Vivid Colors Research Articles

Olga Albizu’s Lyrical Abstraction and the Borders of the Canvas

The abstractionist paintings of Puerto Rican artist Olga Albizu (1924–2005) gained prominence in the late 1950s when her work debuted in galleries across the Americas and entered the commercial music industry with RCA and Verve records. However, existing scholarship has failed to capture the complex relationship between Albizu’s anti-commercial abstractionist aesthetic and its mass reproduction as cover art for vinyl records during the Cold War era. Returning to the canvas to explore the iconographic, formal, and aesthetic qualities of Albizu’s work within its sociohistorical post-World War II context, this study reveals Albizu’s devotion to formal borders, vivid color juxtapositions, and compositional tensions. I argue that Albizu’s practice constitutes an ongoing concern with a Modernist dialectic and ideals about subjective transformation in a postmodern world of mass culture, a message she conveyed through the material and experiential borders of the canvas. As an avowed formalist and Modernist existing between the postcolonial and postmodern worlds of San Juan and New York City, her work merits formal scrutiny. This paper will add to the diverse histories of Abstract Expressionism and mid-century Modernisms across the Americas while shedding light on an important post-war historical moment and artistic impulse that held on to anti-commercial values in an all-encompassing consumerist world.

Illustrating papyrus in Ancient Egypt

Illustrated papyruses from Ancient Egypt have survived across millennia, depicting with vivid colors numerous stories and practices from a distant past. We have investigated a series of illustrated papyruses from Champollion’s private collection showing scenes from the Book of the Dead, a document essential to prepare for the afterlife. The nature of the different pigments and their distribution are revealed by combining optical microscopy, Raman spectroscopy, and synchrotron X-ray powder diffraction and fluorescence. The standardized three-step process from the New Kingdom period was used, comprising a preparatory drawing made of red hematite, a coloring step using pigments from the Egyptian palette, and a final black contour drawn with a carbon-based ink. Interestingly, specific pigment mixes were deliberately chosen to obtain different shades. In some parts, the final contour significantly differs from the preliminary drawing, revealing the artist’s creativity. These results enhance our knowledge of illustrative practices in Ancient Egypt.

Effect of calcium chloride and gelling agents on the physicochemical and sensory characteristics of sugar-free banana preserves.

Banana preserve is produced by mixing the puree of the fruit with sucrose and organic acids. However, concerns about body esthetics or health reasons have encouraged the search for low-calorie products. Therefore, the objective of this study was to evaluate the effect of calcium chloride (CaCl2), carrageenan gum, and low methoxyl pectin (LM-pectin) on the physicochemical and sensory characteristics of sugar-free banana preserves. By using a central composite rotational design (CCRD) of 2³ + 6 axial points + 4 central points, we obtained 18 formulations that were further tested. Lower CaCl2 concentrations (0.54% to 0.61%) resulted in preserves with lower pH and more vivid color. The increased concentration of LM-pectin (1.40% to 1.64%) resulted in formulations with a yellowish-red hue and with lower moisture, thus, reducing the flavor and purchase intention of the product. Higher concentrations of carrageenan gum (1.04% to 1.15%) decreased the perception of banana preserve aroma. Therefore, concentrations of CaCl2 ranging from 0.54% to 0.61%, carrageenan gum ranging from 0.74% to 0.89% and LM-pectin ranging from 1.40% to 1.64% resulted in sugar-free banana preserves with ideal sweetness and consistency and were, therefore, more acceptable.

Beyond cadmium yellow: CdS photonic crystal pigments with vivid structural colors

This paper reports a method for fabricating CdS photonic crystal pigments through a microfluidic process. The vivid angle-independent structural colors make CdS pigments beyond the traditional cadmium yellow as new pigments towards applications.

Photonic features of blue phase liquid crystals under curved confinement.

Blue phase (BP) liquid crystals represent a fascinating state of soft matter that showcases unique optical and electro-optical properties. Existing between chiral nematic and isotropic phases, BPs are characterized by a three-dimensional cubic lattice structure resulting in selective Bragg reflections of light and consequent vivid structural colors. However, the practical realization of these material systems is hampered by their narrow thermal stability and multi-domain crystalline nature. This feature article provides an overview of the efforts devoted to stabilizing these phases and creating monodomain structures. In particular, it delves into the complex relationship between geometrical confinement, induced curvature, and the structural stability and photonic features of BPs. Understanding the interaction of curved confinement and structural stability of BPs proves crucially important for the integration of these materials into flexible and miniaturized devices. By shedding light on these critical aspects, this feature review aims to highlight the significance of understanding the coupling effects of physical and mechanical forces on the structural stability of these systems, which can pave the way for the development of efficient and practical devices based on BP liquid crystals.

Structural color from pigment-loaded nanostructures.

Color can originate from wavelength-dependence in the absorption of pigments or the scattering of nanostructures. While synthetic colors are dominated by the former, vivid structural colors found in nature have inspired much research on the latter. However, many of the most vibrant colors in nature involve the interactions of structure and pigment. Here, we demonstrate that pigment can be exploited to efficiently create bright structural color at wavelengths outside its absorption band. We created pigment-enhanced Bragg reflectors by sequentially spin-coating layers of poly-vinyl alcohol (PVA) and polystyrene (PS) loaded with β-carotene (BC). With only 10 double layers, we achieved a peak reflectance over 0.8 at 550 nm and normal incidence. A pigment-free multilayer made of the same materials would require 25 double layers to achieve the same reflectance. Further, pigment loading suppressed the Bragg reflector's characteristic iridescence. Using numerical simulations, we further show that similar pigment loadings could significantly expand the gamut of non-iridescent colors addressable by photonic glasses.

Crystalline restacking of 2D-materials from their nanosheets suspensions.

We report here the highly ordered restacking of the layered phosphatoantimonic dielectric materials H3(1-x)M3xSb3P2O14, (where M = Li, Na, K, Rb, Cs and 0 ≤ x ≤ 1), from their nanosheets dispersed in colloidal suspension, induced by a simple pH change using alkaline bases. H3Sb3P2O14 aqueous suspensions are some of the rare examples of colloidal suspensions based on 2D materials exhibiting a lamellar liquid crystalline phase. Because the lamellar period can reach several hundred nanometers, the suspensions show vivid structural colors and because these colors are sensitive to various chemicals, the suspensions can be used as sensors. The structures of the lamellar liquid crystalline phase and the restacked phase have been studied by X-ray scattering (small and wide angle), which has followed the dependence of the lamellar/restacked phase equilibrium on the cation exchange rate, x. The X-ray diffraction pattern of the restacked phase is almost identical to that of the M3Sb3P2O14 crystalline phase, showing that the restacking is highly accurate and avoids the turbostratic disorder of the nanosheets classically observed in nanosheet stacking of other 2D materials. Strikingly, the restacking process exhibits features highly reminiscent of a first-order phase transition, with the existence of a phase coexistence region where both ∼1 nm (interlayer spacing of the restacked phase) and ∼120 nm lamellar periods can be observed simultaneously. Furthermore, this first-order phase transition is well described theoretically by incorporating a Lennard-Jones-type lamellar interaction potential into an entropy-based statistical physics model of the lamellar phase of nanosheets. Our work shows that the precise cation exchange produced at room temperature by a classical neutralization reaction using alkaline bases leads to a crystal-like restacking of the exfoliated free Sb3P2O143- nanosheets from suspension, avoiding the turbostratic disorder typical of van der Waals 2D materials, which is detrimental to the controlled deposition of nanosheets into complex integrated electronic, spintronic, photonic or quantum structures.

Ratiometric colorimetric detection of fluoride ions using a schiff base sensor: enhancing selectivity and sensitivity for naked-eye analysis.

A Schiff base receptor with an active -NH group was designed and synthesized for the selective and sensitive colorimetric detection of inorganic fluoride (F-) ions in an aqueous medium. The sensitivity of the receptor for F- ions was enhanced by the influence of two electron-withdrawing -NO2 groups at ortho and para positions which result in a vivid color change. The receptor underwent a remarkable color change from light yellow to violet, enabling naked-eye detection of F- ions without the need for spectroscopic equipment. To ensure the structural integrity of the synthesized receptors, prominent spectroscopic techniques such as 1H NMR, FTIR, and GCMS analysis were used for characterization. With a limit of detection (LoD) of 0.0996 ppm, a 1 : 2 stoichiometric binding ratio was observed for receptor and F- ions. The binding mechanism confirmed the deprotonation of the -NH group followed by the formation of -HF2, resulting in an intramolecular charge transfer (ICT) transition, which correlates with UV-vis and 1H NMR titration results. In addition, the proposed binding mechanism of F- ion interaction with the receptor was theoretically validated using DFT and TDDFT calculations. Furthermore, as a real-life implementation of the receptor, quantification of the F- ions present in a commercially available mouthwash was demonstrated. To assess the sensitivity performance, a paper-based dip sensor and a solid substrate sensor by functionalizing the receptor on diatomaceous earth were demonstrated. Finally, sensors were built into smartphones that could recognize the red, green, and blue percentages (RGB%) where each parameter defines the intensity of the color, which could also be used as a supplement to the colorimetric investigations.

Postharvest Losses of NOR Tomato Fruit Line MA 131-6-3 Treated by Ethephon and Calcium Carbide

Ethephon and calcium carbide are artificial ripening compounds that are often used to faster fruit ripening during postharvest. These two compounds were induced in non-ripening (NOR) tomato fruit line MA 131-6-3 because it produced endogenous ethylene and lower respiration. This study aimed to determine the effect of ethephon and calcium carbide on postharvest losses of NOR tomatoes for 14 and 28 days after treatment. Exogenous application of 1,500 ppm ethephon and 15 g kg-1 was given to NOR tomato fruit of line MA 131-6-3 and ambient conditions at temperature 28.08±1.80 °C and relative humidity 75.67±2.09%. This experiment was carried out in Sidoarum village, Godean district, Sleman regency, Special Region of Yogyakarta province, Indonesia, in 125 m above sea level. As a result, ethephon can increase fruit rotting. Furthermore, calcium carbide can accelerate metabolism which has an impact on physiological loss in weight, changing color to yellowish (b*), increasing vivid color (chroma), but the color of tomato fruit cannot turn red.
 Keywords: fruit ripening, fruit quality, postharvest, total soluble solids, total titratable acidity

A Continuous Gradient Colloidal Glass.

Colloidal crystals and glasses manipulate light propagation depending on their chemical composition, particle morphology, and mesoscopic structure. This light-matter interaction has been intensely investigated, but a knowledge gap remains for mesostructures comprising a continuous property gradient of the constituting particles. Here, a general synthetic approach to bottom-up fabrication of continuous size gradient colloidal ensembles is introduced. First, the technique synthesizes a dispersion with a specifically designed gradual particle size distribution. Second, self-assembly of this dispersion yields a photonic colloidal glass with a continuous size gradient from top to bottom. Local and bulk characterization methods are used to highlight the significant potential of this mesostructure, resulting in vivid structural colors along, and in superior light scattering across the gradient. The process describes a general pathway to mesoscopic gradients. It can expectedly be transferred to a variety of other particle-based systems where continuous gradients will provide novel physical insights andfunctionalities.

Smartphone-assisted multicolor hypoxanthine sensing for on-site freshness assessment of aquatic products

Hypoxanthine (Hx) has been considered an essential indicator for aquatic products' freshness, especially in the early stage of spoilage. It could generate hydrogen peroxide (H2O2) and uric acid (UA) with the catalyst of xanthine oxidase (XOD). Existed Hx biosensors are only based on H2O2-triggered signal changes or are unsuitable for on-site freshness assessment. Here, we design an on-site Hx sensing method via the detection of both H2O2 and UA by taking advantage of the specific properties of manganese dioxide (MnO2) nanosheets. MnO2 nanosheets could oxidize colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into yellow TMB2+, which can etch gold nanorods (Au NRs) with vivid color changes. However, in the presence of Hx, MnO2 nanosheets were reduced to Mn2+ rapidly by H2O2 and UA, inhibiting the etching step and mediating color changes. The H2O2 and UA meditated strategy exhibits excellent sensitivity toward Hx with a limit of detection (LOD) of 0.378 µM. A WeChat mini program was also constructed to achieve the on-site evaluation and satisfy the special population' requirement. The proposed method has been successfully used to monitor actual sample spoilage under different storage conditions. We expect this method to provide another insight into the on-site freshness assessment of aquatic products.

Taisho-Sanshoku koi have hardly faded skin and show attenuated melanophore sensitivity to adrenaline and melanin-concentrating hormone.

Koi carp, an ornamental fish derived from the common carp Cyprinus carpio (CC), is characterized by beautiful skin color patterns. However, the mechanism that gives rise to the characteristic vivid skin coloration of koi carp has not been clarified. The skin coloration of many teleosts changes in response to differences in the background color. This change in skin coloration is caused by diffusion or aggregation of pigment granules in chromatophores and is regulated mainly by sympathetic nerves and hormones. We hypothesized that there would be some abnormality in the mechanism of skin color regulation in koi carp, which impairs skin color fading in response to background color. We compared the function of melanin-concentrating hormone (MCH), noradrenaline, and adrenaline in CC and Taisho-Sanshoku (TS), a variety of tri-colored koi. In CC acclimated to a white background, the skin color became paler and pigment granules aggregated in melanophores in the scales compared to that in black-acclimated CC. There were no clear differences in skin color or pigment granule aggregation in white- or black-acclimated TS. The expression of mch1 mRNA in the brain was higher in the white-acclimated CC than that in the black-acclimated CC. However, the expression of mch1 mRNA in the brain in the TS did not change in response to the background color. Additionally, plasma MCH levels did not differ between white- and black-acclimated fish in either CC or TS. In vitro experiments showed that noradrenaline induced pigment aggregation in scale melanophores in both CC and TS, whereas adrenaline induced pigment aggregation in the CC but not in the TS. In vitro administration of MCH induced pigment granule aggregation in the CC but not in the TS. However, intraperitoneal injection of MCH resulted in pigment granule aggregation in both CC and TS. Collectively, these results suggest that the weak sensitivity of scale melanophores to MCH and adrenaline might be responsible for the lack of skin color change in response to background color in the TS.

Bifunctional M13 Phage as Enzyme Container for the Reinforced Colorimetric-Photothermal Dual-Modal Sensing of Ochratoxin A.

"Point of care" (POC) methods without expensive instruments and special technicians are greatly needed for high-throughput analysis of mycotoxins. In comparison, the most widely used screening method of the conventional enzyme-linked immunosorbent assay (ELISA) confronts low sensitivity and harmful competing antigens. Herein, we develop a plasmonic-photothermal ELISA that allows precise readout by color-temperature dual-modal signals based on enzymatic reaction-induced AuNP aggregation for highly sensitive detection of ochratoxin A (OTA). The bifunctional M13 phage carrying OTA that mimics the mimotope on the end of p3 proteins and abundant biotin molecules on the major p8 proteins is adopted as an eco-friendly competing antigen and enzyme container for amplifying the signal intensity. Under optimal conditions, both colorimetric and photothermal signals enable good dynamic linearity for quantitative OTA detection with the limits of detection at 12.1 and 8.6 pg mL-1, respectively. Additionally, the proposed ELISA was adapted to visual determination with a cutoff limit of 78 pg mL-1 according to a vivid color change from deep blue to red. The recoveries of OTA-spiked corn samples indicate the high accuracy and robustness of the proposed method. In conclusion, our proposed strategy provides a promising method for eco-friendly and sensitive POC screening of OTA. Moreover, it can be easily applied to other analytes by changing the involved specific mimotope sequence.

A sensitive detection approach for Cu(II) ions in water samples using a solid-state chemical sensor

ABSTRACT We describe the creation of a solid-state optical sensor that is quick to respond, sensitive, and reliable for detecting and determining Cu(II) ions in both natural and wastewater sources. The solid-state template was prepared with mesoporous silica nanospheres of capacious porosity, high surface area, and uniform surface morphology. N,N’-bis(3-carboxysalcylidene)-4-chloro-1,2-phenylenediamine (CSCPD), a chromoionophoric probe with exclusive ion-selectivity and sensitivity for Cu(II), is created for use in naked-eye colorimetric detection. The mesoporous silica nanospheres (MSNs) template displayed several diffusible sites for the uniform anchoring of the CSCPD probe molecules, which serve as a colorimetric ion sensor for the naked eye. The surface profile and structure of the MSNs and the CSCPD sensor materials are studied using BET/BJH, XPS, FESEM, p-XRD, and HR-TEM analysis. With various concentrations of Cu(II), the CSCPD probe-anchored MSNs material reciprocates a vivid visual colour shift from an initial pale yellow colour to green with a reaction period of around one minute. In addition, the MSNs are simply covered with probe molecules as part of the sensor production process. The certified limits of detection for Cu(II) ions for the proposed CSCPD sensor is 1.57 ppb (2.48 × 10−8 M). The suggested CSCPD sensor is dual-functional in that it may be used as a concentrator to recover ultra-trace quantities of Cu(II) ions as well as an effective ion-sensing device.

Mie Resonances Enabled Subtractive Structural Colors with Low-Index-Contrast Silicon Metasurfaces.

All-dielectric structural colors are attracting increasing attention due to their great potential for various applications in display devices, imaging security certification, optical data storage, and so on. However, it remains a great challenge to achieve vivid structural colors with low-aspect-ratio silicon nanostructures directly on a silicon substrate, which is highly desirable for future integrated optoelectronic devices. The main obstacle comes from the difficulty in achieving strong Mie resonances by Si nanostructures on low-index-contrast substrates. Here, we demonstrate a generic principle to create vivid bright field structural colors by using silicon nanopillars directly on top of the silicon substrate. Complementary colors across the full visible spectrum are achieved as a result of the enhanced absorption due to Mie resonances. It is shown that the color saturation increases with the increasing of the nanopillar height. Remarkably, blue and black colors are generated by trapezoid nanopillar arrays as a result of the absorption at long wavelengths or all visible wavelengths. Our strategy provides a powerful scheme for accelerating the integrated optoelectronic applications in nanoscale color printing, imaging, and displays.

Dual Responsive Dependent Background Color Based on Thermochromic 1D Photonic Crystal Multilayer Films.

In this paper, we present dual responsive one-dimensional (1D) photonic crystal (PC) multilayer films that utilize a high-humidity environment and temperature. Dual responsive 1D PC multilayer films are fabricated on precoated thermochromic film by sequential alternate layer deposition of photo-crosslinkable poly(2-vinylnaphthalene-co-benzophenone acrylate) (P(2VN-co-BPA)) as a high refractive index polymer, and poly(4-vinylpyrollidone-co-benzophenone acrylate) P(4VP-co-BPA) as a low refractive index polymer. The thermochromic film shows a vivid color transition from black to white at 28 °C. Three different colors of thermochromic 1D PC multilayer films are prepared by thickness modulation of P(4VP-co-BPA) layers, and the films on a black background exhibit visible spectrum color only in a high-humidity environment (over 90% relative humidity (RH)). For the three films placed on a hands display, three different composite colors are synthesized by the reflection of light, including yellow, magenta, and cyan, due to the changing of backgrounds from black to white with temperature. Additionally, the films show remarkable color transitions with reliable reversibility. The films can be applied as anti-counterfeiting labels and can be used for smart decoration films. To the best of our knowledge, this is the first report of dual response colorimetric films that change color in various ways depending on temperature and humidity changes, and we believe that it can be applied to various applications.

Behind the Scenes of Anthocyanins—From the Health Benefits to Potential Applications in Food, Pharmaceutical and Cosmetic Fields

Anthocyanins are widespread and biologically active water-soluble phenolic pigments responsible for a wide range of vivid colours, from red (acidic conditions) to purplish blue (basic conditions), present in fruits, vegetables, and coloured grains. The pigments' stability and colours are influenced mainly by pH but also by structure, temperature, and light. The colour-stabilizing mechanisms of plants are determined by inter- and intramolecular co-pigmentation and metal complexation, driven by van der Waals, π-π stacking, hydrogen bonding, and metal-ligand interactions. This group of flavonoids is well-known to have potent anti-inflammatory and antioxidant effects, which explains the biological effects associated with them. Therefore, this review provides an overview of the role of anthocyanins as natural colorants, showing they are less harmful than conventional colorants, with several technological potential applications in different industrial fields, namely in the textile and food industries, as well as in the development of photosensitizers for dye-sensitized solar cells, as new photosensitizers in photodynamic therapy, pharmaceuticals, and in the cosmetic industry, mainly on the formulation of skin care formulations, sunscreen filters, nail colorants, skin & hair cleansing products, amongst others. In addition, we will unveil some of the latest studies about the health benefits of anthocyanins, mainly focusing on the protection against the most prevalent human diseases mediated by oxidative stress, namely cardiovascular and neurodegenerative diseases, cancer, and diabetes. The contribution of anthocyanins to visual health is also very relevant and will be briefly explored.

Daytime Sub-Ambient Radiative Cooling with Vivid Structural Colors Mediated by Coupled Nanocavities.

Daytime radiative cooling is a promising passive cooling technology for combating global warming. Existing daytime radiative coolers usually show whitish colors due to their high broadband solar reflectivity, which is not suitable for aesthetic demands and effective display. It is challenging to produce high-cooling performance materials with vivid colors because colors are often produced by the absorption of visible light, decreasing net cooling power. In this work, we design a series of colorful multilayered radiative coolers (CMRCs) consisting of an optimized selective emitter for cooling and coupled nanocavities for structural coloration, which can successfully delicately balance the trade-off between the chromaticity and cooling performance. By judiciously designing the geometric parameters and manipulating the coupling effect inside the coupled nanocavities, our coolers show sub-ambient cooling performance and a larger color gamut (occupying 17.7% sRGB area) than reported ones. We further fabricate CMRCs and demonstrate that they have temperature drops of 3.4-4.4 °C on average based on outdoor experiments. These CMRCs are promising in thermal management of electronic/optoelectronic devices and outdoor facilities.

Haze Removal Method for Efficient Visualization of Remotely Sensed Satellite Images

Abstract: Images captured in foggy weather conditions often suffer from poor visibility, which will create a lot of impacts on the outdoor computer vision systems, such as video surveillance, intelligent transportation assistance system, remote sensing space cameras and so on. In such situations, traditional visibility restoration approaches usually cannot adequately restore images due to poor estimation of haze thickness and the persistence of color cast problems. In our work, we propose a visibility restoration approach to effectively solve inadequate haze thickness estimation and alleviate color cast problems. By doing so, a high-quality image with clear visibility and vivid color can be generated to improve the visibility of single input image (with fog or haze), as well as the image’s details. Our approach stems from two important statistical observations about haze-free images and the haze itself. First, Wavelet decomposition is applied and LUM Filter is applied on the decomposed image. Finally, we can get the dehazed output.

Partition of bioactive components from red pitaya fruit (Hylocereus polyrhizus) peels into different fractions using supercritical fluid fractionation technology

The pitaya peel powder was mixed with 50% ethanol solution at a ratio of 1:10 (w/v) for 24 h to obtain the pitaya peel ethanol extract (E). The extract was further fractionated with supercritical carbon dioxide (SC–CO2) under the operating conditions: temperature 40 °C and pressure of 30, 25, 20 or 10 MPa into R, F1, F2 or F3 fractions, respectively. Our results confirmed SC-CO2 fractionation significantly influenced the distribution of phenolic compounds, polysaccharides and betalains in fractions and thus affected their physico-chemical properties. Bioactive compounds majorly distributed in F1; consequently, DPPH and ABTS radicals scavenging activities of F1 are higher than those of other fractions. The IC50 values of DPPH and ABTS scavenging ability were 0.78 mg/mL and 0.69 mg/mL for F1 fraction, respectively. Linear structure model analysis showed that the scavenging activities of the both free radicals were positively related to phenolic compounds and polysaccharide components. The strong red-orange color spectrum of E was simultaneously fractionated into the red-orange color F1, the bright red color of F2 and F3 and the vivid orange color of R.