Primary Colors Research Articles

Processable Circularly Polarized Luminescence for the Synthesis of Chiral Plasmonic Nanoparticles

AbstractCircularly polarized light is previously shown as a chiral bias to enable the synthesis of chiral plasmonic nanomaterials through light‐matter interactions. The traditional approach for circularly polarized light generation relies on a “top‐down” approach by removing undesired light polarization through optics, which suffers from energy loss and compatibility issues. An alternative approach is to develop chiral phosphors that emit efficient circularly polarized luminescence (CPL). However, most materials fail to produce processable CPL with both high quantum yield and dissymmetry factors, let alone the synthesis of chiral nanomaterials. Herein, a liquid‐crystal‐templated framework is developed to assemble halide perovskite nanocrystals, CsPbX3 (X = Cl, Br, I), and achieved efficient CPL with the record‐high figure of merit (FM) for three primary colors (Red, Green, Blue). The fidelity of the CPL is further demonstrated in the synthesis of chiral gold nanoparticles, where a five‐fold increase in optical activity is achieved.

An image encryption algorithm for colour images based on a cellular neural network and the Chua's chaotic system

In the internet era, image encryption technology plays a crucial role in ensuring the security of image information. Aiming at the problem that low-dimensional chaotic encryption has a relatively small key space and is vulnerable to chosen-plain attacks, this paper proposed a novel colour image block encryption algorithm based on the cellular neural network and the Chua's chaotic system. Firstly, the plain is separated into three primary colours. And Fourier transform is applied to achieve optical transformation, generating six chaotic sequences iteratively. Secondly, the chaotic sequences were combined in pairs. And then combined with the plain to form three sequences, which were used in the diffusion process. Finally, the improved Chua's chaotic system is used to scramble the image. Both diffusion and scrambling are performed synchronously during encryption. Through the above operation, we get the final colour encrypted picture. The experimental results show that the algorithm has excellent encryption effect and can resist common attacks.

Development of a New Non-Destructive Analysis Method in Cultural Heritage with Artificial Intelligence

Cultural assets are all movable and immovable assets that have been the subject of social life in historical periods, have unique scientific and cultural value, and are located above ground, underground or underwater. Today, the fact that most of the analyses conducted to understand the technologies of these assets require sampling and that non-destructive methods that allow analysis without taking samples are costly is a problem for cultural heritage workers. In this study, which was prepared to find solutions to national and international problems, it is aimed to develop a non-destructive, cost-minimizing and easy-to-use analysis method. Since this article aimed to develop methodology, the materials were prepared for preliminary research purposes. Therefore, it was limited to four primary colors. These four primary colors were red and yellow ochre, green earth, Egyptian blue and ultramarine blue. These pigments were used with different binders. The produced paints were photographed in natural and artificial light at different light intensities and brought to a 256 × 256 pixel size, and then trained on support vector machine, convolutional neural network, densely connected convolutional network, residual network 50 and visual geometry group 19 models. It was asked whether the trained VGG19 model could classify the paints used in archaeological and artistic works analyzed with instrumental methods in the literature with their real identities. As a result of the test, the model was able to classify paints in artworks from photographs non-destructively with a 99% success rate, similar to the result of the McNemar test.

Facial skin color assessment and proposed skin shade guide for maxillofacial prosthesis using cluster analysis in a cohort of Indian adults

Aim: The precise estimation and replication of skin color are crucial for maxillofacial prosthesis. The study aimed to evaluate facial skin color with a colorimeter and suggest a skin shade guide and formula for color estimation. Settings and Design: An observational study conducted in the department of prosthodontics. Materials and Methods: Study was conducted on 368 individuals of Indian origin in age range of 20–45 years. The facial skin color was assessed in malar regions using SkinColorCatch colorimetric device and individual topography angle (ITA) and CIELAB L*a*b* values were noted. Statistical Analysis Used: K-means clustering was utilized to propose a shade guide for maxillofacial prosthesis with 24 skin shades. Logistic regression analysis was conducted to propose a formula to estimate skin shade of the individuals. Results: Based on cluster analysis, 368 subjects were divided into three clusters with similar characteristic as Cluster 1 with dark skin color in 88 (23.91%) subjects, Cluster 2 with medium skin color in 224 (60.87%) subjects, and Cluster 3 with light skin color in 56 (15.22%) subjects. The mean ITA and L*a*b* values for cluster 1 were −47.04° ±14.77°, 34.53 ± 4.31, 8.55 ± 2, 11.42 ± 3.7033, respectively. The mean ITA angle and L*a*b* values for Cluster 2 were 4.29° ±11.34° 51.67 ± 3.42, 8.79 ± 3.13, 21.36 ± 2.38, respectively. The mean ITA and L*a*b* values for Cluster 3 were 34.65 ± 4.29°, 62.66 ± 3.08, 6.53 ± 1.79, 17.73 ± 2.39, respectively. The proposed shade guide comprised a total of 24 different shades that were categorized into three primary colors according to three distinct clusters, each of which was further broken down into eight subclusters containing various shades within each cluster. Logistic regression analysis gave an equation as follows: Y =12.43 + 0.186X (Y = Predicted skin color, X = ITA angle). Conclusions: Twenty-four facial skin shade tabs have been proposed based on ITA angle and CIELAB values. This comprehensive approach to categorize the shades will ensure a detailed and organized system for selecting and matching colors in maxillofacial prosthesis.

The bio–accumulation and –magnification of microplastics under predator–prey isotopic relationships

Recent studies on microplastics (MPs) in marine ecosystems have focused on their bioaccumulation and biomagnification within food chains, emphasizing their potential health risks to humans. However, these bio-effects of MPs in marine ecosystems remain a contentious issue. Employing the "consumer–dietary source" tracking function in stable isotope analysis can enhance our comprehension of how MPs magnify in organisms. In our research conducted in the coastal waters of Haizhou Bay, Jiangsu, China, we examined two commercially important fish species, Larimichthys polyactis and Collichthys lucidus, through stable isotope analysis to investigate the accumulation of MPs in their dietary sources. Results revealed fiber, blue, and PET as the primary shapes, colors, and polymers of MPs in the region. C. lucidus displayed a broader isotopic niche and a higher propensity for MP accumulation than L. polyactis. Biomagnification analysis indicated that dominant MP shapes, colors, and polymers were magnified in both fish species, with MPs smaller than 3 mm exhibiting substantial biomagnification. Factors such as feeding strategies and habitat preferences may influence MP ingestion by fish. We conclude that a high proportion of dietary sources in fish does not necessarily equate to a high concentration of MPs. Neglecting the proportion of dietary sources might lead to underestimating MP biomagnification. Therefore, a multidimensional approach to exploring the biomagnification of MPs is essential to accurately grasp this unique pollutant's impact.

Yellow-transmissive blue electrochromic polymers based on triphenylamine and ProDOT derivatives

Electrochromic polymer with yellow hue is few relative to those with other two primary colors due to its optical absorption at short wavelength of ≈ 450 nm. Triphenylamine (TPA) and its derivatives (TPAs) as chromogenic groups are frequently used to construct neutral yellow electrochromic polymers, however, those polymers based on TPAs usually exhibit low transmittance at oxidation state due to the residual absorption at short wavelength. Here, three neutral yellow electrochromic polymers (PBBE-1, PBBE-2 and PBBE-3) with different content ratios of ProDOT-10, TPA-4 and benzene were synthesized by Suzuki coupling reaction. With ProDOT-10 content in polymeric chain increasing, the oxidation potentials of polymers decrease gradually. Due to the twisted molecular structure, the absorption peaks of polymers almost remain unchanged when ProDOT-10 content in polymer reaches critical value, which provide an effective method for preparing neutral yellow electrochromic polymers. During oxidation process, PBBE-1 turns to black; PBBE-2 turns to dark blue; PBBE-3 turns to light grey, further to light blue. Through optimizing TBA-4/ProDOT-10 ratio, the electrochromic properties of polymers have been improved, such as optical contrast, response time and coloration efficiency. Especially, PBBE-3 possesses 40 % optical contrast at 435 nm, which is higher than reported TPAs based polymers at short wavelengths.

Multi-color emission composites of white carbon dots and dyes through inner filter effect

A series of multi-color carbon dot composites were obtained by transforming white carbon dots (WCDs) into three primary colors using the dyes' inner filter effect (IFE). WCDs were combined with three distinct dyes (methyl red, bromocresol green, and methylene blue), and three fluorescence colors (red, yellow, and blue) were obtained. The colors of the emitting light excited by the same UV light were similar to the colors of the respective dyes, and have a large Stokes shift. The presence of the IFE between WCDs and dyes was proved through a variety of methods, the analysis of the relationship between the UV of dyes and fluorescence spectra of WCDs, the excitation-emission matrix, as well as the comparison PL decay profiles of WCDs before and after dye addition. The Stern-Volmer quenching constant KSV exhibited no temperature dependence during the IFE process with increasing concentrations of dyes. The UV spectra of the mixture of WCDs and dyes were simply the sum of two individual components, which implies that there is no chemical interaction between WCDs and dyes. Since methyl red and bromocresol green are acid-base indicators, the fluorescence color of the carbon dot composite also changed continuously during the dilute NaOH solution titration process. In furtherment, distributing the binary system of “WCDs + dye” within poly (vinyl alcohol) (PVA), three colors fluorescent composite films of “WCDs / Dye / PVA” were produced successfully.

Bright Structural-Phase-Pure CsPbI3 Core-PbSO4 Shell Nanoplatelets With Ultra-Narrow Emission Bandwidth of 77 meV at 630 nm.

Achieving a narrow emission bandwidth islong pursued for display applications. Among all primary colors, obtaining pure red emission with high visual perception is the most challenging. In this work, CsPbI3 halide perovskite nanoplatelets (NPLs) with rigorously controlled 2D [PbI6]4- octahedron layer number (n) are demonstrated. A perovskite core-PbSO4 shell structure is designed to prevent aggregation and fusion between NPLs, enabling consistent thickness and quantum confinement strength for each NPL. Consequently, exact n = 4 CsPbI3NPLs are demonstrated, exhibiting emission peaks around 630nm, with very narrow spectral bandwidths of <24nm and high absolute photoluminescence quantum yields up to 85%. The emission of n = 4 NPLs falls exactly within the pure-red region, closely aligning with the International Telecommunication Union Recommendation BT.2020 standard. Measurements suggest predominant stability and color homogeneity compared to traditional red-emitting CsPbIxBr3- x nanocrystals. Finally, proof-of-concept pure-red emissive light-emitting diodes (LEDs) are demonstrated by integrating n = 4 CsPbI3 NPLs films with a blue LED chip, showing an excellent external quantum efficiency of 18.3% and high brightness exceeding 3 × 106 nits. Stringent requirements for future display technologies, are satisfied based on the high color purity, stability, and brightness of CsPbI3 NPLs.

Ultrafast Response and Broad Detection Range of a Ternary Cation Perovskite Single-Crystal Thin Film Photodetector for Imaging.

FA-MA-Cs ternary cation perovskite exhibits excellent optoelectronic properties and high stabilities against humidity and light soaking and thus has aroused extensive attention in polycrystalline thin film solar cells. Compared with polycrystalline counterparts, FA-MA-Cs ternary cation perovskite single-crystal thin films (SCTFs) have lower defects, better carrier transport capacity, and stability because of lacking grain boundary defects. However, the immature growth technology of SCTFs restricts digging out its optoelectronic potential. Here, we proposed an improved space-confined method to grow large area FA0.9 MA0.05Cs0.05PbI2.7Br0.3 SCTFs using a tunable heating area to control the nucleation and growth process. Its area reaches 64 mm2 with a thickness of 26 μm. The SCTF exhibits high crystallinity, low defect density, long carrier lifetime, and high moisture resistance stability. Besides, a photosensitive chip based on a planar metal-semiconductor-metal photodetector demonstrates linear response to the three primary colors, with a photosensitive range that is 1.5 times that of protocol 3 wide color gamut. Under high-frequency light sources, the on/off ratio reaches 3.9 × 103, and the response time can be as low as 400 ns. Such ultrafast response speed and broad photosensitive range are successfully achieved for imaging applications.

Exploring the impact of logo colors on the perceived tastes of tea beverages—A study on hand-shaken beverages in Taiwan

Color visually communicates the product’s flavors to consumers and further influences their taste perception. This study explores the perceived taste of tea beverages caused by the logo’s principal colors, using hand-shaken tea beverages in Taiwan as an example. To identify the linkage between the logo color and tea tastes, this study divides the taste of tea beverages into four categories: sweetness, freshness, bitterness, and astringency. Then, the 69 tea beverage logos are allocated into the 14 color sections in the CIELAB color space according to their primary colors. The Correspondence Analysis method is employed to visualize the relationships between the logos and the perceived tastes. The tea tastes are then mapped into the color sections in the CIELAB color space. The analysis results reveal that the sweetness links to logos in the Warm Scheme colors (hue angle from 0 to 59 degrees). The fresh taste is bound with the logo with the Cool White Scheme colors (hue angle from 90 to 149 degrees and brightness &gt;80). Finally, the bitter and astringent tastes link to the logo colors in the Cold Black Scheme colors (hue angle from 60 to 89 degrees, 150 to 329 degrees, and brightness &lt;25). This study expands the color and taste association literature from general food to tea beverages. Our obtained empirical results can be applied to hand-shaken beverage companies to select principal colors for designing logos and packages that align with tea beverages’ perceived tastes to convey brand recognition accurately.

Color Analysis of Brocade from the 4th to 8th Centuries Driven by Image-Based Matching Network Modeling

To achieve the color matching rules for the textiles discovered during Silk Road excavations between the 4th and 8th centuries, this research proposed an image-based matching network modeling method. The Silk Road facilitated trade and cultural exchange between the East and West, and the textiles found along the way depict the development of fabrics in a color scheme with great cultural significance. A total of 165 images with brocade patterns were collected from a book with a detailed description of the Western influences on textiles along the Silk Road. Two different clustering methods, including the K-means clustering method and octree quantization approach, were used to extract the primary and secondary colors. By combining the HSV color space with the PCCS color system, the color distribution was analyzed to discover the features of representative color patterns. The co-occurrence relationship of the auxiliary colors was explored using the Apriori algorithm, and a total of eight association rules were established. The results showed that the K-means clustering algorithm can show a better effect of color classification to obtain three primary colors and nine secondary colors. The matching mechanism with a visualized network model was also proposed, which showed that reddish-yellow tones are the main colors in the brocade patterns, and the light and soft tones separately account for 27% and 20%. Beige and brown are the most common colorways, with a confidence level of 47%. One style of brocade pattern was used to demonstrate different appearances within various color networks, which could be applied to 3D virtual fitting. This image-based matching network modeling approach makes the color matching schemes visible, and can assist fashion design with fabric features influenced by historical and cultural development.

Toward Controllable Self‐Reduction of Mn4+ to Mn2+ by Lanthanide Ions for Luminescence Based Colorimetric Sensing of Temperature

AbstractLuminescence intensity ratio (LIR) based optical thermometers have attracted lots of attention. In case of color tunable luminescence with the variation of LIR, “RGB colorimetry” based on convenient temperature sensing using a smartphone or digital camera is available. However, narrow emission bands with primary colors are needed for avoiding color crosstalk and achieving high sensitivities. In this paper, Mn4+ and Mn2+ coactivated CaAl12O19 (CAO) phosphors are reported that show a narrow red emission of Mn4+ and green one of Mn2+ with the number of the two ions controlled by lanthanide ions through manipulation of self‐reduction of Mn4+ to Mn2+ in air. The self‐reduction in CAO via the addition of Ce4+ is mainly studied. First‐principles calculation shows that the self‐reduction is driven by Ca vacancies that are produced in aliovalent substitution of Ce4+ for Ca2+ and can reduce the formation energy of Mn2+. The comparative study of temperature sensing based on LIR and RG colorimetry is conducted. The relative sensitivity based on LIR is high as 4.5% K−1 at 373 K and that for RG colorimetry can reach 2% K−1 at 350 K. These findings provide a strategy for manipulation of manganese valance states and a phosphor for RG colorimetry temperature sensing.

A Photoelectrochemical Retinomorphic Synapse.

Reproducing human visual functions with artificial devices is a long-standing goal of the neuromorphic domain. However, emulating the chemical language communication of the visual system in fluids remains a grand challenge. Here, a "multi-color" hydrogel-based photoelectrochemical retinomorphic synapse is reported with unique chemical-ionic-electrical signaling in an aqueous electrolyte that enables, e.g., color perception and biomolecule-mediated synaptic plasticity. Based on the specific enzyme-catalyzed chromogenic reactions, three multifunctional colored hydrogels are developed, which can not only synergize with the Bi2S3 photogate to recognize the primary colors but also synergize with a given polymeric channel to promote the long-term memory of the system. A synaptic array is further constructed for sensing color images and biomolecule-coded information communication. Taking advantage of the versatile biochemistry, the biochemical-driven reversible photoelectric response of the cone cell is further mimicked. This work introduces rich chemical designs into retinomorphic devices, providing a perspective for replicating the human visual system in fluids.

Eksperimen Pencampuran Warna Dalam Meningkatkan Keterampilan Sains Pada Anak Usia Dini

This research, conducted by Saya Ani Mulyani, aims to optimize the use of simple science experiments, especially in the context of color mixing, to increase learning creativity in young children. The research method used is qualitative research. The participants in this research were 14 children aged 4-5 years from an early childhood education institution. The intervention was carried out in the form of a simple science experiment involving mixing primary colors. Data was collected through participant observation during the intervention, interviews with teachers, and reflective notes. Data analysis was carried out using a qualitative approach in Kober At-Taubah, Kp. Ciawitali, Pasanggrahan Village, District. Sukawening, Kab. Garut, West Java. The research results show that the use of simple science experiments in early childhood learning can increase their learning creativity. Children show a high interest in experimental activities, as well as the ability to generate new and creative ideas in exploring color mixing. Additionally, interaction between children also increases, allowing them to learn from each other and develop their social skills. These findings highlight the importance of using interesting and experience-based learning approaches in developing creativity in early childhood. The practical implication of this research is the need to integrate simple science experiments into the early childhood education curriculum as a means of stimulating PAUD creativity.

High-transmission dual-tunable structural color based on an all-dielectric medium

In this paper, we propose a three-layer all-dielectric structure capable of dynamic tunability by varying the lattice period and incident angle, thereby facilitating the production of high-quality colors. By integrating three dielectric layers with outer rings and inner cylinders, we effectively suppress multimodal spectra, leading to significantly improved transmission rates for the CMY primary colors. The high transmission efficiency for magenta reaches 96 %, yellow reaches 89 %, and cyan attains an outstanding 99 %. The materials utilized in this design possess characteristics conducive to practical fabrication, thereby offering extensive possibilities for practical applications. Furthermore, our findings provide new insights and potential avenues for future research and applications of structural colors in all-dielectric materials.

Low blue-hazard white-light emission based on color-tunable triplet-triplet annihilation upconversion

The commonly used artificial light sources, such as fluorescent lamps and white light-emitting diodes, often have a high ratio of blue light emission, which poses potential blue light hazards, especially one of the main culprits leading to eye diseases. Therefore, developing novel white lighting sources with low blue-hazard is highly appreciated. In this work, an air-stable and color-tunable triplet–triplet annihilation upconversion (TTA-UC) mechanism was proposed to realize the low blue-hazard white-light emission. The proposed design was composed of three primary RGB colors from the annihilator (9,10-diphenylanthracene, DPA), the laser excitation source, and the photosensitizer (palladium (II) octaetylporphyrin, PdOEP), respectively. The introduction of oil-in-water (o/w) microemulsion can effectively block the potential oxygen-induced triplet-quenching and benefit high UC efficiency. Moreover, either raising ambient temperatures or adding isobutanol can activate the UC process to yield white-light emission. Notably, the white-light emission with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.33, 0.33) as well as a low ratio of blue emission (14.2 %) was achieved at an ambient temperature of 42 °C. Therefore, the proposed air-stable TTA-UC mechanism can significantly lower the blue-hazard and provide a novel solution for applications in lighting and display.

(Invited) Blue Organic Light-Emitting Diode Using Dynamic Exciton for Low Driving Voltage

Among the three primary colors, blue emission in organic light-emitting diodes (OLEDs) are highly important but very difficult to develop. OLEDs have already been commercialized; however, blue OLEDs have the problem of requiring a high applied voltage due to the high-energy of blue emission. Herein, an ultralow voltage turn-on at 1.47 V for blue emission with a peak wavelength at 462 nm (2.68 eV) is demonstrated in an OLED device. This OLED reaches 100 cd/m2, which is equivalent to the luminance of a typical commercial display, at 1.97 V. Blue emission from the OLED is achieved by the selective excitation of the low-energy triplet states at a low applied voltage by using the charge transfer (CT) state as a precursor and the triplet-triplet annihilation, which forms one emissive singlet from two triplet excitons. We found that the essential component for efficient blue emission is a smaller energy difference between the CT state and triplet exciton, accelerating the energy transfer between the two states and achieving the optimal performance by avoiding direct decay from the CT state to the ground state. Our study demonstrates that the developed OLED allows for a much longer operation lifetime than that from a typical blue phosphorescent OLED because the blue emission originates from a stable low-energy triplet exciton that avoids degrading the constituent materials.

Brainwave and Emotional Responses of Male and Females to Munsell’s Five Primary Colors

Purpose: The goal is to use quantified EEG and emotional responses to objectively assess the effects of color using gender-specific EEG data, as well as to analyze emotional responses concerning the psychological effects of color modulation. This study intends to apply these findings in various fields. Through this, we hope to better understand how color stimuli affect cognitive responses, brain activity, and emotional regulation.Methods: In this study, we evaluated the EEG and emotional responses to five basic color stimuli in male and females in their 20s. EEG analysis was performed using the Coefficient of Variation for the Brainwaves (CVBs), which is the ratio of the relative brainwave power difference to the baseline brainwave. The five colors were specified using the Munsell notation and RGB values. Emotional responses were evaluated using 10 pairs of adjectives to calculate the preference index(PI), average preference index(API), and favorability. The EEG and emotional evaluations were statistically analyzed using repeated-measures ANOVA in SPSS 22.Results: The EEG responses to the five-color stimuli revealed that both male and female experienced increased concentration and arousal with the red (R) and purple (P) stimuli. Colors yellow (Y) and green (G) caused relaxation and comfort in both genders. While male and females had different emotional responses to each color, the reactions were generally similar. Both male and females preferred the color R, while Y and P were equally popular. Color R significantly activated β and γ waves associated with concentration and arousal in both genders. Warm colors were found to elicit arousal, while cool colors induced feelings of comfort, as evidenced by EEG and emotional responses. The findings showed that EEG and emotional responses to color stimuli were similar across genders and that color had a significant and meaningful impact on brainwaves and emotions.Conclusion: The quantified findings of color-based brainwaves and emotional responses can be applied to various fields that use colors. By leveraging these findings, color perception is expected to have a strong influence on human brain activity and emotional regulation.

Dermoscopy of skin metastases in advanced cancer-systemic (visceral, hematologic) and cutaneous.

Skin metastases arise in 10% of cancer patients, but standardized dermoscopy diagnostic criteria for skin metastases remain poor. This study's objective was to analyze the dermoscopy features of skin metastases from advanced systemic and cutaneous cancers. A retrospective study on 715 dermoscopy images of skin metastases from 33 patients with various primary cancers (breast, ovary, melanoma, non-melanoma skin cancer, and chronic leukemia) attending two academic centers between 2013 and 2023 was performed. Four independent observers blindly analyzed patterns, colors, vessels, and elementary lesions for each metastasis (30 parameters in total). The structureless white pattern was the most prominent indicator of cutaneous metastasis (81.26%, p < 0.001). Regardless of the primary tumor, colors pink, red, white, and tan were identified. Elementary lesions were infrequent, except for melanoma metastases that displayed dots (13.23%) and globules (11.11%). Breast cancer metastases presented: blue (41.48%) and red (34.32%) colors, irregular vessels (13.58%), and a blue-naevus pattern (22.22%). Melanoma metastases displayed: a blue-naevus pattern (61.38%), a blue color (85.71%), and a structureless-blue combination pattern (79.37%). Non-melanoma skin cancer metastases were characterized by vascular (42.11%) and angioma-like (31.58%) patterns, pink (57.89%) and red (57.89%) colors, irregular (57.89%), thin hairpin (47.37%), comma (47, 37%), and thick hairpin (26, 32%) vessels and a red, white and irregular vessels combination pattern (52, 63%). A pink structureless combination pattern was frequent (61.05%) in chronic leukemia metastases. Ovarian cancer metastases displayed a white and tan structureless combination pattern (100%) and frequently had dotted vessels (42.85%). Papules and nodules with a white structureless pattern suggest skin metastases, regardless of the primary tumor. A blue structureless lesion is indicative of melanoma metastasis and a vascular pattern with irregular vessels indicates a non-melanoma skin cancer metastasis. Dermoscopy stands as a reliable non-invasive diagnostic method for suspected cutaneous metastases in patients with a known cancer history.

Effect of Three Bleaching Protocols on Tooth Discoloration Caused by Hemoglobin.

Objectives: This study assessed the efficacy of different combinations of oxalic acid, 35% hydrogen peroxide, and 5.25% sodium hypochlorite (NaOCl) for bleaching of tooth discolorations caused by hemoglobin. Materials and Methods: In this in vitro study, 40 sound extracted human premolars were disinfected and decoronated. Their primary color parameters were measured (T1). The teeth were then centrifuged with human blood for 3 days, rinsed, polished, and their color parameters were measured again (T2). They were randomly divided into 4 groups (N=10) and treated as follows: Group A: in-office bleaching with Pola-Office Plus followed by 30 seconds of light-curing, group B: 0.24 M oxalic acid for 5 minutes followed by in-office bleaching, group C: 5.25% NaOCl for 5 minutes followed by in-office bleaching, and group D: 0.24 M oxalic acid (5 minutes) followed by 5.25% NaOCl (5 minutes) and subsequent application of in-office bleaching gel. The color parameters of the teeth were measured again (T3). Data were analyzed by one-way ANOVA and paired sample t-test (alpha=0.05). Results: T2-T3 ∆E in groups B and D was significantly higher than that in group A (P<0.05); the difference between groups B and D was not significant. The mean ∆E and ∆L in group C were not significantly different from those in group A (P>0.05). ∆L significantly and equally increased in groups B and D after bleaching. Conclusion: Application of oxalic acid followed by in-office bleaching gel is more effective than the bleaching gel alone for correction of tooth discolorations caused by hemoglobin.