Visible Color Spectrum Research Articles

Method and analysis of color changes of facial skin after applying skin makeup

This study investigated facial skin color differences before and after makeup. Toward this goal, a photo gauge, devised with a pair of color checkers as a reference, collected face images. In addition, color calibration and a deep-learning method extracted the color values of representative areas of facial skin. The photo gauge photographed 516 Chinese females before and after applying makeup. Then, the collected images were calibrated by referencing skin color patches, and the lower cheek regions’ pixel colors were extracted using open-source computer vision libraries. Following the visible color spectrum of humans, the color values were computed in L*, a*, and b* of CIE1976L*a*b*. The results showed that the facial colors of the Chinese females changed to become brighter, less reddish, and less yellowish after applying the makeup, resulting in a paler skin tone. During the experiment, subjects were given five varieties of liquid foundation to choose one sample that best fits their skin. However, we failed to find any noticeable relationship between the individual’s facial skin color characteristics and the liquid foundation selected. In addition, 55 subjects were identified according to their makeup use frequency and skill, but their color changes did not differ from the other subjects. This study provided quantitative evidence of makeup trends in the Shanghai region in China, and the method proposes a novel approach toward remote skin color research.

Room-temperature Continuous-Wave Upconversion White Microlaser Using a Rare-earth-Doped Microcavity

White laser covering the visible color spectrum is critical in various applications including vivid display, holographic imaging, and light-based version of Wi-Fi, but it is still challenging to realize a white microlaser due to the rigorous requirement for the balance between the optical gain and feedback in a wide wavelength range. Here, we employ thulium, erbium, and ytterbium elements corporately for the upconversion white lasing by an individual ultrahigh-quality (Q) (up to 108) doped microcavity with microwatt thresholds for the red, green, and blue lasers. To the best of our knowledge, it is the first rare-earth-element-based room-temperature continuous-wave white microlaser. This microlaser also exhibits relatively stable chromaticity over 180 min, which makes it possible for practical applications.

Relief of excited-state antiaromaticity enables the smallest red emitter

It is commonly accepted that a large π-conjugated system is necessary to realize low-energy electronic transitions. Contrary to this prevailing notion, we present a new class of light-emitters utilizing a simple benzene core. Among different isomeric forms of diacetylphenylenediamine (DAPA), o- and p-DAPA are fluorescent, whereas m-DAPA is not. Remarkably, p-DAPA is the lightest (FW = 192) molecule displaying red emission. A systematic modification of the DAPA system allows the construction of a library of emitters covering the entire visible color spectrum. Theoretical analysis shows that their large Stokes shifts originate from the relief of excited-state antiaromaticity, rather than the typically assumed intramolecular charge transfer or proton transfer. A delicate interplay of the excited-state antiaromaticity and hydrogen bonding defines the photophysics of this new class of single benzene fluorophores. The formulated molecular design rules suggest that an extended π-conjugation is no longer a prerequisite for a long-wavelength light emission.

Demonstration of a White Laser with V2 C MXene-Based Quantum Dots.

Multicolor photoluminescence over the full visible color spectrum is critical in many modern science and techniques, such as full-color lighting, displays, biological and chemical monitoring, multiband communication, etc., but the ultimate white lasing especially on the nanoscale is still a challenge due to its exacting requirements in the balance of the gain and optical feedback at different wavelengths. Recently, 2D transition metal carbides (MXenes) have emerged, with some superior chemical, physical, and environmental properties distinguishing them from traditional 2D materials. Here, a white laser with V2 C MXene quantum dots (MQDs) is originally demonstrated by constructing a broadband nonlinear random scattering system with enhanced gain. The excitation-dependent photoluminescence of V2 C MQDs is enhanced by passivation and characterized, and their localized nonlinear random scattering is realized by the generation of excitation-power-dependent solvent bubbles. With the optimized excitation, the blue, green, yellow, and red light is amplified and simultaneously lased. This work not only provides a kind of promising material for white lasers, but also a design strategy of novel photonics for further applications.

Ultraviolet photography and insect vision

Many of us teach that insects can see “invisible” ultraviolet light, but what demonstrations do we perform to illustrate this? Often UV can be used to cause fluorescence or phosphorescence, which can make its existence more visible. But, is it possible to create photographs or videos that convincingly illustrate the vision of insects? In this article we provide instruction on how to create such photographs with ultraviolet light and present an appropriate discussion of how and why insects and even some people can see beyond the visible color spectrum.

Refractive Fingerprints of Lenses: Explorations in Light Transformations

Searching for an apt visual metaphor for multiculturalism to form the cover of an exhibition catalogue in 2011, the author scanned a Canon lens using a flatbed scanner and found that the whole visible color spectrum was included in the resulting image. This serendipitous discovery led to an ongoing research project on the unique refractions of all manner of lenses.

A Comprehensive Survey of Cationic Iridium(III) Complexes Bearing Nontraditional Ligand Chelation Motifs

AbstractInvited for the cover of this issue is the group of Eli Zysman‐Colman at the Université de Sherbrooke. The cover image shows a series of cationic iridium complexes synthesized in the group’s lab with emission spanning the visible color spectrum.

Integration of the Visible Color Spectrum and the Rough Sets Theory in the Process of Expert Knowledge Extraction

paper presents the basic problems encountered in the process of expert knowledge extraction. Several experiments were carried out to compare the effectiveness of using linguistic and color data during this process. Particular attention was given to the color spectrum sets, and an example of how they can be applied in the rough sets theory is provided. The main purpose of the paper is to prove that the color spectrum scale more closely reflects people's opinions than the linguistic scale does and that it is possible to effectively integrate the color spectrum scale with the rough sets theory to extract expert knowledge. The experiments were conducted on a group of real estate specialists to obtain knowledge rules during the process of buying a building plot. Opinions were collected by questionnaire and interview. The experiments confirmed the hypothesis.

On the origin of the hierarchy of color names

One of the fundamental problems in cognitive science is how humans categorize the visible color spectrum. The empirical evidence of the existence of universal or recurrent patterns in color naming across cultures is paralleled by the observation that color names begin to be used by individual cultures in a relatively fixed order. The origin of this hierarchy is largely unexplained. Here we resort to multiagent simulations, where a population of individuals, subject to a simple perceptual constraint shared by all humans, namely the human Just Noticeable Difference, categorizes and names colors through a purely cultural negotiation in the form of language games. We found that the time needed for a population to reach consensus on a color name depends on the region of the visible color spectrum. If color spectrum regions are ranked according to this criterion, a hierarchy with [red, (magenta)-red], [violet], [green/yellow], [blue], [orange], and [cyan], appearing in this order, is recovered, featuring an excellent quantitative agreement with the empirical observations of the WCS. Our results demonstrate a clear possible route to the emergence of hierarchical color categories, confirming that the theoretical modeling in this area has now attained the required maturity to make significant contributions to the ongoing debates concerning language universals.

Use of a cytogenetic whole-genome comparison to resolve phylogenetic relationships among three species: Implications for mammalian systematics and conservation biology

The objective was to apply a novel modification of a genome-wide, comparative cytogenetic technique (comparative genomic hybridization, comparative genomic hybridization (CGH)), to study species belonging to the myrmecophagous (ant/termite eating) mammalian orders/superorders (Pholidota, Tubulidentata, Carnivora, and Xenarthra), as a model for other applications in mammalian systematics and conservation biology. In this study, CGH was applied to high-quality metaphase spreads of pangolin (Pholidota), using probes of sloth and canine (Xenarthra and Carnivora, respectively) genomic DNA labeled with different fluorophores, thereby facilitating analysis of the visible color spectrum on pangolin karyotypes. Our results posited that pholidotes are closer to carnivores than to xenarthrans, which confirmed the current consensus that myrmecophagy in these mammalian lineages was more likely because of homoplasy (convergent evolution) than being an ancestral character. Since the modified CGH technique used is genome-wide, has chromosome-level resolution, and does not need full genome sequencing, it has considerable potential in systematics and other fields.

Degradation of Orange G by Laccase: Fungal Versus Enzymatic Process

Biodegradation of the Orange G azo dye by pellets of Trametes versicolor in a fluidized bioreactor operating under conditions of laccase production was studied. The percentage of decolorization obtained was 97% in batch mode and both the biomass and the broth, were colorless. In vitro degradations carried out with purified commercial laccase from Trametes versicolor demonstrated that laccase is able to degrade the dye. In spite of the high level of decolorization reached in both processes, an important difference between the fungal and enzymatic treatments was detected. At the end of the experiments carried out in vitro, a final residual color appears (different to the initial one). Consequently, measuring the yield of decolorization as a percentage of absorbance λmax variation is not the best indicator of the treated wastewater quality, but the analysis of the visible color spectrum makes it possible to detect changes in color. The results demonstrate that better results are obtained with fungal Orange G biodegradation because a further breakdown of the enzymatic products is achieved with the fungus.

Magnetic resonance axonography of the rat spinal cord.

In spite of dramatic advancement in biomedical imaging technologies, non-invasive visualization of anatomic detail of the spinal cord has remained a major challenge. Here, a novel color-coded contrast method for magnetic resonance imaging (MRI) which provides superb resolution of the spinal cord in live animals, comparable to that of histological preparations, is described. The method, referred to here as three dimensional anisotropy (3DAC) contrast MRI, displays cross-sectional images in the full visible color spectrum, encoding directional information regarding intravoxel anisotropic water motion in space. Since neuronal fibers, especially axons, possess significantly higher intravoxel anisotropic water motion compared with other elements in the nervous system, 3DAC is highly sensitive to axonal direction and density. Axonography of the spinal cord of rats obtained using this technique showed anatomic detail at a resolution hitherto unobtainable in live animals.