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This study aimed to estimate the number of distinct tooth colors using a large dataset of in-vivo CIELAB measurements. It further assessed the coverage error (CE) and coverage error percentage (CEP) of commonly used shade guides and determined the number of shades needed for an ideal guide, using the Euclidean distance (ΔEab) and thresholds for clinical perceptibility (PT) and acceptability (AT) as evaluation criteria. A total of 8153 untreated maxillary and mandibular anterior teeth were measured in vivo using calibrated dental photography. Cardinality was applied to determine the number of unique natural tooth colors. The CE and CEP were calculated for the Vita Classical and Vita 3D-Master shade guides, while the cardinality method was also used to estimate the number of shades required to adequately cover the estimated gamut of natural tooth colors. The cardinality analysis revealed 1173 unique natural tooth colors. The CE for the Vita Classical shade guide was 4.1 ΔEab, with a CEP of 75 % beyond AT, while the 3D-Master shade guide had a CE of 3.3 ΔEab and a CEP of 70 % beyond AT. Based on cardinality computation, 92 discrete shades are required to adequately cover the estimated gamut of natural tooth colors with a CE of 1.2 ΔEab and CEP of 0.3 % beyond AT. Cardinality computations estimated 1173 unique tooth colors while 92 discrete shades are estimated for full coverage. Such a number is impractical for physical shade guides, but new digital tools and 3D printing may offer future solutions. Both, the Vita Classical and 3D-Master shade guides do not fully represent the range of natural tooth colors. This study highlights the limitations of existing shade guides and underscores the potential for new developments. [ABSTRACT FROM AUTHOR]

The purpose of the study was to investigate the influence of different tooth-colored substrates and restoration thicknesses on the final color of gingiva-colored resin-based composites (GCRBCs). Five different shades of GCRBCs [light pink (LP), dark pink (DP), orange (Or), brown (Br), and purple (P)] were used to prepare disc-shaped specimens with 2 different thicknesses: 1.0 mm, and 2.0 mm. GCRBC discs (n = 5) were placed over 3 different tooth-colored substrates (ND1, ND5, and ND9) and color parameters were assessed using a spectroradiometer. Color differences (∆E*ab and ∆E00) were calculated using CIELab and CIEDE2000 formulas and compared to 50:50% perceptibility (PT: ∆E*ab = 1.7, ΔE00 = 1.1) and acceptability (AT: ∆E*ab = 3.7, ΔE00 = 2.8) visual thresholds. Color variation data were statistically analyzed using two-way ANOVAs followed by Bonferroni's post hoc tests (a = 05). The ∆E*ab and ΔE00 values of GCRBCs placed over ND9 substrates were significantly higher in the LP-1.0 mm and Or-1.0 mm groups that presented values above AT (p<.001). Regardless of the substrate color and GCRBC thickness applied, ∆E*ab and ΔE00 values below AT were recorded in the gingival color groups of P. Substrate color significantly affected the color differences in the gingival color groups of LP, DP, and Or with a restoration thickness of 1.0 mm (p <.05). Gingival color, restoration thickness, and substrate color influenced the color differences of GCRBCs. When the gingival color was a lighter gingival color, rather than dark purple, the masking ability was decreased, especially with a restoration thickness of 1.0 mm. [ABSTRACT FROM AUTHOR]

Environmentally friendly natural dyes have gained popularity recently because synthetic dyes have negative health effects. Through preliminary phytochemical screening, the work examined the dyeing potential of primary and secondary metabolites of Tunisian lichens. In most of the lichen extracts examined, significant tannins, proteins, carbohydrates, and steroids were present. The dyeing potential was determined by ammonia fermentation (AFM) and boiling water (BWM) methods on wool and fabric. The dyes degraded when exposed to light and heat. Alum, copper sulfate, and iron sulfate were used for the mordanting process. The studied lichen species generated a variety of hues using both techniques, including brown, caramel, purple, olive, green, and yellow. Both approaches revealed a wide variety of colors in all species. On both fabrics, the coloring patterns were depicted. Brighter colors were created by AFM than by BWM. But using BWM, Xanthoria parietina produced stunning purple dyes for textiles. Fabrics that have been mordanted had better sunshine colorfastness. The color shading was finest with an alum mordant. Using an Android application colorimeter, the dyed materials were assessed using CIE Lab* Chroma, Hue, and standard procedures following international standards. There is an alternative to traditional instruments in the form of this smartphone app. Most dyed textiles had very good to exceptional color fastness. In conclusion, phytochemical analysis of Tunisian lichens revealed their potential as suppliers of natural colors that are friendly to the environment. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective Materials and Methods Results Conclusions This study aimed to assess the relative translucency parameter (RTP) of human enamel and dentin and set target RTP values for dental material development. Additionally, it seeks to validate the spectral RTP concept as supplementary quantitative information.Slides of extracted human teeth, 1 and 2 mm thick enamel or dentin slides, were evaluated. RTP was calculated using CIEDE2000 (RTP00) and CIELAB (RTPab) color difference formulas. Spectral RTP (SPECTRAL RTP) curves were also generated from differences between spectral reflectance values obtained against white and black backgrounds. Statistical analyses included multifactorial ANOVAs for each RTP and spectral RTP, and Pearson correlations between RTP and spectral RTP.Significant correlations were observed between the RTP and spectral RTP values (p < 0.001) at all studied wavelengths. RTP00 and RTPab values were significantly different (p < 0.001). Enamel showed more translucency than dentin (p < 0.001), and 1 mm slices were more translucent than 2 mm slices (p < 0.001).Spectral RTP values were influenced by the type of tissue (enamel, dentin), thickness (1 mm, 2 mm), and color difference formula (CIELAB2000, CIELAB). RTP curve values were influenced by tissue type, thickness, and wavelength. Spectral RTP and RTP curve values were correlated. [ABSTRACT FROM AUTHOR]

Currently, the automotive sector is showing increased demands regarding the color of cars in general, but especially the quality and the time of painting, in particular. Companies working in this industry, especially in specialized painting services, must perform work of impeccable quality in the shortest possible time in order to be efficient. Color differences that appear in different areas of the car result from the use of different formulas for obtaining color. These differences can be reduced by using correction factors that are established for the colors in the partial or total painting process of cars. There are several factors that lead to settings that are not verified by the real color and, therefore, contribute to incorrect color results and also to high and unnecessary repair costs. In this study, the authors aimed to optimize the values of the correction factors applicable in the automotive industry, based on a set of 135 measurements performed with a BYK Gardner spectrophotometer, in order to minimize color differences. Through this study, authors have also aimed to find out how the color-identification process can be streamlined with the smallest possible tolerances by optimally adjusting the correction factors and by identifying the factors that influence the color-reading and identification process. A total of 85 pairs of samples were used for the DS1 (data set) and 53 pairs of samples for the DS2 (data set); these samples were used in the visual experiments for testing the performance of two color-differentiation formulas. The first part of the research aimed to investigate the visual perception of the painted cars in terms of differences in brightness, chroma and hue, data that were used to optimize the formulas used for color differences. Finally, authors have estimated the closest color variant to the objective color by optimizing the correction factors and thus achieving the efficiency of the color-identification process and the whole painting-identification process. [ABSTRACT FROM AUTHOR]

In-office teeth bleaching is an esthetic dental procedure performed to whiten teeth. A desensitizing procedure often requires prior in-office bleaching to relieve tooth hypersensitivity. The objective of this study was to evaluate the bleaching efficiency of teeth specimens pre-treated with different desensitizing agents by analyzing the color parameters. A total of 25 bovine specimens were stained and divided into five groups (n = 5). The specimens were pre-treated with GLUMA, ICON, bonding, or fluoride varnish according to the manufacturer's instructions. Subsequently, the samples underwent three consecutive 20 min bleaching sessions using an in-office bleaching product. Color values in the CIE L*, a*, and b* color space were initially recorded, both before any treatment and after each bleaching session. The color difference (ΔE) was then computed. The data were analyzed using SPSS 24.0 software. The color alteration after pre-treatment was analyzed using a one-way ANOVA test, and the color alteration in each bleaching session was compared using a repeated-measure ANOVA test. A one-way ANOVA analysis showed a statistically significant difference in the bleaching efficiency of teeth specimens pre-treated with different desensitizers (p < 0.001). The repeated-measure ANOVA analysis showed no statistically significant difference in additional bleaching sessions (p = 0.133). The ICON and bonding pre-treatment showed the color alteration of teeth specimens before the bleaching procedure. Although the different desensitizer pre-treatments showed significant differences in bleaching efficiency, the differences in color parameters of the teeth specimens at the end of three bleaching sessions were statistically insignificant. Desensitizer pre-treatment influenced the degree of color change during multiple bleaching sessions; however, the outcome of bleaching was not affected by desensitizer pre-treatment. [ABSTRACT FROM AUTHOR]

Banana (Musa x paradisiaca L.) is a lignocellulosic natural fiber that can be processed to produce eco-friendly and biodegradable hybrid fabrics when combined with other fibers. Natural-dyed banana fiber can be utilized in the production of sustainable materials for wearable products, household linens, technical textiles, and apparel. In this study, banana-silk union fabrics, pre-treated with bio-mordant at concentrations of 1%, 2%, 3%, 4%, and 5%, were dyed separately using cochineal insect extract (Dactylopius coccus Costa). To assess the dyeability of the banana-silk union fabric, Anatolian black pine cones (Pinus nigra subsp. pallassiana) were utilized as a bio-mordant, with varying quantities. The CIELab values of the dyeings were measured and compared. Additionally, the chemical composition of the cochineal extract, pinecone mordant, raw fabric, and selected dyed fabrics was analyzed using Fourier Transform Infrared (FTIR) spectroscopy. The washing, light, and rubbing fastness properties of the dyed banana-silk union fabrics were also evaluated and compared. This study developed a method for weaving union fabric by blending two distinct natural yarns, namely banana and silk, to reduce dependence on a single fiber and promote the utilization of agricultural waste. [ABSTRACT FROM AUTHOR]

Paprika, obtained from dried red pepper (C. annuum), is valued for its characteristic colour and flavour. Its carotenoid content, which is important for both sensory and nutritional quality, varies depending on several factors (agronomic conditions and technological treatment with special attention to the drying methods) that influence the colour and antioxidant capacity of the samples. This study investigated the effect of an accelerated thermal treatment (80 °C for 8 h) applied to evaluate the oxidative stability of the carotenoids and the colour of ground paprika depending on its origin (Peru or China). Changes in quality parameters (ASTA index and CIELAB colour), carotenoid content and profile (HPLC-DAD) and lipophilic antioxidant capacity (FRAP and ABTS•+ methods) were evaluated. Untreated Chinese samples had 30% more total carotenoids than Peruvian samples, but this was not reflected in ASTA units, indicating that at least a 50% carotenoid variation is required for significant differences. Treatment resulted in a carotenoid loss of 70% in Peruvian and 30% in Chinese samples, with changes in total carotenoids correlating positively with antioxidant capacity. Both origins had similar carotenoid profiles, with β-carotene being the predominant carotenoid, while distinct contents were observed between the origins. The higher content of esterified carotenoids in Chinese peppers resulted in better thermal stability. The results highlight the necessity for tailored production processes to maintain nutritional integrity and antioxidant capacity. [ABSTRACT FROM AUTHOR]

Ensuring the limited exposure of both patients and medical professionals to radiation during examinations is paramount. One effective approach is the utilization of a film dosimeter that is not only efficient but also easy to carry. In this research, we employed polyvinyl alcohol/nitro blue tetrazolium (PVA/NBT) with varying concentrations of NBT dye (ranging from 0.015 to 0.3 g) to identify the most optimal concentration. These films were subjected to low doses of gamma rays (8, 25, 55 and 96 mGy) emitted from 3 Cs-137 sources. XRF analysis confirmed the effectiveness of the preparation method used, and the NBT salt exhibited excellent solubility (R² = 0.93). The films exhibited an increasing yellow hue as the concentration of NBT dye rose. Following irradiation, they took on a yellowish-brown tint, intensifying with higher gamma doses. PVA/NBT films, when stored in the dark, demonstrated good stability for 30 days post-irradiation. Analysis using ImageJ software unveiled that the relative density of the red color heightened proportionally with the concentration of NBT dye. XRD patterns showcased the clarity of structural rearrangements occurring after irradiation with high NBT concentrations. Two distinct peaks were registered at 2θ = 20.12 and 40.94 °, which shifted to 2θ = 19.74 and 41.30 ° post-gamma irradiation. The CIELab system study and K/S color strength indicated that increasing the NBT dye concentration led to a linear rise in color strength with escalating low gamma doses. Through a comprehensive assessment, it is concluded that PVA/NBT film can be effectively employed as a dosimeter for low gamma doses in diagnostic radiology. [ABSTRACT FROM AUTHOR]

This study investigated the potential of petal colorimetric data to classify vase life stages in cut lisianthus flowers (Eustoma grandiflorum). We analyzed the changes in the petal color space over time, focusing on the b* value as an indicator of senescence due to increasing yellowing caused by copigmentation. A comparative analysis was conducted between two cultivation methods: soil (S) and hydroponic (H) cultivation. The objective was to evaluate the performance of machine learning models trained to classify vase life stages based on petal color data. Automated machine learning models exhibited better performance in H-cultivated cut flowers, effectively distinguishing days within the vase life stages from Days 1 to 14 for H cultivation. Cut flowers cultivated under S conditions showed less variation in the color space from Days 1 to 9, maintaining a relatively uniform color range. This made it more difficult to distinguish the vase life stages compared to H cultivation. These findings demonstrate that petal color metrics can serve as reliable indicators of cut flower senescence and potentially facilitate nondestructive methods for classifying vase life stages. This technology holds promise for wider applications in the floriculture industry, improving quality control, and extending the vase life of various cut-flower crops. [ABSTRACT FROM AUTHOR]

Lateral flow assay (LFA) color signal quantification methods were developed by utilizing both International Commission on Illumination (CIE) LAB (CIELAB) color space and grayscale intensity differences. The CIELAB image processing procedure included calibration, test, control band detection, and color difference calculation, which can minimize the noise from the background. The LFA platform showcases its ability to accurately discern relevant colorimetric signals. The rising occurrence of infectious outbreaks from foodborne pathogens like Salmonella typhimurium presents significant economic, healthcare, and public health risks. The study introduces an aptamer-based lateral flow (ABLF) platform by using inkjet printing for specially detecting S. typhimurium. The ABLF utilized gold-decorated polystyrene microparticles, functionalized with specific S. typhimurium aptamers (Ps-AuNPs-ssDNA). The platform demonstrates a detection limit of 102 CFU mL−1 in buffer solutions and 103 CFU mL−1 in romaine lettuce tests. Furthermore, it sustained performance for over 8 weeks at room temperature. The ABLF platform and analysis methods are expected to effectively resolve the low-sensitivity problems of the former LFA systems and to bridge the gap between lab-scale platforms to market-ready solutions by offering a simple, cost-effective, and consistent approach to detecting foodborne pathogens in real samples. [ABSTRACT FROM AUTHOR]

In this work, studies were performed on oxidative stability by determining the transmittance spectra, the components and trichomatic coordinates, and the color differences for grape seed oils (GSO) subjected to a forced oxidation treatment at temperatures of 100 °C and 120 °C, for 4, 8 and 10 h. For this purpose, a constant airflow of 30 L/min was used. GSO was also subjected to flammability tests on a heated cylindrical surface to determine the lowest temperature at which this oil ignites, correlated with the highest temperature at which the oil does not ignite. According to the results, these temperatures are 475 °C and 470 °C, respectively. At these temperatures, the tested oils were darker in color than the reference oil, with the L* parameter having lower values (91.53 and 89.56, respectively). In addition, the correlation coefficients between the evaluated parameters were significant (p ≤ 0.05). [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the staining sensitivity and surface changes in recent composite resins (Herculite Ultra XRV (Kerr, Bolzano, Italy), G-ænial A'CHORD (GC Corp, Tokyo, Japan), and Omnichroma (Yamaguchi, Japan)) when exposed to common beverages such as coffee, red wine, and Coca-Cola. A total of 60 disk-shaped specimens were prepared from three different resin composites (n = 20 each). The specimens were exposed to coffee, red wine, and Coca-Cola for 10 days. Color measurements were taken using a spectrophotometer, and surface morphology and elemental composition were analyzed using SEM and EDS. The SEM and EDS analyses revealed significant changes in the surface morphology and elemental composition of the composites after immersion. Coffee and wine caused significant surface degradation, whereas Coca-Cola resulted in the greatest degree of surface and elemental variations. Color changes (ΔE = 4 ± 0.52) were most notable in Coca-Cola for Herculite Ultra XRV (Kerr, Italy), in red wine for G-ænial A'CHORD (GC Corp, Japan) (ΔE = 12.51 ± 0.38), and in coffee for Omnichroma (Yamaguchi, Japan) (ΔE = 10.85 ± 1.03). The tested beverages significantly affected both the surface condition and the chemical composition of the resin at the surface level. These findings highlight the importance of understanding the effects of common dietary beverages on dental composites. [ABSTRACT FROM AUTHOR]

This study investigates the potential of Australian Traditional foods as novel sources of natural colourants for food applications, employing untargeted metabolomics and chemometrics. Two native species were analysed: Davidson plum and native currant. The species were quantitatively assessed for colour properties using the CIELAB colour system in conjunction with Ultra Performance Liquid Chromatography-Quadrupole Time of Flight Tandem Mass Spectrometry (UPLC-Q-ToF-MS/MS). The results highlight diverse phenolic, flavonoid, and significant anthocyanin levels in Davidson plum and native currant, contributing to their robust red hues, comparable to commercial blueberry standards. Davidson plum and native currant exhibited high phenolic, flavonoid, and anthocyanin levels, contributing to vibrant red hues and significant bioactivity. Compared to blueberry, these species showed greater redness (a*) and chroma. Native currant demonstrated the highest phenolic content (146.73 mg g−1), anthocyanin content (14.48 mg g−1), and antioxidant activity (95.48 μmol Trolox equivalents/g). The chemometric analysis identified 46 key pigment metabolites, including anthocyanins and flavonoids, directly correlating to observed colour properties. UPLC-Q-ToF-MS/MS combined with CIELAB colourimetry facilitated pigment identification and colour analysis. These findings position Davidson plum and native currant as promising natural food colourants and functional ingredients. Additionally, the study underscores the efficacy of integrating chemometric analysis with CIELAB and UPLC-Q-ToF-MS/MS methodologies for pinpointing specific metabolites that influence the colour properties of these Traditional foods. This approach facilitates a deeper understanding of how indigenous Australian bushfoods can be innovatively incorporated into the food industry, aligning with consumer demand for natural and sustainable food options.

Objetivo: El objetivo fue evaluar el color de incisivos centrales superiores (1.1), en pacientes de entre 20 y 30 años, en el Hospital Odontológico Universitario de la FOUBA Métodos: Participaron 125 sujetos (84,25% mujeres) de entre 21 y 30 años, con un promedio (ds) de edad de 24,36 (2,20) - 030/2019 CETICAFOUBA, se incluyeron sujetos que hubieran consentido participar y cuyo 1.1 cumpliera con los criterios de inclusión. Luego de una profilaxis en la superficie bucal, un observador registró el color en el tercio medio -en escala VITA CLASSIC y según CieL*a*b*- con VITA Easyshade V (Zahnfabrikn) calibrado antes de cada determinación y empleado según las instrucciones del fabricante. Resultados: VITA CLASSIC %(IC95%): A1: 47,20 (38,67-55,91), luego A2: 19,20 (13,26-26,98), B2: 13,60 (8,67- 20,71), y B1: 8,80 (4,99-15,07), y finalmente D2: 3,20 (1,26-7,94), C2: 2,40 (0,82-6,82), A3, C3 y B3: 1,60 (0,45-5,65) y A3,5: 0,8 (0,14-4,4). En el marco de las coordenadas CieL*a*b* los valores encontrados fueron: media (ds), min-max : L*: 77,56 (5,76), 63,5-86,6; a*: - 1,18 (1,42), -3,1-2,1; b*: 13,08 (5,05), 4,9- 23,9. Conclusiones: En el marco de este estudio, el color más frecuente en 1.1 entre sujetos de entre 20 y 30 años fue el A1 de la escala VITA CLASSIC.

Dental multilayer zirconia ceramics are attractive materials for restorative dentistry because they offer significant esthetic advantages over monolithic, white, or monocolored zirconia. They enable anatomical adjustments in dental prostheses, making them more similar to natural teeth. New categories of dental ceramics have been developed using varying translucency and color within the same piece to meet esthetic requirements. This technique employs zirconia with different yttria (Y2O3) contents to achieve varying levels of translucency. This study investigated two types of dental ceramics based on multilayer zirconia, correlating their mechanical properties, translucency, and color variations concerning their application in dental prostheses. Two types of multilayer zirconia pre-sintered blocks with different Y2O3 content were examined: 1) blocks with a Y2O3 gradient chemical composition between 3 mol.% and 4 mol.%, named M3-4YSZ; 2) blocks with a Y2O3 gradient chemical composition between 4 mol.% and 5 mol.%, named as M4-5YSZ. Samples were cut in cross-section to separate the layers based on Y2O3 content and color and were then sintered at 1530 °C for 2 h. The sintered samples were characterized by relative density, crystalline phases, microstructure, Vickers hardness, fracture toughness (KIC), and optical properties (color and contrast ratio). Fully dense ceramics were obtained after sintering. Layers containing a greater amount of Y2O3 in the zirconia matrix have a higher content of the ZrO2 cubic phase, while layers with a lower content of Y2O3 in the matrix are predominantly tetragonal ZrO2. No statistical variation in hardness was observed depending on the layers of the material. However, fracture toughness values showed significant statistical variations, with an increase in the tetragonal phase content responsible for the increase in fracture toughness. KIC in M3-4YSZ samples varied between 3.63 and 7.73 MPa.m1/2, while M4-5YSZ samples ranged from 2.70 to 5.65 MPa.m1/2. The smooth and gradual variations in color and translucency observed between the layers of the two groups of dental ceramics studied indicate stability and homogeneity between the layers, contributing significantly to esthetic effects in dental applications.

Abstract Nowadays, secondary raw materials (SRM) obtained from plant matrices are of great interest for circular economy, suitable for sustainable measures to reduce environmental impact. This work focused on the extraction, characterization and quantification of compounds obtained from leaves and fruits of the Sicilian sumac, Rhus coriaria L. and their application as natural dyes on textile fibres. Extractions were performed with Extractor Naviglio®, maceration and ultrasound assisted methods and food-grade solvents (aqueous and hydroalcoholic) to evaluate the yields for dye compounds. The presence of colouring molecules was evaluated by UV–Vis spectrophotometer, and the extracts selected for colouring were quantified and characterized by LC–MS. The results showed that Extractor Naviglio® achieved the best extraction yield, and the ethanol–water mixture extracts had a higher amount of total phenolic compounds (TPC) and a higher content of total colouring compounds (TCC). These extracts were selected for subsequent applications as dyes for linen, cotton and wool. The chemical profile of selected extracts was rich in compounds such as gallotannin and anthocyanin class. Fibre dyeing was verified by recording CIELAB colouring coordinates. The results suggest that the dyes obtained from R. coriaria can be of great interest for artisanal and industrial processes, in accordance with environmental sustainability.

Color degradation is a pressing issue in various fields like food and medicine packaging, as well as printed materials, leading to a loss or distortion of vital information. Therefore, understanding how the color of package prints evolves over time is essential for product quality assessment and effective product life cycle management. This study focuses on investigating color changes in prints on blister foils, widely used in the medicine and packaging industries. To assess fading characteristics, samples printed via the gravure process have been exposed to a Xenon Test Chamber (B‐SUN). Spectrophotometric measurements of the prints have been conducted using a spectroradiometer, and the data have been analyzed using principal component analysis (PCA). The fading nature of cyan and black prints aligns with Type IV, while magenta and yellow prints correspond to Type II, as described by Giles. Notably, cyan and black inks demonstrated resistance toward fading at the end of the exposure, with a minor exception. The investigation involved curve fitting, revealing a consistent first‐order kinetic model governing fading rates throughout the exposure time. High R2 values (0.96–0.99) and low root means square error values (0.02–0.08) are observed across all cases. While color fading involves diverse kinetics, the fading rate consistently adheres to a singular first‐order kinetic path. The study highlights that yellow ink is most sensitive to light, followed by magenta ink. These findings offer valuable insights for optimizing packaging materials and ensuring product quality in industries reliant on printed materials. By mitigating color degradation, manufacturers can enhance the longevity and appeal of their products, reinforcing consumer trust and satisfaction. Furthermore, the effective utilization of PCA as a data analysis tool offers a valuable approach for future investigations in color science and related fields. [ABSTRACT FROM AUTHOR]

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Nowadays, secondary raw materials (SRM) obtained from plant matrices are of great interest for circular economy, suitable for sustainable measures to reduce environmental impact. This work focused on the extraction, characterization and quantification of compounds obtained from leaves and fruits of the Sicilian sumac, Rhus coriaria L. and their application as natural dyes on textile fibres. Extractions were performed with Extractor Naviglio®, maceration and ultrasound assisted methods and food-grade solvents (aqueous and hydroalcoholic) to evaluate the yields for dye compounds. The presence of colouring molecules was evaluated by UV–Vis spectrophotometer, and the extracts selected for colouring were quantified and characterized by LC–MS. The results showed that Extractor Naviglio® achieved the best extraction yield, and the ethanol–water mixture extracts had a higher amount of total phenolic compounds (TPC) and a higher content of total colouring compounds (TCC). These extracts were selected for subsequent applications as dyes for linen, cotton and wool. The chemical profile of selected extracts was rich in compounds such as gallotannin and anthocyanin class. Fibre dyeing was verified by recording CIELAB colouring coordinates. The results suggest that the dyes obtained from R. coriaria can be of great interest for artisanal and industrial processes, in accordance with environmental sustainability. [ABSTRACT FROM AUTHOR]

Paprika, obtained from dried red pepper (C. annuum), is valued for its characteristic colour and flavour. Its carotenoid content, which is important for both sensory and nutritional quality, varies depending on several factors (agronomic conditions and technological treatment with special attention to the drying methods) that influence the colour and antioxidant capacity of the samples. This study investigated the effect of an accelerated thermal treatment (80 °C for 8 h) applied to evaluate the oxidative stability of the carotenoids and the colour of ground paprika depending on its origin (Peru or China). Changes in quality parameters (ASTA index and CIELAB colour), carotenoid content and profile (HPLC-DAD) and lipophilic antioxidant capacity (FRAP and ABTS•+ methods) were evaluated. Untreated Chinese samples had 30% more total carotenoids than Peruvian samples, but this was not reflected in ASTA units, indicating that at least a 50% carotenoid variation is required for significant differences. Treatment resulted in a carotenoid loss of 70% in Peruvian and 30% in Chinese samples, with changes in total carotenoids correlating positively with antioxidant capacity. Both origins had similar carotenoid profiles, with β-carotene being the predominant carotenoid, while distinct contents were observed between the origins. The higher content of esterified carotenoids in Chinese peppers resulted in better thermal stability. The results highlight the necessity for tailored production processes to maintain nutritional integrity and antioxidant capacity.

Data visualization is essential to discover patterns and anomalies in large high-dimensional datasets. New dimensionality reduction techniques have thus been developed for visualizing omics data, in particular from single-cell studies. However, jointly showing several types of data, for example, single-cell expression and gene networks, remains a challenge. Here, we present 'U-CIE, a visualization method that encodes arbitrary high-dimensional data as colors using a combination of dimensionality reduction and the CIELAB color space to retain the original structure to the extent possible. U-CIE first uses UMAP to reduce high-dimensional data to three dimensions, partially preserving distances between entities. Next, it embeds the resulting three-dimensional representation within the CIELAB color space. This color model was designed to be perceptually uniform, meaning that the Euclidean distance between any two points should correspond to their relative perceptual difference. Therefore, the combination of UMAP and CIELAB thus results in a color encoding that captures much of the structure of the original high-dimensional data. We illustrate its broad applicability by visualizing single-cell data on a protein network and metagenomic data on a world map and on scatter plots.

In physical environments and cultural landscapes, we most often deal not with separate colors, but with color combinations. When choosing a color, we usually try to "fit" it into a preexisting color context, making the new color combination harmonious. Yet are the "laws" of color harmony fundamental to our shared cognitive architecture, or are they cultural products that vary from country to country? To answer these questions we conducted an experiment with 599 participants aged 18 to 76 from eight different countries, including Algeria (MA = 26.2 years; SD = 8.8; 49 men, 26 women), Belarus (MA = 19.8 years; SD = 9.1; 19 men, 63 women), Italy (MA = 29.0 years; SD = 12.8; 23 men, 67 women), Mexico (MA = 20.0 years; SD = 7.0; 34 men, 23 women), Nigeria (MA = 34.7 years; SD = 10.5; 29 men, 32 women), Russia (MA = 24.6 years; SD = 6.3; 17 men, 72 women), Saudi Arabia (MA = 24.5 years; SD = 8.6; 28 men, 38 women), and Chile (MA = 34.3 years; SD = 15.1; 35 men, 43 women). To create experimental stimuli, we used 10 color combinations composed by the Russian avant-garde artist Mikhail Matyushin and his disciples for the Reference Book of Color (1932) based on shades that were typical in architectural design—yellow ochre, light umber, light ochre, and burnt umber. We removed the "intermediary" linking color from each of the selected color triads and asked participants to adjust the color of this band according to their liking. Mapping 2995 color choices into CIELAB and CIELCh color space to identify their chromatic characteristics (hue, lightness, and chroma), we demonstrate graphically that color triads in different cultures have a different "geometry" in CIELAB color space and on the color circle. We conclude that the revealed patterns of these relationships reflect cross-cultural "shifts" in human perception of color harmony. The analysis presented in this paper will facilitate opportunities for architects, designers, and other color professionals to create culturally specific harmonic color combinations in urban environments. [ABSTRACT FROM AUTHOR]

Statement of Problem: The Vita Toothguide 3D‐Master (Vita Zahnfabrik) is considered the dental shade guide in which the three dimensions of color – lightness, hue, and chroma – are most well‐ordered in the CIELAB color space. No research has yet explored how well the Vita Toothguide 3D‐Master is ordered in the 3D color space by recording color coordinates in vivo. Purpose: To evaluate the spatial color distribution of the Vita Toothguide 3D‐Master's lightness, chroma, and hue groups and its 26 physical shade tabs. Materials and Methods: The dental color (L*, C*, h°, a*, and b* color coordinates) of a healthy maxillary central incisor was recorded for 1361 participants (aged between 18 and 89 years) using a Vita Easyshade Compact spectrophotometer (Vita Zahnfabrik). The R 2.7.2. statistics program was used to create the visual representations. Results: The five lightness levels are those that are best distributed in the color space, in relation to the L* coordinates, followed by the chroma group and, finally, the hue group. The 5M1, 5M2, and 5M3 physical shade tabs are situated at a greater distance apart from the other tabs in the color space. Conclusions: The Vita Toothguide 3D‐Master's 26 physical shade tabs are satisfactorily distributed in three‐dimensional space, although strict mathematical criteria are not followed. The natural dental shades that fall lower on the lightness scale are the most poorly represented by the physical shade tabs. Clinical Implications: Darker teeth are poorly represented by the Vita Toothguide 3D‐Master's physical shade tabs. The spatial distribution of dental shade guides needs to be improved to ensure they provide homogeneous coverage of the entire chromatic spectrum corresponding to natural teeth. This would help reduce the errors inherent to the subjective visual color selection process. [ABSTRACT FROM AUTHOR]

Andrographis paniculata (Burm.f.) Wall.ex Nees is a standing out medicinal herb. It contains a large quantity of andrographolide and wildly used a traditional herb in many countries. Andrographolide is found in all part of the plant. However, those part are different in color, active compound content and antioxidant activity. Even though, there are several methods to determine andrographolide and antioxidant. They are chemical involved, complicated and time consuming. Therefore, the objective of this study was to develop estimation method of andrograhpholide content and antioxidant activities by CIE color parameters. The result showed that range of CIE color parameters of andrographolide sample were broad with range from light greyish yellow-green to greyish dark green. Antioxidant activity was barely correlated with colors. However, andrographolide content showed moderate correlation with colors. Dark green andrographis herb contain higher andrographolide than light greyish yellow-green one. Furthermore, andrographolide content could be numerical estimated by CIELab and CIELCh color parameters. The developed estimating method were easy, rapid and no chemical involved. [ABSTRACT FROM AUTHOR]

This study has developed and optimized a machine learning model to accurately predict the final colors of CAD-CAM ceramics and determine their required minimum thicknesses to cover different clinical backgrounds. A total of 120 ceramic specimens (2 mm, 1 mm and 0.5 mm thickness; n = 10) of four CAD-CAM ceramics - IPS e.max, IPS ZirCAD, Upcera Li CAD and Upcera TT CAD - were studied. The CIELab coordinates (L*, a* and b*) of each specimen were obtained over seven different clinical backgrounds (A1, A2, A3.5, ND2, ND7, cobalt-chromium alloy (CC) and medium precious alloy (MPA)) using a digital spectrophotometer. The color difference (ΔE) and lightness difference (ΔL) results were submitted to 39 different models. The prediction results from the top-performing models were used to develop a fusion model via the Stacking integrated learning method for best-fitting prediction. The SHapley Additive exPlanation (SHAP) was performed to interpret the feature importance. The fusion model, which combined the ExtraTreesRegressor (ET) and XGBRegressor (XGB) models, demonstrated minimal prediction errors (R2 = 0.9) in the external testing sets. Among the investigated variables, thickness and background colors (CC and MPA) majorly influenced the final color of restoration. To achieve perfect aesthetic restoration (ΔE<2.6), at least 1.9 mm IPS ZirCAD or 1.6 mm Upcera TT CAD were required to cover the CC background, while two tested glass-ceramics did not meet the requirements even with thicknesses over 2 mm. The fusion model provided a promising tool for automate decision-making in material selection with minimal thickness over various clinical background. [Display omitted] • Fusion Machine Learning (ML) model accurately predicts the final color of CAD-CAM restoration. • Ceramic thickness is the most influential factor in predicting the desired color outcome. • ML model assists in material selection and determining optimal restoration thickness over various clinical backgrounds. [ABSTRACT FROM AUTHOR]

Sliced veneer has the highest value as a facing material, provided that the natural color of the wood is preserved. Therefore, the study of the color characteristics of sliced veneer is of considerable practical importance. The object of the study is sliced veneer from European oak wood (Quercus robur L.), since it is produced in significant quantities by Ukrainian enterprises. The experimental studies were carried out under the production conditions of the Euroshpon LLC, which specializes in the production of sliced veneer. The color properties of sliced veneer were studied using the CIELab chromatic system. During the experimental studies, the duration of the steaming process was 16 hours at a steam temperature of 115°C, and the boiling process was 36 hours at a water temperature of 98°C. The sliced veneer samples were taken at a depth of 5 cm, 10 cm, 15 cm from the surface of the specimens for atmospheric drying and kept at a temperature of 20 °C and relative humidity near 50% during 14 days (for chamber drying at a temperature of 135 °C - within 120 s). In order to determine the natural color of oak wood, a reference sample of sliced veneer was taken, obtained from wainscots that had not undergone hydrothermal treatment. The sample was taken based on its uniform texture and color and obtained from logs that had not undergone hydrothermal treatment. Also, this sample was not subject to kiln drying. During the heat treatment (steaming, boiling), the temperature distribution across the cross section of the sample is not uniform. Wood at a depth of 50 mm warms up faster and to higher temperatures than at depths of 100 and 150 mm. According to the results of the experimental studies, the сolor scale readings of the reference sample are as follows: L*=65.80; a*=6.59; b*=23.39. The brightness of sliced oak veneer made from steamed wainscots and dried in the atmospheric conditions is L*=63.57-65.52, while the brightness of the sample dried in a drying chamber is L*=62.79-65.09. The brightness of sliced oak veneer made from boiled logs and dried in the atmospheric conditions is L*=63.82-65.43, the brightness of the sample dried in a drying chamber is L*=63.55-64.88. The parameter a* for sliced veneer sample taken from steamed wainscots is a*=5.03-5.58, and for sliced veneer sample taken from boiled wainscots is a*=6.24-6.97. The parameter a* for sliced veneer taken from steamed wainscots is a*=5.03-5.58, and for sliced veneer sample taken from steamed wainscots, the parameter a*=6.24-6.9 The component b* for sliced veneer sample taken from steamed wainscots is b*=20.21-20.85, and for sliced veneer sample taken from steamed wainscots – b*=20.47-20.99. The obtained research results can be applied in production conditions for the purpose of adjusting hydrothermal treatment modes and other processes in the manufacture of sliced oak veneer. The technological operation of oak logs boiling in the production of sliced veneer is recommended to be used in the case when it is necessary to achieve a lighter and more uniform color of the veneer, taking into account a longer process of heat treatment. Steaming oak logs has some advantages when it is necessary to increase manufacturing productivity without taking into account the color characteristics of the veneer.

This study investigated the potential of petal colorimetric data to classify vase life stages in cut lisianthus flowers (Eustoma grandiflorum). We analyzed the changes in the petal color space over time, focusing on the b* value as an indicator of senescence due to increasing yellowing caused by copigmentation. A comparative analysis was conducted between two cultivation methods: soil (S) and hydroponic (H) cultivation. The objective was to evaluate the performance of machine learning models trained to classify vase life stages based on petal color data. Automated machine learning models exhibited better performance in H-cultivated cut flowers, effectively distinguishing days within the vase life stages from Days 1 to 14 for H cultivation. Cut flowers cultivated under S conditions showed less variation in the color space from Days 1 to 9, maintaining a relatively uniform color range. This made it more difficult to distinguish the vase life stages compared to H cultivation. These findings demonstrate that petal color metrics can serve as reliable indicators of cut flower senescence and potentially facilitate nondestructive methods for classifying vase life stages. This technology holds promise for wider applications in the floriculture industry, improving quality control, and extending the vase life of various cut-flower crops.

This study aimed to evaluate the staining sensitivity and surface changes in recent composite resins (Herculite Ultra XRV (Kerr, Bolzano, Italy), G-ænial A’CHORD (GC Corp, Tokyo, Japan), and Omnichroma (Yamaguchi, Japan)) when exposed to common beverages such as coffee, red wine, and Coca-Cola. A total of 60 disk-shaped specimens were prepared from three different resin composites (n = 20 each). The specimens were exposed to coffee, red wine, and Coca-Cola for 10 days. Color measurements were taken using a spectrophotometer, and surface morphology and elemental composition were analyzed using SEM and EDS. The SEM and EDS analyses revealed significant changes in the surface morphology and elemental composition of the composites after immersion. Coffee and wine caused significant surface degradation, whereas Coca-Cola resulted in the greatest degree of surface and elemental variations. Color changes (ΔE = 4 ± 0.52) were most notable in Coca-Cola for Herculite Ultra XRV (Kerr, Italy), in red wine for G-ænial A’CHORD (GC Corp, Japan) (ΔE = 12.51 ± 0.38), and in coffee for Omnichroma (Yamaguchi, Japan) (ΔE = 10.85 ± 1.03). The tested beverages significantly affected both the surface condition and the chemical composition of the resin at the surface level. These findings highlight the importance of understanding the effects of common dietary beverages on dental composites.

Abstract Currently, most of the methods for mineral materials analysis generate secondary pollution, which is detrimental to human health. For instance, traditional methods for sphalerite analysis in the zinc (Zn) smelting industry including chemical titration, atomic absorption spectrometry, and inductively coupled atomic emission spectroscopy. Colored indicators and toxic heavy metals are used in the analytical processes, causing severe pollution. For some methods, liquid is transformed into gaseous plasma, which is more dangerous to human health. Due to large quantities of sphalerite being used, secondary pollution cannot be ignored. This study proposes a green analysis method for the detection of sphalerite based on colorimetry, which does not generate secondary pollution. The results show that the strong substitution ability of iron (Fe) for Zn contributes to their inverse correlation in contents. The lattice parameters decrease with the increasing Fe content, resulting in a darker coloration. Here, key colorimetry parameters of L*, a*, and b* show clear linear correlations with the Zn and Fe contents. Compared with traditional approaches, this new method is environmental friendly with high sensitivity and accuracy. The relative error and relative standard deviation were less than 10% and 5%, respectively. This study provides a significant reference for nonpollution determination of other mineral materials.

Societal Impact Statement In blueberry, fruit color is one of the most important quality traits affecting consumers' choices. Both pigments and waxes impact fruit color; however, their roles have not been clearly elucidated. Here, the contributions of waxes and anthocyanins to fruit color are characterized. A higher content of β‐diketones—the second largest wax group in blueberries—determines a lighter fruit color; hence revealing that, at harvest, waxes contribute more than anthocyanins in determining variations in fruit color among blueberry varieties. Summary Fruit color is one of the major quality traits determining the marketability of fruits by affecting consumers' choices. In blueberries, although fruit surface color is mainly determined by pigments (e.g., anthocyanins), cuticular waxes also play a role in modulating the surface color, and a lighter color given by a dense wax bloom is normally preferred by consumers. This study investigated the content and composition of cuticular waxes and their roles in modulating fruit surface color in 12 (seven northern highbush, three southern highbush, and two hybrids) blueberry genotypes at harvest (H1, representing the first commercial pick, and H2, representing the second commercial pick). The ultrastructural morphology of cuticular waxes was analyzed in four selected genotypes by scanning electron microscopy. The level and profile of anthocyanins and their contributions to the color were also assessed. Total cuticular wax content ranged from 27.7 to 95.8 μg cm−2 among genotypes at H1 and decreased by an average of 23.9% from H1 to H2. Triterpenoids (62.5% of the total cuticular waxes on average) and β‐diketones (22.9% on average) were the first and second largest wax groups in all genotypes, respectively. β‐Diketones were previously proven to affect leaf surface color in wheat; in this study, their content strongly correlated with the lightness of the blueberry surface. Scanning electron microscopy revealed distinct wax morphologies among genotypes. No significant relationships were found between total or individual anthocyanin concentrations and fruit surface color. Our results suggest that, at harvest, variation in the fruit surface color among blueberry genotypes is more closely related to the content and composition of cuticular waxes than the level and profile of anthocyanins, with β‐diketones being particularly important. This study provides new insights for blueberry breeding programs aiming to improve the surface color in order to meet the market demand.

The purpose of this study was to investigate the contribution of Caesalpinia sappan (sappan wood) bark extractives by analyzing color change of the bark after extraction and the color of the extracts with several color measurement methods. Successive extraction was performed with n-hexane, ethyl acetate, methanol, and hot water. Color change of the bark was measured using CIELab color system and the extracts were analyzed with Ultraviolet-Visible Spectrophotometer, total phenolic content (TPC), and Gas Chromatography Mass Spectrometry (GC-MS). The results showed that the highest change on the bark color after methanol extraction with the Δa* and Δb* values of -2,53 ± 0,60 and -3,64 ± 1,20 respectively. Also, methanol extract showed the highest total phenolic content (860,24 ± 30,19 mg GAE/g). In addition, the Ultraviolet-Visible is analysis showed a peak at 478 nm in the hot-water soluble extract and two peaks in the methanol soluble extract at 396 nm and 478 nm. Hydroquinone was detected as one of the major compounds by Gas Chromatography Mass Spectrometry in the methanol soluble extract. It was suggested that the color of Caesalpinia sappan (sappan wood) bark as well as the deep red coloration of its extract might be contributed by multiple phenolic compounds contained in the methanol extract with hydroquinone as its precursor. Therefore, it is also a potential source for coloring matter.

Purpose: To determine the effect of potassium iodide (KI) on the black/gray staining caused by silver diammine fluoride (SDF) when applied to carious lesions. Methods: Extracted caries-free molar surfaces had caries induced to examine the use of SDF and SDF followed by KI (SDF+KI) on extracted permanent molars that had caries induced on their surfaces and were monitored for a period after application. To monitor the color changes, CIELAB color space readings-a color space defined by the International Commission on Illumination-were used. The system is composed of three values, of which the L* measures black to white across a span of zero (black) to 100 (white). Measurements were taken at eight intervals between days zero to 72. Results: L* values were found to be significantly different between SDF and SDF+KI groups and from baseline. On average, the SDF+KI group versus the SDF group was 9.47 units lighter. Conclusion: The findings indicate the application of silver diammine fluoride followed by potassium iodide can reduce the black staining SDF alone causes, potentially making it a viable esthetic option for patients with anterior tooth caries. [ABSTRACT FROM AUTHOR]

Pea protein is a plant-based fining agent recently approved for the clarification of musts and wines. Vegetal proteins are intended to replace the classical fining agents based on proteins of animal origin or the synthetic polymer polyvinylpolypyrrolidone (PVPP), which both proved very efficient for partial removal of polyphenols, but are less accepted by vegetarian or eco-friendly consumers. As an alternative, pea protein can be used for clarification either alone or in complex products containing other non-animal materials. This paper focuses on the evaluation of several pea protein based fining agents used to clarify the must of Tămâioasa românească, an aromatic grape variety which is vinified with a short maceration, leading to wines with a higher content of polyphenols. Variants with no fining as well as PVPP fining were also produced. For all fining variants, the clarification was performed both with oxygen protection and in the presence of oxygen. UV-visible spectroscopy was used to determine parameters related to the content of phenols in the resulted wines (total phenol index as OD 280 nm, flavonoids as OD 365 nm, CIELab parameters and colour differences), after must clarification and completion of the fermentation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the contribution of Caesalpinia sappan (sappan wood) bark extractives by analyzing color change of the bark after extraction and the color of the extracts with several color measurement methods. Successive extraction was performed with n-hexane, ethyl acetate, methanol, and hot water. Color change of the bark was measured using CIELab color system and the extracts were analyzed with Ultraviolet-Visible Spectrophotometer, total phenolic content (TPC), and Gas Chromatography Mass Spectrometry (GC-MS). The results showed that the highest change on the bark color after methanol extraction with the Δa* and Δb* values of -2,53 ± 0,60 and -3,64 ± 1,20 respectively. Also, methanol extract showed the highest total phenolic content (860,24 ± 30,19 mg GAE/g). In addition, the Ultraviolet-Visible is analysis showed a peak at 478 nm in the hot-water soluble extract and two peaks in the methanol soluble extract at 396 nm and 478 nm. Hydroquinone was detected as one of the major compounds by Gas Chromatography Mass Spectrometry in the methanol soluble extract. It was suggested that the color of Caesalpinia sappan (sappan wood) bark as well as the deep red coloration of its extract might be contributed by multiple phenolic compounds contained in the methanol extract with hydroquinone as its precursor. Therefore, it is also a potential source for coloring matter. [ABSTRACT FROM AUTHOR]

Although the effect of thermal modification (TM) on teak wood color is well documented, few studies have been carried out on closed-system processes, and it remains unclear what the effect is of different processes on the same material. This work aimed to verify the effect of closed- and open-system processes of TM on the color of short-rotation teak wood. Thermally modified wood (TMW) was evaluated in a closed system at 160 °C (CS160) and in an open system at 185 °C and 210 °C (OS185 and OS210). We measured the moisture content (initial and final) of the wood and the corrected mass loss (CML). The chemical analyses encompassed the contents of alpha-cellulose, hemicelluloses, lignin, and extractives (total, in acetone and dichloromethane). Wood color was measured before and after TM according to the CIEL*a*b* color space. It was possible to achieve the same color using different processes of thermal modification (CS160 and OS210). TM reduced wood lightness (L*), red–green chromaticity coordinate (a*), and yellow–blue chromaticity coordinate (b*). L* and a* had the biggest and smallest variations, respectively. TMW color was significantly changed, even at the mildest condition tested (OS185, 0.33% CML). [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to observe and evaluate the long- and shortterm discoloration tendencies of lithium disilicate-based glass-ceramics (IPS e.max CAD LT) and leucite-based feldspathic glass-ceramics (VITA Mark II) materials, which are esthetically very close to each other at first glance. Methodology: 80 pieces of lithium disilicate and feldspathic blocks (A2 colored) were overglazed and polished separately to evaluate the surface treatment procedures according to CIELAB color coordinates. For accelerated aging purposes, half of the samples were treated with red wine, and the other half were treated with coffee. Color changes were calculated using the ΔE formula. The results were represented as ΔE-1, ΔE-2, and ΔE-3. Data distribution regarding numerical variety and changes was evaluated using the Shapiro-Wilk normality test and Q-Q graphics. Results: The data was evaluated using O'Brien clinical color tolerance scales. After 4 weeks of accelerated aging, any of the samples did not show a perfect (ΔE=0-0.5) color match. Both groups have shown significant statistical changes at various rates and percentages. Conclusion: Since aging procedures affect ceramic systems' ΔE values in a variety of ways, the aging protocol utilizing in vitro aging techniques for color change should be evaluated alongside ceramic type and surface finishing procedures. [ABSTRACT FROM AUTHOR]

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Three new approximately uniform color spaces named MLUV, MLUV1, and MLUV2 were developed by modifying CIELUV lightness, u′v′ chromaticity coordinates, and u*v* color coordinates, respectively. Performance tests using the combined and four individual datasets employed at CIEDE2000 development showed that MLUV, MLUV1 and MLUV2 were significantly better than CIELUV. Using values of Standardized Residual Sum of Squares (CIE 217:2016) for predictions of the four individual datasets the ranking (from best to worst) was MLUV, MLUV2 and MLUV1, but for predictions of two ellipses datasets the ranking (from best to worst) was MLUV2, MLUV, and MLUV1. Overall, the MLUV2 space was found to be the best. Hence, it is expected that MLUV2 could be used for color specification and color difference evaluations, especially in industrial applications that depend on additive light mixing, such as color TV sets, video monitors, and lighting. [ABSTRACT FROM AUTHOR]

In this study, seventeen faceted gem-quality chrysoberyls exhibiting an attractive canary yellow color were investigated using a variety of gemological, spectral, and chemical methods. Microscopic observation revealed the presence of distinct growth lines and inclusions, including CO2 fluids, carbon, and crystals of mineral such as calcite, quartz, sillimanite, and mica, identified by the Raman spectrum. The FTIR spectra showed the characteristic peaks of 2405 and 2160 cm−1 and a 3223 cm−1 peak in all samples, which can be accompanied by the 3112 cm−1 shoulder, 3301, and 3412 and 3432 cm−1 peaks. The UV-Vis spectra showed an Fe-related peak at 440 nm, along with the 650–660 nm band and the absorption band in the blue zone of visible light. Chemical analyses via EDXRF showed a composition poor in V and Cr and rich in Fe. The spectral and chemical results could help explain the origin of the canary yellow color, which originates from the abundant amount of Fe with very little influence from Cr and V. [ABSTRACT FROM AUTHOR]