Spectral Color Research Articles

Target Analyte Interaction with a New Julolidine Coupled Benzoxazole‐based Dyad: A combined Photophysical, Theoretical (DFT), and Bioimaging Study

AbstractA julolidine‐coupled benzoxazole‐based fluorescent chemosensor (BPOZ) is designed and developed to investigate the different target analyte interactions spectroscopically. Based on the ′off‐on‐off′ photoluminescence mechanism, the as‐prepared BPOZ is used for sequentially detecting Zn2+ and HSO4− ions, respectively. The UV‐visible absorption and photoluminescence spectral behavior is intramolecular charge transfer (ICT) in nature. When Zn2+ ions bind with BPOZ, its fluorescence is significantly enhanced at 512 nm due to chelation‐enhanced fluorescence. A green color emission is also visible under 365 nm UV light exposure, which is also confirmed by the color chromaticity diagram. Chelation‐enhanced photoluminescence is also manifested in the lifetime decay analysis. Further, it is well supported by different spectroscopic techniques and DFT analysis. In the presence of HSO4− ions, photoluminescence of the Zn2+ chelated BPOZ complex is significantly reduced, rebirthing the free BPOZ. The detection limit of BPOZ for Zn2+ and Zn2+ chelated BPOZ complex towards detecting Zn2+ and HSO4− ions is established to be in the order of nM and μM range, respectively, in the solution phase. Among the various explosive nitroaromatic compounds, picric acid (PA) quenched the emission of the Zn2+ chelated BPOZ complex, and the quenching mechanism is found to be both static and dynamic in nature. Using these chemically prearranged inputs and optical outputs, two inputs, INHIBIT, and three inputs, combinational logic gates have been constructed. The BPOZ chemosensor and Zn2+ chelated BPOZ complex are also employed to map Zn2+ ions and PA in the living cell. The performance of the BPOZ chemosensor and Zn2+ chelated BPOZ complex toward Zn2+ ions and PA proved that it could be exploited as a signal tool for environmental and biological samples.

Predictability and outcome of titanium color after different surface modifications and anodic oxidation.

To investigate the predictability and the outcome of surface modification techniques, including anodization. Four surface modification techniques were evaluated in this in-vitro study: sandblasting (S), polishing+anodizing (PA), sandblasting+anodizing (SA), polishing+etching+ anodizing (PEA). Color coordinates L*, a* and b* were collected using a spectroradiometer. Color differences between all groups were quantified by use of ΔE00. A possible influence of group membership was evaluated using 1-way ANOVA. Pair-wise inter-group comparisons were performed using post-hoc Tukey tests. PA specimens were the brightest and showed a pronounced yellowish and reddish hue. S and SA groups were significantly darker and predictability of outcome was higher compared to another groups. The most predictable surface treatment method is sandblasting. Anodizing techniques come along with the brightest and most chromatic color impression of the titanium.

A Coumarin151 derived ratiomteric and turn on chemosensor for rapid detection of sarin surrogate

A coumarin151-derived electron donor–acceptor-based dyad (DATC) has been designed and developed for the selective detection of sarin surrogate diethylchlorophosphate (DCP) in solution and gas phases, respectively. A ratiometric UV–visible absorption spectral change with a colorimetric visualization from yellow to colorless is observed in the presence of DCP. Turn-on fluorescence at 480 nm is found due to the disrupted excited state intramolecular proton transfer process (ESIPT) within the DATC. Also, the photoinduced electron transfer (PET) process from electron-rich N, N-diethylamino (-NEt2), and imine (–CH = N) functional groups to coumarin moiety is inhibited due to the phosphorylation process. A visual cyan color could be seen under 365 nm UV light irradiation, which is also well supported by the color chromaticity diagram. The sensitivity of DATC toward the detection of DCP can be possible down to the nanomolar (nM) range from aqueous to a non-aqueous medium. Further, a paper strips-based test kit has been fabricated for the practical utility of the present DATC probe to identify a trace amount of DCP in the stockpiles of related analytes. Also, a dip-stick experiment has been demonstrated for the selective detection of DCP vapor. The performance of DATC toward the DCP proved that it could be exploited as a signal tool for real sample analysis.

The effect of different mordants on natural dyeing of cotton, viscose and lyocell fabrics with pomegranate bark extracts

Considering the growing environmental awareness, natural dyeing is considered as a sustainable approach in textile dyeing, which can minimize the environmental impacts of synthetic dyes. In this study, it was aimed to compare the dyeing properties of different cellulose-based fabrics (100% cotton, 100 % viscose, 100% Tencel) with pomegranate bark extract as a natural dye by using two different mordants (potassium aluminium sulfate and iron (II) sulfate). Results revealed that potassium aluminium sulfate (alum) and iron (II) sulfate gave different color shades from light to medium yellowish-brown shades with different color depth (K/S) and color vividness (chroma). Alum mordant resulted in lighter, more greenish and more yellowish shades with more vivid color than iron (II) sulfate. The maximum K/S of 3.5 was achieved with viscose fabric mordanted with iron (II) sulfate. All dyed samples had satisfied color fastness values and increased tensile and tear strength compared to raw fabrics.

The spectral color of natural and anthropogenic time series and its impact on the statistical significance of cross correlation

The cross-correlation between time series is a common tool to study and quantify the impact of climatic and anthropogenic changes on ecosystems. The traditional method for estimating the statistical significance of correlation relies on the assumption that the data are independent, but time series found in nature are often strongly auto-correlated because of low-frequency environmental variability and ecosystem inertia. Previous authors have used Monte Carlo simulations to study the impact of serial auto-correlation on the significance of cross-correlations. Most studies have used random time series that are often a poor representation of those found in nature, e.g., low-order auto-regressive models with normally distributed noise. Moreover, we are not aware of any tests of the applicability of those methods to anthropogenic time series. Here, we study the effect of serial auto-correlation on the performance of two methods for estimating the significance of cross-correlations determined from Monte Carlo simulations with time series that are generated synthetically based on power-law specification of spectral characteristics. Such time series have an auto-correlation structure defined by a single parameter, their spectral “color”, and are generally more convenient representations of natural time series than the autoregressive models. Our results show that one of the two methods considered here accurately reproduces prescribed error rates for the wide range of spectral colors representative of climatic, ecological and anthropogenic time series. For this, we characterized roughly 1800 observational records in different categories of spectral colors, including climate variability, abundance of vertebrate species, and pollution. We specifically focus on time series with annual sampling over data records of at least 40 years, which are particularly relevant for climate studies. The methodology advocated in this study provides a simple and realistic assessment of the significance of sample estimates of cross correlation for time series with any sample interval and record length.

Influence of Ambient Temperature on Optical Characteristics and Power Consumption of LED Lamp for Automotive Headlamp

In this study, the authors propose a method for evaluating the influence of ambient temperature (Ta) on the optical characteristics and power consumption of a LED lamp used for the automotive headlamp, which helps the designer to figure out the acceptable range of the ambient temperature for the LED lamps to work well in the practical case. The LED lamp was fixed on the test holder and placed in a fixed position in the air circulation temperature control oven to measure the illuminance, spectrum in three different directions, and power consumption under various Ta. The experimental results indicate that Ta has little effect on the correlated color temperature (CCT), chromaticity coordinates, and angular distribution of the emitting light. In contrast, Ta has a significant effect on the lamp’s resistance, thus affecting illuminance and power consumption. When the Ta increased from 30 °C to 60 °C, the illuminance of the low beam and high beam decreased on average by 16.6% and 21.7%, respectively, while the power consumption of the low beam and high beam decreased on average by 21.4% and 22.2%, respectively. The drop in the luminous flux output indicates the probability of originally qualified automotive LED headlamps becoming unqualified in high Ta.

Colors and Learner’s Gender Evoke Different Emotional and Cognitive Effects in Multimedia Learning

The emotional design principle avers that highly saturated warm colors in multimedia learning presentations can elevate affective-motivational, cognitive, and learning outcomes. While warm and achromatic grayscale color tones have been explored extensively, relatively less research examines the effects of cold colors in multimedia learning. This study explores how color tones (warm, cold, and achromatic grayscale) and learners’ gender influence positive emotions, intrinsic motivation, cognitive load, and transfer performance. An online experiment was conducted where learners pursuing IT courses in an Asian university (n=204) engaged with either one of the multimedia learning lessons on distributed denial-of-service attack imbued with (1) a warm color tone, (2) a cold color tone, and (3) an achromatic grayscale color tone. Findings show that the cold color tone was associated with fewer enhanced positive emotion types than the other color tones. Compared to the achromatic grayscale color tone (M=2.38,SD=1.88), significantly higher extraneous cognitive load ratings were observed with the warm color tone (M=3.26,SD=1.96) and the cold color tone (M=3.24,SD=2.18). Following reports by some learners, this could be attributed to the overly vivid and saturated chromatic colors impairing the learners’ visual and cognitive processes, causing them to rate the multimedia learning experience with warm and cold color tones as more difficult than with the achromatic grayscale color tone. Male learners in the warm color tone condition (M=4.93,SD=3.46) performed marginally better on the transfer posttest than male learners in the cold color tone condition (M=3.49,SD=3.45) and male learners in the achromatic grayscale color tone condition (M=3.44,SD=2.69). In contrast, female learners in the warm color tone condition (M=1.75,SD=1.62) performed marginally worse than female learners in the cold color tone condition (M=3.83,SD=3.92) and significantly worse than female learners in the achromatic grayscale color tone condition (M=3.67,SD=2.50). Overall, these results show that gender can shape the effects of warm colors on learning—the warm color tone can enhance male learners’ but stifle female learners’ transfer performance. Moreover, this study aligns with recent studies that colors as an emotional design feature may lead to higher cognitive load ratings. This paper discusses the theoretical and practical implications and submits a future outlook for broadening the research domain.

A Survey on the Color of Bedroom Space in the Youth Generation According to Independence

Among the residential spaces, the bedroom space is the space where the young generation spends the longest time, so care should be taken in color planning so that they can spend a more satisfying time. In addition, the color environment is also different because there is a difference in the shape of the space used by the young generation and the degree of consideration when choosing the color of the bedroom space depending on the independence. Therefore, this study conducted a survey of 201 young people from March to September 2021 consisting of general matters, color preferences, matters for understanding the actual situation, and matters regarding current colors and desired colors. As a result, the younger generation preferred achromatic colors, especially white, more than chromatic colors in the bedroom space, and hoped that the most preferred color would be used depending on whether they were independent or not. The youth generation is expected to be a helpful resource for color planning that meets individual preferences as their housing types are diverse as their circumstances are diverse, such as college students and newlyweds.

Effect of dye bath pH in dyeing of cotton knitted fabric with reactive dye (Remazol Yellow RR) in exhaust method: impact on color strength, chromatic values and fastness properties

The significance of textile coloration is inevitable as coloration is a critical process and it can be affected by several parameters i. e. time, temperature, pH, and liquor ratio (M:L). This research reveals the behavior of different dye bath pH (2 to 12) on the basis of spectrophotometric characteristics and colorfastness using the most useable brand of reactive dye in Bangladesh i. e. Remazol Yellow RR. Earlier researches were performed on the basis of other coloration controlling factors i. e. temperature, time and liquor ratio (M:L) where pH acts as the dependent variable. However in this study, pH was taken as an independent variable where lower pH (2, 4 and 6), medium pH (8 and 10) and higher pH (12) were taken into consideration for verifying the dyeing performance. Meanwhile, the mentioned pH was achieved by adding acetic acid, soda ash and caustic soda respectively. In this study, the impact of pH is analyzed on the basis of color strength, chromaticity, hue angle, CIELAB color space, spectrophotometric image, reflectance percentage and color fastness tests i. e color fastness to rubbing, color fastness to wash, color fastness to perspiration, color fastness to light. Gradually elevated pH boosts up the color strength and chromaticity, at the same time downgrades of hue angle results orangish tone in the dyed fabric. Even more, the lightness of dyed fabric decreases and redness rises with the increment of dyebath pH which results in orangish red darker tone of dyed fabric. Consequently, fabric dyed at acidic dye bath pH exhibits higher resistance in case of color change and color staining from the dyed fabric and multifiber fabric respectively and vice versa.

Study on Spectral Characteristics and Color Origin of Scheelite from Xuebaoding, Pingwu County, Sichuan Province, P.R. China

The Xuebaoding deposit, which is located 14.5 km northwest of Huya Town, Pingwu County, Mianyang City, Sichuan Province, China, produces a kind of yellow-orange-hued scheelite with ideal crystal shapes, large-grain crystals, and high market value which is favored by gem and mineral crystal collectors. In this article, five Xuebaoding scheelite samples are used as research objects. The infrared absorption in the fingerprint region (2000 to 400 cm−1) of scheelite is at 440 cm−1 and 800 to 900 cm−1, which shows the out-of-plane bending vibration and asymmetric stretching vibration attributed to the [WO4]2− tetrahedral group, respectively. The Raman shift at 911 cm−1 is assigned to the ν1 symmetric stretching vibration of [WO4]2−; the Raman spectra scattering peak at 797 cm−1 belongs to the ν3 asymmetric stretching vibration of [WO4]2−; the Raman shift at 332 cm−1 and the low-intensity Raman scattering peak near 400 cm−1 belong to the ν2 out-of-plane bending vibration of [WO4]2−. Furthermore, the low-intensity Raman shift around 211 cm−1 is caused by the transitional mode of (Ca–O). The UV-Vis-NIR absorption is attributed to the existence of “didymium”, a mixture of the rare earth elements Pr and Nd, and the absorption at 584 and 803 nm is assigned to Nd, which may be related to origin of the color of scheelite. The 3D fluorescence spectra show that the colorless and colored scheelite samples produce the same number of main fluorescence peaks with similar positions. Those 3D fluorescence peaks are located near λex235 nm/λem455 nm, λex250 nm/λem490 nm, and λex265 nm/λem523 nm. In addition to the above-mentioned main fluorescence peaks, the pale-yellow-colored samples also produced fluorescence peaks near λex250 nm/λem425 nm, which may be associated with the rare earth elements in scheelite. Combined with the test results of LA-ICP-MS, the yellow-orange hue of Xuebaoding scheelite is caused by the isomorphic rare earth elements, such as La, Ce, Pr and Nd ions that replace Ca2+.

Comparative psychophysics of Western honey bee (Apis mellifera) and stingless bee (Tetragonula carbonaria) colour purity and intensity perception.

Bees play a vital role as pollinators worldwide and have influenced how flower colour signals have evolved. The Western honey bee, Apis mellifera (Apini), and the Buff-tailed bumble bee, Bombus terrestris (Bombini) are well-studied model species with regard to their sensory physiology and pollination capacity, although currently far less is known about stingless bees (Meliponini) that are common in pantropical regions. We conducted comparative experiments with two highly eusocial bee species, the Western honey bee, A. mellifera, and the Australian stingless bee, Tetragonula carbonaria, to understand their colour preferences considering fine-scaled stimuli specifically designed for testing bee colour vision. We employed stimuli made of pigment powders to allow manipulation of single colour parameters including spectral purity (saturation) or colour intensity (brightness) of a blue colour (hue) for which both species have previously shown innate preferences. Both A. mellifera and T. carbonaria demonstrated a significant preference for spectrally purer colour stimuli, although this preference is more pronounced in honey bees than in stingless bees. When all other colour cues were tightly controlled, honey bees receiving absolute conditioning demonstrated a capacity to learn a high-intensity stimulus significant from chance expectation demonstrating some capacity of plasticity for this dimension of colour perception. However, honey bees failed to learn low-intensity stimuli, and T. carbonaria was insensitive to stimulus intensity as a cue. These comparative findings suggest that there may be some common roots underpinning colour perception in bee pollinators and how they interact with flowers, although species-specific differences do exist.

Effect of hazelnut skin by-product supplementation in lambs' diets: Implications on plasma and muscle proteomes and first insights on the underlying mechanisms

This study aimed to evaluate the effect of hazelnut skin by-product supplementation on lamb meat quality characteristics and plasma and muscle proteomes. Twenty-two Valle del Belice male lambs were divided into two experimental groups: control (C), fed a maize-barley diet and hazelnut (H), fed hazelnut skin by-product as maize partial replacer in the concentrate diet. The meat of lambs fed hazelnut skin showed greater values of lightness, redness, yellowness, and chroma color parameters together with the highest myofibril fragmentation index. Two-dimensional electrophoresis and mass spectrometry applied on plasma proteome identified 20 protein spots corresponding to 18 unique gene names to be differently expressed due to hazelnut skin by-product substitution. For the early post-mortem muscle, 23 protein spots (42 unique gene names) were significantly up-regulated due to hazelnut skin by-product supplementation. Four proteins these being APOA1, PHB, ACTG1 and ALB, were found to be common to the two proteomes suggesting that these proteins could be candidate biomarkers to monitor in vita and post-mortem lamb meat quality traits. This study evidenced the main mechanisms involved in the supplementation of hazelnut skin by-product in lambs' diet and confirmed the possibility of using plasma proteome as a non-invasive way to predict lamb meat quality. SignificanceMaximizing the use of agro-industrial by-products as replacers of traditional feedstuff for improving animal products is one of the important challenges to preserving natural resources and guaranteeing environmental sustainability. Hazelnut (Corylus avellana L.) skin, obtained as a results of hazelnut roasting, represents a valuable by-products due to its high content in unsaturated fatty acids, tannins, and vitamins. Thus, including hazelnut skin by-product in small ruminant nutrition could reduce the costs of animal feedings for farmers as well as improve meat nutritional and sensorial characteristics. Additionally, monitoring the meat quality characteristics with fast, accurate, and non-invasive tools to find, before slaughter, animals with desired quality characteristics is of growing interest in the last years. In this regard, the objectives of this study were to assess i) the effect of hazelnut skin supplementation on lamb meat quality characteristics and plasma and muscle proteomes, and ii) whether analyzing plasma proteome by using a gel-based proteomic approach could effectively offer a more readily available option for determining lamb meat quality. Taken together, the proteomic approach applied to plasma and muscle proteomes, allowed us to reveal the pathways and the potential candidate plasma biomarkers to predict lamb meat production in the pre-slaughter phase.

Acidic electrolyzed water treatment suppresses Phomopsis longanae Chi-induced the decreased storability and quality properties of fresh longans through modulating energy metabolism

Longan fruit loses its market value rapidly due to postharvest pathogenic infestation and quality deterioration. Here, we hypothesized that acidic electrolyzed water (AEW) could maintain higher quality of P. longanae-inoculated longans via regulating energy metabolism. Results indicated that AEW reduced fruit disease index and decay incidence. Significantly, AEW treatment retained higher levels of ATP, ADP, and energy charge, and higher activities of Ca2+-ATPase, Mg2+-ATPase, and H+-ATPase in the membranes of plasma, vacuole, and mitochondria, which maintained the structural and functional integrity of cell membrane. Furthermore, indirectly sustaining cell membrane function via AEW treatment could maintain the storability and quality properties of longans, including keeping higher values of color chromaticity (L*, a*, and b*), higher amounts of vitamin C, total soluble solids, sucrose, and total soluble sugars, lower titratable acid and reducing sugar contents. This work elucidated the potential regulation of AEW on the balance of energy metabolism and fruit quality.

A multimodal molecular image fusion method based on relative total variation and co‐saliency detection

Image fusion can integrate complementary information from multimodal molecular images to provide an informative single result image. In order to obtain a better fusion effect, this article proposes a novel method based on relative total variation and co-saliency detection (RTVCSD). First, only the gray-scale anatomical image is decomposed into a base layer and a texture layer according to the relative total variation; then, the three-channel color functional image is transformed into the luminance and chroma (YUV) color space, and the luminance component Y is directly fused with the base layer of the anatomical image by comparing the co-saliency information; next, the fused base layer is linearly combined with the texture layer, and the obtained fused result is combined with the chroma information U and V of the functional image. Finally, the fused image is obtained by transforming back to the red–green–blue color space. The dataset consists of magnetic resonance imaging (MRI)/positron emission tomography images, MRI/single photon emission computed tomography (SPECT) images, computed tomography/SPECT images, and green fluorescent protein/phase contrast images, each category with 20 image pairs. Experimental results demonstrate that the proposed method RTVCSD outperforms the nine comparison algorithms in terms of visual effects and objective evaluation. RTVCSD well preserves the texture information of the anatomical image and the metabolism or protein distribution information of the functional image.

Analysis of thermal chromaticity stability, energy transfer and colour tunablity of Dy3+-Eu3+ doped BBZL glasses for high-power W-LED applications

A family of highly thermal chromatic stable Dy3+-Eu3+ doped B2O3-Bi2O3-ZnO-Li2O (BBZL) glass samples was synthesised using the high-temperature melt quenching technique. The optical and thermal stability properties of the samples were analysed using their fluorescence spectra at various temperatures, fluorescence lifetime decay times and colour coordinates. The Dy3+-doped BBZL (BBZL: Dy) glass samples generated cold white light when exposed to ultraviolet (UV) light, while the Dy3+-Eu3+-doped BBZL (BBZL: DyEu) glass samples emitted neutral and warm white light, which can be attributed to the introduction of Eu3+ that substantially enhanced the colour rendering of samples. An overlap of the excitation-emission spectra of Eu3+ and Dy3+ indicated an energy transfer between Dy3+ and Eu3+. Under a 350 nm excitation, the fluorescence lifetime of BBZL: DyEu decreased from 0.5348 to 0.3642 ms. Using the Dexter theory, the energy transfer between Dy3+ and Eu3+ was demonstrated to be an electric dipole-electric dipole leap. The chromaticity shifts of BBZL: DyEu were 8.60 × 10−4 and 9.40 × 10−4 at 448 and 498 K, respectively, reflecting the high thermal stability of the sample chromaticity. The study demonstrated that Dy3+-Eu3+ doped borate glasses can be used as tunable luminescent materials in high-power white light-emitting diodes to mitigate the chromaticity shift in fluorescent materials at high temperatures.

A spectral three-dimensional color space model of tree crown health.

Protecting the future of forests in the United States and other countries depends in part on our ability to monitor and map forest health conditions in a timely fashion to facilitate management of emerging threats and disturbances over a multitude of spatial scales. Remote sensing data and technologies have contributed to our ability to meet these needs, but existing methods relying on supervised classification are often limited to specific areas by the availability of imagery or training data, as well as model transferability. Scaling up and operationalizing these methods for general broadscale monitoring and mapping may be promoted by using simple models that are easily trained and projected across space and time with widely available imagery. Here, we describe a new model that classifies high resolution (~1 m2) 3-band red, green, blue (RGB) imagery from a single point in time into one of four color classes corresponding to tree crown condition or health: green healthy crowns, red damaged or dying crowns, gray damaged or dead crowns, and shadowed crowns where the condition status is unknown. These Tree Crown Health (TCH) models trained on data from the United States (US) Department of Agriculture, National Agriculture Imagery Program (NAIP), for all 48 States in the contiguous US and spanning years 2012 to 2019, exhibited high measures of model performance and transferability when evaluated using randomly withheld testing data (n = 122 NAIP state x year combinations; median overall accuracy 0.89–0.90; median Kappa 0.85–0.86). We present examples of how TCH models can detect and map individual tree mortality resulting from a variety of nationally significant native and invasive forest insects and diseases in the US. We conclude with discussion of opportunities and challenges for extending and implementing TCH models in support of broadscale monitoring and mapping of forest health.

Colour vision: From sensation to science (in Norwegian)

Throughout history there have been different approaches to pursuing a better understanding of colour and colour vision, depending on the phenomena one wanted to explain. For instance, although seemingly irreconcilable, the opponent-colour theory of Hering (with its yellow-blue and red-green chromatic pairs) and the three-colour theory of Young-Helmholtz (with red, green, and violet as mixture primaries) did in fact illuminate different aspects of colour vision. Thomas Young and Hermann von Helmholtz set out to explain the qualities of colours, but with the help of James C. Maxwell this theory eventually became a three-receptor theory describing additive colour mixtures and colour matches. The three-receptor theory is the foundation of trichromatic colour measurements and a thriving colour technology. Ewald Hering, who also had colour perception as his main concern, appears to have recognized the distinction between receptor excitations and perception. He postulated opponent physiological processes as basis for the two pairs of chromatic colours. Today these theories are combined in an attempt to understand how colour is processed in the higher brain centres.

P‐5.12: One‐way Observable Window Signage with Vivid Colors Using Dye‐doped and Scattering Layers Which Enable to Make Images Invisible from Back Side

It stands to reason that someone observes mirrored imaging according to the direction of viewing if you draw something on the transparent material. The authors dislike this mirrored imaging problem, although it is not a fatal defect. In 2021, our research group proposed window signage using dye‐doped thin film layer to avoid this problem of mirrored imaging. But our 2021 model had a defect that color vividness was less than colors painted on non‐transparent materials because the images of our window signage are painted or printed on the transparent material for one‐way observable signage. To solve this weak point, we needed to find new technology for generating color using a transparent material. This paper shows a one‐way observable window signage using dye‐doped and special light scattering thin layers for unidirectional color generating by light controls, how to make colors more vivid and material development.

Structural and photoluminescence properties of europium oxide doped fluoroborate optical glasses

A sequence of zinc-magnesium-lithium-fluoroborate (ZMLB) optical glasses doped with different Eu3+ concentrations were synthesized through melt quenching technique. The non-crystalline characteristic of the synthesized glasses was proved by X-ray diffraction studies and the FT-IR transmittance spectra have been used to study the various vibrational bands in glass systems. The photoluminescence characteristics were studied under an excitation with 393 nm and it exhibits four emission peaks around at 590, 615, 654 and 700 nm assigned to 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 electronic transitions of Eu3+ ion, respectively. Color chromaticity values were estimated from luminescence spectra for all the synthesized samples and these parameters indicate the emission in red color region and cold light emission. All these results suggest that the Eu3+ ions doped ZMLB glasses are a potential candidate for red light generation at 615 nm to explore the new material for solid state light emitting diode applications.

Maxwell's color box: Retracing the path of color matching experiments

In his 1860 paper On the theory of compound colours, James Clerk Maxwell described an instrument used to obtain a direct comparison between daylight and a mixture of three selected spectral colors. This investigation was part of Maxwell's study of human color vision, color perception, and color representation, and it encompasses his main achievements in the field. The working principle underlying this device provided the basis from which color diagrams have been derived, beginning with the standard chromaticity diagram proposed by the International Commission on Illumination in 1931. We describe a reconstruction of Maxwell's original version of the color box. Constructing and analyzing data obtained with such a replica could serve as a semester project for advanced optics students.