Color Signals Research Articles

Assessing color cues of development, breeding status and reproductive condition in captive golden lion tamarins (Leontopithecus rosalia).

Color signals play an important role in intraspecific communication and are well studied in catarrhine primates, which exhibit uniform trichromatic vision that is well suited to detecting such signals. Platyrrhine primates exhibit polymorphic color vision with different individuals possessing different color vision types in most species. Intriguingly, some platyrrhine species exhibit bare faces, which are convergent with those of catarrhines. However, putative functions of bare-faced color signals in platyrrhines remain largely unexplored. We measured facial skin color of five captive golden lion tamarins (Leontopithecus rosalia) using color-calibrated digital photography and modeled these colors to the visual systems of the species. Our results show that facial coloration is different between infant and older adults and varies across reproductive condition, but not between breeding and nonbreeding adults. While preliminary, our study suggests that facial coloration may be involved in sociosexual signaling in golden lion tamarins, and provides intriguing evidence that we hope might stimulate more studies of bare-faced signaling in platyrrhines.

Fe(Ⅱ)-doped ZIF-67 derivatives-based composites as nanozyme for dual-mode colorimetric and fluorescent detection of SARS-CoV-2 nucleocapsid protein

The repeated outbreaks of coronavirus disease 2019 (COVID-19) have seriously threatened human health and economic development. Therefore, it is still significant to explore an efficient method for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection. Herein, we designed a dual-mode colorimetric and fluorescent immunosensor based on Fe2+ doped ZIF-67 derivatives-based composites, Pt nanoparticles loaded on CoFe nanoparticles embedded porous carbon-nitrogen hexahedron (CoFe/NC@Pt), for detecting SARS-CoV-2 nucleocapsid protein. The doping of Fe2+ generated bimetallic CoFe nanoparticles and formed more defects after pyrolysis. Meanwhile, the peroxides-like activity significantly improved owning to the synergistic effect of Co and Fe nanoparticles. Furthermore, loaded Pt nanoparticles not only provided more active sites, but also could couple antibodies by modifying functional groups. CoFe/NC@Pt exhibited good peroxidase-like activity and could catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxides in the presence of H2O2, generating visible color signals. While the oxTMB could quench the fluorescence of carbon dots through inner filter effect, thereby providing fluorescent signals. The limit of detection were 0.022 ng/mL (colorimetric) and 0.018 ng/mL (fluorescent). And the specificity of the immunosensor was verified by comparing with other interferents. Therefore, this dual-mode immunosensor with good performance provided a reliable strategy for diagnosis of COVID-19.

Development of a PCR-based lateral flow immunoassay for the identification of rainbow trout ingredient in foods

A simple PCR-based lateral flow immunoassay (LFIA) was developed in this study to identify rainbow trout ingredient in foods. This assay was developed by coupling PCR amplification of rainbow trout DNA with the detection of labeled amplicon using LFIA. The rainbow trout-specific PCR primers targeted at mitochondrial ATP6 gene were successfully designed. The color signals of LFIA could be observed by the naked eye within 5 min. The reliability of this assay was confirmed by quantitative real-time PCR (qPCR). The proposed assay could achieve an LOD at 0.1 ng/μL of rainbow trout DNA. The specificity of the primers was validated against 17 other species related to fish meat fraud and no cross-reactivity was identified, followed by successful test of commercial products for fish meat authentication. PCR-LFIA is simpler and faster than the conventional qPCR and has great potential to be applied to rapidly authenticate rainbow trout ingredient in foods.

Asymmetrically split DNAzyme-based colorimetric and electrochemical dual-modal biosensor for detection of breast cancer exosomal surface proteins

Exosomal surface proteins are potentially useful for breast cancer diagnosis and awareness of risk. However, some detection techniques involving complex operations and expensive instrumentation are limited to advance to clinical applications. To solve this problem, we develop a dual-modal sensor combining naked-eye detection and electrochemical assay of exosomal surface proteins from breast cancer. Most of existing sensors rely on aptamers recognizing exosomes and generating amplified signals at the same time, which require well-designed aptamer probes to avoid difficulties in identifying exosomes. In our work, aptamers not bound by the exosomes can serve as complete templates to induce formation of G quadruplexes. The peroxidase activity of the G-quadruplex/hemin DNAzyme catalyze substrates can generate both color and electrochemical signals. The developed dual-modal sensor offers a remarkable capability to differentiate nonmetastatic, metastatic breast cancer patients, and healthy individuals through the analysis of exosomal surface proteins. The sensor's distinctive features, including its universality, simplicity, and cost-effectiveness, position it as a promising diagnostic tool in breast cancer research and clinical practice.

Diketopyrrolopyrrole-based fluorescent probe for visualizing over-expressed carboxylesterase in fever via ratiometric imaging

Fever is the result of inflammation and the innate self-defense response of organisms, can cause abnormal changes in the activity of many enzymes in organisms, including the important carboxylesterase (CE). Monitoring the activity changes of CE in vivo during a fever will help to understand heat-related pathological mechanisms. In this paper, we designed diketopyrrolopyrrole-based ratiometric fluorescent probes DPP-FBC-P and DPP-FBO-P containing alkyl chain and diethylene glycol monomethyl ether chain respective for detection of CE. Both probes could realized fast response to CE and displayed good selectivity and high sensitivity. Compared with DPP-FBO-P, DPP-FBC-P had better biocompatibility, larger signal to noise ratio (225-fold vs 125-fold) and lower detection limit (1.6 × 10−5 U/mL vs 4.2 × 10−5 U/mL). Moreover, the probe DPP-FBC-P had been successfully applied to image the endogenous CE in HepG2 cells and solid tumors, and also visualized the over expressed CE in fever cells. Most importantly, the changes of CE level in the liver of fever mice model induced by LPS were monitored with the assistance of DPP-FBC-Pvia dual channel ratio imaging for the first time. In addition, fluorescence color signal in solution was captured by smart phone, and the linear relationship between RGB ratio (G/R) and CE concentration was established. This work will provide a potential approach for investigating the physiological and pathological processes of heat related diseases.

Optical Visualization of Cadmium Ion Using a Label-Free Nucleic Acid Aptamer for Recognition

Aptamer-based biosensors have been demonstrated to provide real-time physical and chemical signals for biomedicine, food safety, drug identification, and metal ion determination. In this study, cadmium ion (Cd2+) was determined in drinking water by color signaling using the specific binding of the aptamer and target by its regulation of the catalytic capacity of gold nanoparticles (AuNPs). When sodium borohydride (NaBH4) and a probe with a catalytic function were present, the solution containing 4-nitrophenol changed from yellow to colorless. Under optimal conditions, the naked eye was sufficient to determine Cd2+ with a limit of detection (LOD) of 5 μM. The discoloration time showed a positive correlation with Cd2+ concentration up to 30 μM. This method was label-free, efficient, rapid, and selective for Cd2+ in water without expensive instruments, suggesting practical applications.

An ultrasensitive aptasensor for exosomes detection based on biotin-streptavidin and MXenes

Exosomes derived from lung cancer typically contain the genetic information of the donor cells. Therefore, exosomes contribute to early diagnosis, treatment effectiveness evaluation, and prognosis assessment of cancer. Based on the biotin-streptavidin system and MXenes nanomaterial, a dual-effect amplification method had been developed to construct an ultrasensitive colorimetric aptasensor for detecting exosomes. MXenes can enhance the loading of aptamer and biotin as the high specific surface area. Biotin-streptavidin system can increase the amount of horseradish peroxidase-linked (HRP-linked) streptavidin, considerably boosting the color signal of the aptasensor. The proposed colorimetric aptasensor exhibited excellent sensitivity, with a detection limit of 42 particles μL−1 and a linear range of 102 to 107 particles μL−1. The constructed aptasensor showed satisfactory reproducibility, stability, and selectivity, confirming the promising application of exosomes in clinical cancer detection.

A Paper-Based Multicolor Colorimetric Aptasensor for the Visual Determination of Multiple Sulfonamides Based on Aptamer-Functionalized Magnetic Beads and NADH–Ascorbic Acid-Mediated Gold Nanobipyramids

It is crucial that simple and high-throughput methods for determining multiple, or groups of, sulfonamides (SAs) be developed since they are widely used in animal husbandry and aquaculture. We developed a paper-based multicolor colorimetric aptasensor to detect 3 SAs: sulfaquinoxaline (SQ), sulfamethoxypyridazine (SMP) and sulfamethoxydiazine (SMD). Using a broad-specificity aptamer as a bioreceptor, we reduced the growth of nicotinamide adenine dinucleotide I (NADH)–ascorbic acid (AA)-mediated gold nanobipyramids (AuNBPs) to generate a multicolor signal. We also used a paper-based analytical device (PAD) system to deposit AuNBPs for a sensitive color signal read out. The aptasensor can detect more color changes corresponding to the concentrations of SQ, SMP and SMD and has higher sensitivity, better specificity and stability. It can also be used to determine SQ, SMP and SDM individually, or collectively, or any two together with a visual detection limit of 0.3–1.0 µM, a spectrometry quantification limit (LOQ) of 0.3–0.5 µM and a spectrometry detection limits (LOD) of 0.09–0.15 µM. The aptasensor was successfully used to determine SQ, SMP and SDM in fish muscle with a recovery of 89–94% and a RSD n = 5) < 8%, making it a promising method for the rapid screening of total SQ, SMP and SDM residue in seafood.

Ce4+-based self-validated portable platform for highly selective and anti-interference visual sensing of phosphate

Construction of a convenient and multi-responsive sensor for visual and real-time detecting of phosphate (Pi) is important to monitor the eutrophication pollution or drinking water quality. Herein, we developed a highly selective and anti-interference fluorescent and colorimetric dual-mode sensor for Pi detection. Since only the Ce4+ ion was used as the center with copper nanoclusters (CuNCs) and 3,3′,5,5′-Tetramethylbenzidine (TMB) as the signal carriers, the construction of the sensor was significantly simplified. The dissociated Ce4+ showed ability of triggering the CuNCs aggregation-induced emission (AIE) and oxidase-like enzyme, independently bringing red fluorescence (AIE of CuNCs) and blue color (oxidized TMB) signals. With the presence of Pi, the strong binding between Pi and Ce4+ through P-O-Ce bond quenched both the fluorescent and colorimetric signals. More significantly, the selective and anti-interference ability were effectively improved by self-validation between fluorescent and colorimetric modes. Meanwhile, combining with smartphone, the Pi lowered at 1 μM could be visually detected. Based on the fluorescent and colorimetric outputs could be directly quantified by the naked eye, a paper-based dual-mode visualization platform was constructed. The reliable dual-mode also showed robust analysis of the Pi in environmental water, indicating its great potential as a simple and efficient tool for field monitoring.

SPIDER: A framework for processing, editing and presenting immersive high-resolution spherical indoor scenes

Today’s Extended Reality (XR) applications that call for specific Diminished Reality (DR) strategies to hide specific classes of objects are increasingly using 360° cameras, which can capture entire areas in a single picture. In this work, we present an interactive-based image processing, editing and rendering system named SPIDER, that takes a spherical 360° indoor scene as input. The system is composed of a novel integrated deep learning architecture for extracting geometric and semantic information of full and empty rooms, based on gated and dilated convolutions, followed by a super-resolution module for improving the resolution of the color and depth signals. The obtained high resolution representations allow users to perform interactive exploration and basic editing operations on the reconstructed indoor scene, namely: (i) rendering of the scene in various modalities (point cloud, polygonal, wireframe) (ii) refurnishing (transferring portions of rooms) (iii) deferred shading through the usage of precomputed normal maps. These kinds of scene editing and manipulations can be used for assessing the inference from deep learning models and enable several Mixed Reality applications in areas such as furniture retails, interior designs, and real estates. Moreover, it can also be useful in data augmentation, arts, designs, and paintings. We report on the performance improvement of the various processing components on public domain spherical image indoor datasets.

Mineralogical Associations of Sedimentary Arsenic within a Contaminated Aquifer Determined through Thermal Treatment and Spectroscopy

Sedimentary arsenic (As) in the shallow aquifers of Bangladesh is enriched in finer-grained deposits that are rich in organic matter (OM), clays, and iron (Fe)-oxides. In Bangladesh, sediment color is a useful indicator of pore water As concentrations. The pore waters of orange sediments are usually associated with lower As concentrations (<50 µg/L) owing to abundant Fe-oxides which sorb As. Using this color signal as a guide, spectroscopic measurements alongside thermal treatment were extensively utilized for analyzing the properties of both Fe-oxides and clay minerals. This study uses Fourier transform infrared (FTIR) and diffuse reflectance (DR) measurements along with thermal treatment to evaluate the solid-phase associations of As from sediment collected along the Meghna River in Bangladesh. The samples analyzed in this study were chosen to represent the various lithologies present at the study site and included riverbank sands (1 m depth), silt (6 m depth), aquifer sand (23 m depth), and a clay aquitard (37 m depth). The concentrations of sedimentary As and Fe were measured by X-ray fluorescence, and the spectroscopic measurements were taken on the samples prior to the thermal treatment. For the thermal treatment, sediment samples were placed in a preheated furnace at 600 °C for 3 h. The thermal treatment caused a deepening of reddish-brown hues in all samples, and the greatest change in color was observed in the finer-grained samples. The FTIR spectral analysis revealed that the clay minerals were composed primarily of illite, smectite, and kaolinite. The DR results indicate that the majority of Fe in sands was present as goethite; however, in the clay and silt samples, Fe was incorporated into the structure of clay minerals as Fe(II). The amount of structural Fe(II) was strongly positively correlated with the sedimentary As concentrations, which were highest in the finer-grained samples. After thermal treatment, the concentrations of As in the finer-grained samples decreased by an average of 40%, whereas the change in the As concentrations of the sand samples was negligible. These findings indicate that significant proportions of solid-phase As may be retained by OM and Fe(II)-bearing clay minerals.

Utility of Color Doppler Ultrasonography in Monitoring of a Free Jejunal Flap.

External color Doppler ultrasonography is reported to be a useful monitoring technique that is simple and noninvasive; however, details of imaging of the transferred free jejunal flap have not been reported. We reviewed our experience using external color Doppler ultrasonography to monitor a transferred free jejunal flap and examined its utility. Retrospective study. Subjects were 43 patients who underwent total pharyngolaryngectomy, reconstruction with a free jejunal flap, and color Doppler ultrasonography before, during, and after surgery between September 2017 and December 2021. During surgery, arterial thrombosis was detected up to 100% with the loss of continuous color signals in the entire circumference. After surgery, the positive predictive value was 100% for each of wiggling movement, dynamic intestinal movement, and continuous color signals in the entire circumference on color Doppler ultrasonography for detecting flap viability. Their negative predictive value was 100%, 7.1%, and 50%, respectively. During surgery, the continuous color signals in the entire circumference sign were useful with 100% negative predictive value for detecting the arterial thrombosis. After surgery, the wiggling movement sign very was useful with 100% positive and negative predictive values, enabling salvage surgery to be performed soon after detection of flap failure. 4 Laryngoscope, 133:3361-3369, 2023.

Male nuptial display colour and vocalisation appear to signal independent information in the whirring tree frog

When different modes of communication are used in combination and for example convey visual and acoustic information, they form a multimodal signal. Frogs are best known for using acoustic communication, but many species also use visual or colour signals, some of which are dynamic, and may be combined with acoustic signals. In this context, the question of whether these two modes of communication reinforce the same message or offer different information is poorly understood. Male whirring tree frogs, Litoria revelata, use a multimodal signal during courtship, which combines a vocalisation and dynamic sexual dichromatism, with nuptial display colours shifting from brown or grey to bright yellow. Here, we examined the properties of the advertisement call and nuptial colour of vocalising male whirring tree frogs and tested whether the two signals were likely to reinforce each other or convey independent information. We found only weak associations between elements of male colouration and vocalisations, suggesting that advertisement calls and nuptial colour do not reinforce each other and that the signals may instead convey different information.Significance statementDynamic nuptial colour and vocalisation in combination is a relatively common multimodal signal in frogs but is unstudied. We looked for relationships between properties of colour and vocalisation in an Australian tree frog to explore whether the two sensory modes formed backup signals or multiple messages. We did not find predictive relationships between nuptial colour and vocalisation, supporting the multiple messages hypothesis and suggesting that nuptial colour is not necessarily directed at females for the purposes of mate attraction, potentially differing from the assumed function of the vocalisation. Our study is also the first to formally characterise aspects of dynamic sexual dichromatism in the whirring tree frog (Litoria revelata) and the first to describe the advertisement call of this species in its southern distribution. Whilst we do not specifically address the function of dynamic sexual dichromatism in this species, our findings do not contradict the existing literature in respect to it being a male-male directed signal.

ISUOG Practice Guidelines (updated): fetal cardiac screening.

ISUOG Practice Guidelines (updated): fetal cardiac screening.

Color Semantics of the Cultural Landscape

A cultural landscape is the result of a continuous interaction between the surrounding natural landscape and culture. Meanings, symbols, and codes of culture are an integral part of it. This paper is a review of publications on current research over the past 20 years. The aim is to analyze the existing research practices, which are based on factual evidence and existing theoretical foundations, using an interdisciplinary approach, in order to come closer to a sufficiently holistic understanding of the coloristic semantics of the cultural landscape. Such a review and analysis of disparate studies allows for the first time the correlation of different types of cultural landscapes (urban, rural, gardens, and parks) and different types of signifier functions performed in them by color—signals, indices, iconic models, conventional signs or symbols, zero, or empty signs. The author analyzes the difference in the semantics of chromatic and achromatic colors and explores the landscape chromodynamics, namely, by creating the first-ever classification of the types and meanings of color foci of various durations—from days to decades. Color loci signs are continuously communicating in the cultural landscape, which is a field of constant “cultural explosion”, where traditional cultural meanings are transmitted and new meanings are generated. The author comes to the conclusion that color symbolism is part of the “landscape-as-text” containing certain information—“messages” of culture to itself. In these messages, color has sacral, temporal, and historical semantics, thus creating an extended semantic frame for the reproduction of cultural codes.

Trigit: A free web application for rapid colorimetric analysis of images

Color visualization is one of the fundamental aspects in advancing many scientific fields. For example, monitoring color change has been used to identify abnormalities in health, environmental, water, agricultural, and food quality. Human color vision is subjective, and objective colorimetric analysis is essential to prevent incorrect deductions. ImageJ program is commonly used to process color images. Although versatile, ImageJ is neither designed nor optimized for color extraction and analysis. As such, the color extraction process is slow and the user interface is not intuitive. To streamline this process, we designed Trigit (http://trigit.com.au) as a free, rapid, and user-friendly web app to quantify color signals from images. The estimated analysis time is ∼1.5 min for new users and <20 s for experienced users, independent of the color space (CIELAB, HSV, CMYK, RGB, HEX). Compared to ImageJ, Trigit is 4–9 times and 10–15 times faster in extracting RGB and non-RGB color values, respectively, in a format that can be easily exported to a Microsoft Excel program. Trigit can be pre-downloaded into portable drives to enable use without internet access. Trigit can also be accessed from smartphones for on-site color extraction. We believe that Trigit's intuitive and rapid color extraction capability could accelerate the advancement of colorimetric technologies by alleviating the unnecessary time spent during color extraction.

Flowering phenology of species with similar flower colours in species-rich communities

Within a community, co-occurring plant species are expected to diverge in floral display or flowering phenology to decrease interspecific competition and thus increase intraspecific pollination. However, co-occurring species can also benefit from floral signal standardisation (similar colour signals among flowers of different species) because it facilitates pollinator attraction. Considering the interaction of flower colour display and flowering phenology, we investigated the visual similarity of rewarding flowers among species from highly diverse tropical and temperate vegetation types. For six groups of co-occurring, closely related bee-pollinated species with similar floral displays from Brazilian campo rupestre (51 species) and Spanish Mediterranean vegetation (30 species), we first investigated whether flower colours can be discriminated by bees based on colour locus distance in the bee vision hexagon. We then tested whether flowering phenology overlapped or was segregated. We found that within both vegetation regions, flower colour was generally not distinguishable within groups by bees. The small perceptual distance of colour loci in the bee visual space did not enable discrimination. The flowering periods of the Mediterranean species overlapped, while the Brazilian campo rupestre species tended to have segregated phenologies. Mediterranean species may benefit from the increased standardisation of signals displayed during the short flowering season, while the sequential flowering phenology of campo rupestre species may decrease interspecific competition and help maintain a recognizable signal for bees over time, favouring flower constancy. We concluded that the standardisation of the floral colour signal within these two species-rich plant communities is advantageous for most of the species studied, despite having different flowering phenologies.

Metabolomic and Transcriptomic Analysis Reveal the Role of Metabolites and Genes in Modulating Flower Color of Paphiopedilum micranthum.

Food-deceptive flowers primarily use visual signals (such as color) to mimic model plants and deceive insects into achieving pollination. Paphiopedilum micranthum is a food-deceptive orchid that has a pink labellum and two purple petals with a yellow base and has been proven to be pollinated by bumblebees. However, the chemical and molecular bases of the floral color are not well understood. We conducted targeted metabolite profiling and transcriptomic analysis to determine the color signal and its genetic basis in P. micranthum. We found that both anthocyanins and carotenoids contribute significantly to the formation of floral color that determines the color signal. Higher concentrations of anthocyanins (cyanidin and peonidin) and carotenoids (primarily lutein and zeaxanthin) were detected in the petal compared to the labellum. The upregulation of structural genes of CHS, F3'H, DFR and ANS on the anthocyanin biosynthesis pathway in petals was identified, as well as three genes of LCYE, BCH, and CCD4 on the carotenoid biosynthesis pathway. Furthermore, we discovered that three R2R3-MYBs and one bHLH transcription factors were co-expressed with the expression of different genes. These genes and transcription factors may be responsible for the spatial color difference of P. micranthum. Our study emphasizes that the color of this food-deceptive orchids is achieved through specific genes and transcription factors associated with the pigment biosynthesis pathway.

Ink Colors as Additional Stimuli in Digit Span Test: A Theoretical Approach

Part of the people around us have been proven to own synesthesia, a fascinating ability to experience two or more kinds of sensual feeling when only stimulated by one kind of sense organ. The author as synesthetes will detect some unique color when seeing every single figure. This article will discuss whether this connection between color and figure can help common people get a better memory of numeric strings. The participant will be asked to do some basic arithmetic drills which are written in figures with different colors. Then the digit span test will be operated in three different forms. That is the numeric string whose figures are all in black for the first; a one-to-one correspondence between colors and numbers for the second. This one-to-one correspondence should be in the same regulation as the arithmetic drill. The third one would be those colorful figures with a different congruent relationship to that in the arithmetic drills. The result will be recorded to show will the extra color signal influence the memory.

Photochromic Tungsten Oxide Quantum Dots-based Fluorescent Photoswitches towards Dual-mode Anti-counterfeiting Application

Development of new anti-counterfeiting technology to increase the difficulty of imitation and decoding is becoming increasingly important, but still remains challenging yet. In this work, we report the design of new fluorescence photoswitches based on photochromic tungsten oxide quantum dots (WO3 QDs) for dual-mode anti-counterfeiting applications. Complexing photochromic WO3 QDs with fluorescent gold nanoclusters (AuNCs) enables the construction of a photoswitchable fluorescence system (WO3-AuNCs) based on fluorescence resonance energy transfer. Detailed spectral and photophysical characterization showed that WO3 QDs well-retain the photochromic properties within the WO3-AuNCs composite. Importantly, photoresponsive and highly reversible switching of both color and fluorescence signals was successfully achieved by simply alternating the irradiation with UV and visible light. Potential utility of photoswitchable WO3-AuNCs composite as novel dual-mode anti-counterfeiting materials has been successfully demonstrated, including photoswitchable ink, rewritable paper and number encryption. Compared with other anti-counterfeiting materials, the present photochromic WO3 QDs-based fluorescent switches are easily synthesized and handled, and they can provide dual security mode (color and fluorescence). This work provides a generable WO3 QDs-assisted strategy of fabricating advanced fluorescence photoswitches for versatile optical counterfeiting applications.