phenomenon and ultra‐fast deformation with a maximum angle of 95° within 10 s. Moreover, the F–P microcavity architecture with the physical light interaction additionally endows the bilayer film with a bright color gamut and high color tunability (yellow–green, purple, pink, blue, etc.). Furthermore, an asymmetric soft actuator based on MXene/WO3 bilayer film is assembled, which displays robust grasping ability and excellent cycling stability up to 1000 cycles. These findings may open new opportunities for somatosensory soft robots and next‐generation intelligent robots.

Effects of Dietary Microalgae Schizochytrium sp. Supplementation on Growth Performance and Skin Color in Jack Dempsey cichlid (Rocio octofasciata)

Growth retardation and decreased vivid coloration are significant issues in the ornamental fish market, particularly among cichlids. This study investigates the effects of Schizochytrium sp. microalgae supplementation on the growth and skin coloration of the Jack Dempsey cichlid (Rocio octofasciata). Three experimental groups were established: a control group (C) with no supplementation, and two microalgae-supplemented groups with 0.5% (S05) and 1% (S10). The control group was fed a commercial diet, while the S05 and S10 groups received the microalgae mixed with the commercial feed via spraying. A total of 135 Jack Dempsey fish (mean initial weight: 1.17 ± 0.14 g) were stocked into nine glass tanks (100 L each), with three replicates per group. After a 60-day feeding trial, growth indices revealed significant differences (p<0.05) between the control and algae-supplemented groups. The S10 group exhibited the highest final weight (FW) and the lowest feed conversion ratio (FCR). Additionally, the weight gain (WG) and specific growth rate (SGR) values for the S10 group were significantly higher than those of both the control and S05 groups (p<0.05). However, skin color parameters, including L* (brightness), a* (+red/-green axis), b* (+yellow/-blue axis), chroma (Ch), and hue angle (Hue), showed no statistical differences among the groups. This study demonstrates that a diet supplemented with 1% Schizochytrium sp. can enhance growth parameters and serve as a beneficial feed additive for Jack Dempsey cichlids.

PRN: progressive reasoning network and its image completion applications

Ancient murals embody profound historical, cultural, scientific, and artistic values, yet many are afflicted with challenges such as pigment shedding or missing parts. While deep learning-based completion techniques have yielded remarkable results in restoring natural images, their application to damaged murals has been unsatisfactory due to data shifts and limited modeling efficacy. This paper proposes a novel progressive reasoning network designed specifically for mural image completion, inspired by the mural painting process. The proposed network comprises three key modules: a luminance reasoning module, a sketch reasoning module, and a color fusion module. The first two modules are based on the double-codec framework, designed to infer missing areas’ luminance and sketch information. The final module then utilizes a paired-associate learning approach to reconstruct the color image. This network utilizes two parallel, complementary pathways to estimate the luminance and sketch maps of a damaged mural. Subsequently, these two maps are combined to synthesize a complete color image. Experimental results indicate that the proposed network excels in restoring clearer structures and more vivid colors, surpassing current state-of-the-art methods in both quantitative and qualitative assessments for repairing damaged images. Our code and results will be publicly accessible at https://github.com/albestobe/PRN.

Structural basis of selective beta-carotene binding by a soluble protein

β-carotene (BCR) is the most abundant carotenoid, a colorant, antioxidant, and provitamin A. The extreme hydrophobicity of this hydrocarbon requires special mechanisms for distribution in aqueous media, including water-soluble carotenoproteins. However, all known carotenoproteins prefer oxygenated carotenoids and bind BCR inefficiently. Here, we present the crystal structure of the BCR-binding protein (BBP) from gregarious male locusts, which is responsible for their vivid yellow body coloration, in complex with its natural ligand, BCR. BBP forms an antiparallel tubular homodimer with α/β-wrap folded monomers, each forming a hydrophobic 47Å long, coaxial tunnel that opens outward and is occupied by one s-cisC6-C7, all-trans BCR molecule. In the BCR absence, BBP accepts a range of xanthophylls, with reduced efficiency depending on the position and number of oxygen atoms, but rejects lycopene. The structure captures a pigment complex with a Takeout 1 protein and inspires potential applications of BBP as a BCR solubilizer.

Role of spatial correlation on the performance of colored photovoltaic modules with integrate disordered media

Colored photovoltaic (PV) modules with integrated disordered coatings exhibit attractive potential for generating renewable electricity. However, most existing studies on these modules rely on the assumption that the disordered coatings are random systems, neglecting the effects of spatial correlation. In this work, we thoroughly investigate the effects of spatial correlation on the color properties and performance of colored PV modules with integrated disordered coatings, using the full-wave electromagnetic simulation techniques. Our findings indicate that increasing the degree of spatial correlation results in a sharper and narrower reflectance peak, while having a negligible impact on the peak position. This trend suggests that the spatial correlation offers an alternative strategy for producing more vivid color, although it is less effective in expanding the color range. On the other hand, the spatial correlation has little impact on the power conversion efficiency (PCE) of PV modules. Therefore, it is feasible to produce colored PV modules with more vivid colors without significantly affecting the PCE by simply adjusting the degree of spatial correlation.

Target-inhibited MCOF-Apt-AuNPs self-assembly for multicolor colorimetric detection of Salmonella Typhimurium

Pathogens detection is a crucial measure in the prevention of foodborne diseases. This study developed a novel multicolor colorimetric assay to visually detect Salmonella Typhimurium (S. Typhimurium), by utilizing the etching process of gold nanorods (AuNRs) with TMB2+. The strategy involved the construction of nanozyme by assembling magnetic covalent organic framework (MCOF) with aptamer-conjugated AuNPs (Apt-AuNPs), exhibiting remarkable peroxidase-like activity to catalyze the oxidation of TMB/H2O2 and inducing the etching of AuNRs. The presence of S. Typhimurium could inhibit this process, resulting in the generation of vivid colors. The multicolor colorimetric assay could specifically determine S. Typhimurium from 102 to 108 CFU mL−1 in 60 min with visual detection limit of 102 CFU mL−1, and instrumental detection limit of 2.3 CFU mL−1. Moreover, detecting S. Typhimurium in chicken, milk, pork and lettuce samples has shown promise in practical applications.

Spectroscopic Investigation of Pearl Samples from Online Platforms and E-Marketplaces

P urchasing pearls from online platforms and e-marketplaces has been around for years, where buyers could join in the thrill of the show of opening pearls from oysters or mollusks. In exchange for those materials that claim to be pearls, buyers must pay a high price per piece. In this study, the spectroscopic properties of twenty-seven samples purchased from online platforms and e-marketplaces were revealed. The FTIR spectra show the characteristic peaks of aragonite at 1483, 716, 712, and 699 cm-1, while exhibiting the vaterite peaks at 882 and 879 cm-1. Correspondingly, Raman spectra indicate the ν1 symmetrical and ν4 in-plane bending modes of the carbonate at 1083, 701, and 704 cm-1. Thus, it clarified that all the samples are pearls. The SrO/MnO ratio acquired by energy dispersive X-ray spectroscopy (EDXRF) at an average of 0.44 suggested that the samples are freshwater pearls. Apart from the white pearl, the cause of the color of the sample is separated into two factors. The natural color, which is presented in cream and peach, is caused by polyene pigments. In contrast, vivid colors such as blue, violet, purple, and pink are shown as evidence of dyes. The UV-Vis reflectance spectra also present a different absorption between natural and dyed pearls.

Characteristics of Qinghai Traditional Painting Art-Literature Analysis

Qinghai’s traditional painting art, influenced by its diverse ethnic cultures and religious practices, is a unique fusion of Tibetan, Han, and Mongolian elements. Originating from ancient rock art, Qinghai painting has evolved into a complex system characterized by realism, symbolic representation, and vibrant colors. Tibetan Buddhism plays a significant role in shaping the themes and styles of Qinghai’s art, particularly in Thangka and mural paintings. These art forms, rich in religious symbolism, are not only visual representations of spiritual teachings but also educational tools that pass down cultural and moral values. Among Qinghai’s artistic traditions, Datong farmers' paintings stand out for their simplicity, vibrant colors, and strong connection to rural life, using expressive brushwork to depict local customs and daily activities. Meanwhile, Qinghai Thangka is notable for its symmetrical compositions, vivid colors, and intricate details, often portraying Buddhist deities in a harmonious and layered structure. Despite modernization challenges, Qinghai’s painting art continues to innovate while preserving its cultural heritage, with modern artists blending traditional techniques with contemporary elements to keep the tradition alive. This study explores the characteristics, cultural significance, and future of Qinghai traditional painting art, emphasizing its role in cultural identity and artistic development.

Sustainable preparation of nano monodispered ATP based color master batch and its application in PA6

AbstractAs a representative of dope‐dye, the color masterbatch method has been widely applied in modern dyeing processes, while it has difficulties in solving the dispersibility of inorganic pigments color master batch in the polymer matrix. In this work, attapulgite (ATP) was used as the adsorption carrier of inorganic pigments to prepare color‐dyed attapulgite (CD‐ATP). The selected environmentally friendly inorganic pigments were well adsorbed by ATP in KOH aqueous solution, and could stably be monodispersed in KOH aqueous solution for more than 168 h. Moreover, the KOH aqueous solution could be reused repeatedly, thereby, a sustainable method to prepare novel CD‐ATP was realized. By blending the as‐prepared CD‐ATP with polyamide‐6 (PA6), a series of dope‐dyed colorful PA6 composites was prepared. Scanning electron microscope (SEM) results indicated that the CD‐ATP was still monodispersed in the PA6 matrix, and endowed PA6 with a vivid color. Further studies show that the adding of CD‐ATP had little influence on the properties of PA6, but significantly reduced the water adsorption. This novel color‐dyed ATP has potential implications in making paper‐making blankets and is highly expected to have more extensive applications in many fields of life.

Infrared Stealth Coating with Tunable Structural Color Based on ZnO Spheres.

It is important to develop low infrared (IR) emissive coating with tunable structure color to improve the infrared-visible stealth performance of military equipment. In this work, uniform ZnO spheres are used as building units to construct photonic structures with both bright adjustable structure color and low IR emissivity due to the relatively high refractive index and low IR emissivity of ZnO. The vivid tunable structural colors are provided by the photonic bandgap of ZnO photonic crystals (PCs) or the quasi-bandgap of amorphous photonic crystals (APCs), respectively. Both ZnO PCs and APCs exhibited low IR emissivity in 3-5µm. The IR emissivity of 255nm ZnO PCis 0.483 and the IR emissivity of 255nm ZnO APC is 0.492 at 25°C. With the increase of temperature, the IR emissivity offurther decreased to 0.295 and 0.312 at 300°C. These structures can be applied to a variety of surfaces, and all these structures have good thermal and light stability as well. This work may open a simple and effective way to fabricate materials with good infrared-visible stealth performance, expanding the application of ZnO PCs and APCs coatings in the camouflage area.