Original Color Research Articles

Effects of variable-temperature drying on the qualities and sweet-substance profile of Zizyphus jujuba Mill. cv. Junzao

The changes in the qualities and sweet-substance levels of Junzao jujube during variable-temperature drying (VTD) were investigated. The results showed that VTD retains the original color of jujube, reduces its hardness and chewiness, and decreases its wrinkling while shortening the drying time by 13.2% compared with that of constant temperature drying (CTD). “Electronic-tongue” taste analysis showed that the sweetness of VTD jujube is significantly higher than that for CTD. This is shown to be related to the contents of sucrose, fructose, and glucose, as well as the activities of invertase and sucrose synthase enzymes. In addition, the content trends for sweet amino acids are correlated with the temperature gradient used in VTD. Thus, the present study elucidates the factors governing the transformation of sugar substances in jujube during VTD, as well as providing a practical reference for the application of VTD in the jujube industry.

Effect of Different Drying Methods on the Quality of Oudemansiella raphanipes.

In this study, we used fresh Oudemansiella raphanipes as raw materials and pre-treated through hot air drying (HD), infrared radiation drying (ID), and vacuum freeze drying (VD) to investigate the effects of different drying methods on the rehydration rate, appearance quality, microstructure, and volatile flavor components of the dried products, as well as to determine the physicochemical properties and bioactivities of the polysaccharides in the dried O. raphanipes. The results showed that the VD O. raphanipes had the highest rehydration rate and the least shrinkage in appearance, and it better maintained the original color of the gills, but their aroma was not as strong as that of the HD samples. The scanning electron microscopy results indicate that VD maintains a good porous structure in the tissue, while HD and ID exhibit varying degrees of shrinkage and collapse. Seventy-five common volatile substances were detected in the three dried samples, mainly alkanes, alcohols, and esters. The polysaccharides (PS-H, PS-I, and PS-V) extracted from the dried samples of these three species of O. raphanipes had similar infrared spectral features, indicating that their structures are basically consistent. The highest yield was obtained for PS-V, and the polysaccharide content and glucuronic acid content of PS-I were higher than those of the remaining two polysaccharides. In addition, PS-V also showed better antioxidant activity and inhibitory activity against α-glucosidase as well as α-amylase. In conclusion, among the above three drying methods, the quality of O. raphanipes obtained by vacuum freeze drying is the best, and this experiment provides a theoretical basis for the selection of drying methods for O. raphanipes.

A binarization method for logos

In the field of digital image processing, the binarization of logo images presents a significant challenge due to the diversity in their color distribution and graphical structures. Logos, as distinctive visual symbols, are integral to brand recognition and commercial advertising. Traditional binarization methods often struggle with this diversity, leading to difficulties in preserving the original color and details of the images. To address this issue, this paper introduces a novel binarization approach specifically designed for logo images. The method comprises three stages: preprocessing, binarization, and noise removal. In the binarization stage, the Otsu method is adapted from a global to a local thresholding technique, combining both global and local thresholds for each pixel. The efficacy of this method is demonstrated through comparative experiments with logos of varying colors and structures, showing superior performance in maintaining image color and detail restoration over traditional methods. Additionally, the preprocessing and noise removal steps further enhance the method's effectiveness in handling logos with rich background colors and complex details. Overall, this approach proves to be highly adaptable across a wide range of logo types.

Estimation of wheat protein content and wet gluten content based on fusion of hyperspectral and RGB sensors using machine learning algorithms

The protein content (PC) and wet gluten content (WGC) are crucial indicators determining the quality of wheat, playing a pivotal role in evaluating processing and baking performance. Original reflectance (OR), wavelet feature (WF), and color index (CI) were extracted from hyperspectral and RGB sensors. Combining Pearson-competitive adaptive reweighted sampling (CARs)-variance inflation factor (VIF) with four machine learning (ML) algorithms were used to model accuracy of PC and WGC. As a result, three CIs, six ORs, and twelve WFs were selected for PC and WGC datasets. For single-modal data, the back–propagation neural network exhibited superior accuracy, with estimation accuracies (WF > OR > CI). For multi-modal data, the random forest regression paired with OR + WF + CI showed the highest validation accuracy. Utilizing the Gini impurity, WF outweighed OR and CI in the PC and WGC models. The amalgamation of MLs with multimodal data harnessed the synergies among various remote sensing sources, substantially augmenting model precision and stability.

Plume mode instability enhanced by emitter surface poisoning in hollow cathode

The unstable plume mode of hollow cathodes should be avoided in practical applications because it severely degrades the overall cathode lifetime. In this study, we investigate the spot-plume transition and plasma stability characteristics of an unused segmented lanthanum hexaboride emitter. The expansion of the unstable plume mode region is observed during a discharge experiment. Subsequently, the segmented emitter is retrieved, the inner surface of the emitter is observed, and the work function on the surface is measured at room temperature. The emitter surface exhibits color variations with oxygen and carbon detection. The downstream edge shows the original purple color and almost no degradation in the work function. The high temperature in this region promotes the desorption of carbon and oxygen. In the spot mode, this region mainly contributes to thermionic electron emission; therefore, the discharge voltage in the spot mode does not change during the discharge experiment. Carbon or carbide is detected in the middle of the axial direction on the emitter surface, where the surface temperature is not sufficiently high to desorb carbon during discharge. Based on the surface analysis results, the dominant substance in the region where carbon is detected was lanthanum carbide. An increase in the work function is indicated in the region, which appears to increase the plasma instability. According to previous studies, an increase in the work function results in a rise in the potential in the emitter, and an increase in the electron temperature in the outside plume region induces the plasma instability. Further investigation is needed to understand the mechanism connecting the rise in the work function and the rise in the electron temperature in the plume region.

Dehazing, enhancing the boundaries and corners in hazed images using optimal adaptive technique

ABSTRACT Objects or images captured from the remote area will not have good quality and will not be visible because of mist, smoke, moisture and fog. Here, we rub/remove the unwanted hazes from the image using the optimal adaptive technique. An examination of the built-in boundary constraint of the transmission function is extremely valuable to our method. This constraint is handled as an optimisation problem to predict the unknown scene transmission. In addition, transmission refining techniques are used to remedy the issue based on variable splitting methodology. With only a few broad assumptions, the proposed method may recover haze-free, high-quality images having original colours and better image information. Experiment findings are done with plenty of foggy images indicating the efficiency and effectiveness of the proposed technique by using image quality parameters.

Green synthesis of silane-assisted fluorescent carbon dots based on sanding dusts and its application in flame-retardant and anti-leaching wood materials

Novel silane-assisted flame-retardant carbon dots (FR-CDs) were synthesized via the hydrothermal carbonization strategy using recycled wood sanding dusts, tris(hydroxymethyl) phosphine oxide (THPO), phosphoric acid (PA), and amino-silane as precursors. The highly transparent FR-CDs suspension appears pale yellow color under daylight and exhibits a strong fluorescence response to light excitations, which helps to keep the original color of the wood and also has broad application prospects for monitoring the leaching behavior of FR-wood. The as-prepared FR-CDs can be applied in FR-wood materials using the facile dipping process owing to their tiny nanoparticles, uniform dispersion, and numerous nitrogen–phosphorus groups. In the flame test, the FR-CDs treated wood composites emitted little smoke initially and maintained primary carbon layer that did not catch fire for over 180 s. The flame-retardancy of the FR-wood materials was confirmed by the thermo-analysis, limiting oxygen index, exposure to a high heat flux (50 kW/cm2), and the propane blowtorch tests (∼600 °C). Moreover, the formation mechanism of the silane-assisted FR-CDs during hydrothermal process and the FR-wood materials with dipping method was proposed. This study provides a facile and efficient strategy for developing highly transparent and cheap flame retardants for the wood materials, which could expand the application of the wood sanding dusts and the silane-assisted carbon-based nanomaterials in the design of anti-leaching flame-retardant materials.

Rapid color categorization revealed by frequency-tagging-based EEG

There has been much debate on whether color categories affect how we perceive color. Recent theories have put emphasis on the role of top-down influence on color perception that the original continuous color space in the visual cortex may be transformed into categorical encoding due to top-down modulation. To test the influence of color categories on color perception, we adopted an RSVP paradigm, where color stimuli were presented at a fast speed of 100 ms per stimulus and were forward and backward masked by the preceding and following stimuli. Moreover, no explicit color naming or categorization was required. In theory, backward masking with such a short interval in a passive viewing task should constrain top-down influence from higher-level brain areas. To measure any potentially subtle differences in brain response elicited by different color categories, we embedded a sensitive frequency-tagging-based EEG paradigm within the RSVP stimuli stream where the oddball color stimuli were encoded with a different frequency from the base color stimuli. We showed that EEG responses to cross-category oddball colors at the frequency where the oddball stimuli were presented was significantly larger than the responses to within-category oddball colors. Our study suggested that the visual cortex can automatically and implicitly encode color categories when color stimuli are presented rapidly.

Photochromic Responses and Stability of Functional Inks Applied on Sustainable Packaging Materials

Photochromism refers to a reversible colour change induced by the irradiation of photochromic materials with ultraviolet (UV) or visible light that reverts to the original colour after the light source is removed. This effect arises from chemical transformations between two isomers with different absorption spectra, involving processes like proton transfer, chemical-bond formation, and isomerisation. These photochromic inks, appearing as crystalline powders with micro-sized particles, require dissolution in a suitable matrix to achieve the colour change. Photochromic inks are used in security, as functional coatings for paper and packaging, in the fabric industry, and in other ways. This study examines the influence of varying concentrations of micro-sized photochromic pigments and different ink-coating thicknesses on the photochromic effect on sustainable paperboard substrates. Artificial ageing was performed to assess the photochromic response and lightfastness in relation to pigment concentration, ink-coating thickness, and the influence of the paperboard substrates. The results of this research could contribute to enhancing knowledge on employing photochromic inks for diverse packaging applications.

Comparative Study of the Expansive Behaviour of Different Internal Bleaching Agents

Internal bleaching is a conservative treatment applied to a darkened endodontically treated tooth to restore its original colour, either as a single treatment or as a treatment prior to a subsequent prosthetic phase. The aim of this study was to objectively measure and compare using an experimental model the expansive capacity of four bleaching groups: carbamide peroxide 37% (CP 37%), hydrogen peroxide 30% (HP 30%), HP 30% mixed with sodium perborate (SP) and SP mixed with distilled water. A total of 150 lower incisors (n = 30 in each group) were prepared for the Walking Bleach technique and a glass tube with oil was introduced into the coronal access cavity to measure the expansive capacity through oil displacement, due to the reaction that occurs when bleaching agents interact with dental tissues. The results after 10 days were analysed with the Games–Howell post hoc test to compare the samples. Significant higher expansion was observed with HP 30% (p < 0.05) and lower expansion with SP (p < 0.05) compared to the other groups. No significant differences were observed between CP 37% (p > 0.05) and HP 30% + SP (p > 0.05). This provides significant and observable information on the behaviour of each bleaching group and its evolution after 10 days.

A novel adaptive synchronization algorithm for a general class of fractional-order complex-valued systems with unknown parameters, and applications to circuit realization and color image encryption

This article proposes an adaptive synchronization (AS) algorithm to synchronize a general class of fractional-order complex-valued systems with completely unknown parameters, which may appear in physical and engineering problems. The analytical and theoretical concepts of the algorithm rely on the mathematical framework of the Mittag-Leffler global stability of fractional-order systems. A specific control system is established analytically based on the fractional-order adaptive laws of parameters, and the corresponding numerical results are executed to verify the accuracy of the AS algorithm. The proposed synchronization method is evaluated using the fractional-order complex Rabinovich system as an attractive example. The electronic circuits of the new system with different fractional orders are designed. By utilizing the Multisim electronic workbench software, various chaotic/hyperchaotic behaviors have been observed, and a good agreement is found between the numerical results and experimental simulation. In addition, the approximation of the transfer function for different fractional-order are presented. And the corresponding resistor and capacitor values in the chain ship model (CSM) are estimated, which can be utilized in designing electronic circuits for other fractional-order systems. Furthermore, two strategies for encrypting color images are proposed using the AS algorithm and fractional-order adaptive laws of parameters. In the first strategy, the color image is treated as a single package and divided into two vectors. The first vector is embedded into transmitter parameters, while the second vector is injected into the transmitter state signals. In the second strategy, the primary RGB channel components of the original color image are extracted and separated into two vectors, and the same process is followed as in the first strategy. These strategies complicate the decryption task for intruders. Different scales of white Gaussian noise are added to color images to examine the robustness of the proposed color images encryption strategies.

A novel “On-Off” colorimetric sensor for ascorbic acid and hydrogen peroxide based on peroxidase activity of CeO2/Co3O4 hollow nanocubes

The development of artificial nanostructured enzymes has garnered significant interest in the field of nanobiotechnology due to the distinct advantages. In this work, CeO2/Co3O4 hollow nanocubes (named as CeO2/Co3O4 HNs) with exceptional peroxidase-like activity have been prepared employing ion exchange and subsequent calcination process. In the presence of hydrogen peroxide (H2O2), the CeO2/Co3O4 HNs display high peroxidase-like activity, catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and resulting in a color change from transparent to blue. The oxidized TMB (ox-TMB) is subsequently reduced to TMB due to the reducibility of ascorbic acid (AA), restoring the original color of solution. Consequently, a straightforward and efficient "On-Off" colorimetric sensor has been established for the accurate detection of H2O2 and AA, with detection limits (LOD) of 3.56 and 0.179 μM, respectively. In summary, the prepared colorimetric sensor offers numerous advantages, including ease of operation, cost-effectiveness, rapid response, and effective visual monitoring, which holds substantial promise for applications in detection of hydrogen peroxide and ascorbic acid.

Embedding anatase, rutile, and brookite TiO2 nanoparticles to cotton fabric with epoxy silane and comparison of their effects on photodegradation

Purpose This study aims to embed anatase, rutile and brookite TiO2 nanoparticles (NPs) with different crystal phases into cotton fabrics by epoxy silane and to examine the effect of these applications on the photocatalytic and mechanical properties of the fabric. Design/methodology/approach Different aqueous dispersions which contain anatase, rutile and brookite were prepared at three different concentrations (5%, 10% and 15%). These NPs were embedded in cotton fabrics by using GPTS [(3-glycidyloxypropyl) trimethoxysilane]. Characterization tests were performed by scanning electron microscopy (SEM), Raman and Fourier-transform infrared spectroscopy (FT/IR). Samples were stained with methylene blue (MB) and then exposed to solar light for different periods. Color changes of the samples were examined with a spectrophotometer. Air permeability, abrasion and tear strength tests were applied to all samples. Findings According to SEM images, the NPs were successfully attached to the cotton fabrics, and epoxy silane coating surrounded the fiber surfaces. The presence of the coating was also confirmed by Raman spectroscopy and FT/IR. The treatments reduced the stainability of the samples. The most effective applications for ensuring photocatalytic activity in cotton fabrics were suspensions as 10% brookite, 10% anatase and 5% anatase, in descending order. The applied coating slightly reduced the samples’ air permeability, and wear and tear strength. Originality/value The importance of this study is to determine the optimal crystal phase and its concentration by using epoxy silane to ensure self-cleaning properties on cotton fabrics. The sample treated with 10% brookite is the most approached its original white color by 99.65% as a result of degradation of MB (after 120 min). On the other hand, using the pure rutile with epoxy silane was not suitable for removing MB from the fabric.

Simple preparation of PVDF composite flexible film with transparent, self-cleaning and radiative cooling properties.

Daytime radiative cooling is a technique that relies on reflecting sunlight and radiating heat through mid-infrared wavelengths to cool objects. However, most daytime radiative cooling materials are not transparent, cannot be used for vehicle windows or other objects that need to retain their original color, and are susceptible to rain, dust, and other contamination, resulting in reduced cooling performance. Here, we developed a transparent, self-cleaning, radiative cooling, highly flexible PVDF composite film (PPF film), which was prepared by solvent evaporation phase conversion method and scraping coating method. The preparation method is simple and the material is easy to obtain. The obtained PPF film can be crimped to different degrees, has high flexibility, a transmittance of 94% in the visible light range (380-760 nm), and a water contact angle of 105° and above, and has self-cleaning performance. In the range of 8-13 μm, the average emissivity of the film reached 94.42%. Outdoor experiments show that, on sunny days, the cavity temperature of the device coated with PPF film glass decreases by 5-6 °C compared with that of bare glass, indicating that the PPF film has excellent radiative cooling performance. In addition, it has relatively strong mechanical properties, ultraviolet aging resistance and acid and alkali resistance. The design of the PPF film enables the radiative cooling material to be transparent, self-cleaning and flexible, with broad application prospects in the outer surface of objects requiring light transmission and cooling, such as special-shaped curved surfaces, solar panels, and architectural glass.

Separating Shading and Reflectance From Cartoon Illustrations.

Shading plays an important role in cartoon drawings to present the 3D lighting and depth information in a 2D image to improve the visual information and pleasantness. But it also introduces apparent challenges in analyzing and processing the cartoon drawings for different computer graphics and vision applications, such as segmentation, depth estimation, and relighting. Extensive research has been made in removing or separating the shading information to facilitate these applications. Unfortunately, the existing researches only focused on natural images, which are natively different from cartoons since the shading in natural images is physically correct and can be modeled based on physical priors. However, shading in cartoons is manually created by artists, which may be imprecise, abstract, and stylized. This makes it extremely difficult to model the shading in cartoon drawings. Without modeling the shading prior, in the paper, we propose a learning-based solution to separate the shading from the original colors using a two-branch system consisting of two subnetworks. To the best of our knowledge, our method is the first attempt in separating shading information from cartoon drawings. Our method significantly outperforms the methods tailored for natural images. Extensive evaluations have been performed with convincing results in all cases.

Biodiversity of freshwater fish in Pangalengan District, Bandung, West Java

Java Island has about 132 freshwater fish species compared to the other major islands in the Sundaland region, such as Sumatra, which has about 589 species. This study aims to reveal and identify the diversity of freshwater fish around Pulosari Village, Pangalengan District. Exploration activities were conducted in river and lake habitats of Pangalengan District, Bandung Regency, West Java. Specimens were collected by authors and local fishermen using three fishing gears: gill nets, fishing rods, and fish scrappers. Immediately after collecting, fish were documented using a digital camera to obtain their original color. In this study, a total of 11 freshwater fish species belonging to 10 families were found. Some species are recognized as introduced fish.

Mechanism underlying ultraviolet-irradiation-induced discoloration of dental zirconia ceramics stabilized with 3 and 5 mol% yttria

The present study aimed to analyze the mechanism underlying the color alteration of dental zirconia ceramics stabilized with 3 and 5 mol% yttria (3YZ and 5YZ, respectively) caused by 254-nm ultraviolet (UV) irradiation. Fully sintered specimens of 3YZ (Zpex, Tosoh) and 5YZ (Zpex Smile, Tosoh) were irradiated with 254-nm UV at 4 mW/cm2 (up to 60 min). Color alteration (ΔE) was analyzed using the CIE L*a*b* colorimetric system. The UV-induced excitation of oxygen vacancies, which capture two electrons in zirconia (i.e., F center) was analyzed using photoluminescence (PL) and electron spin resonance (ESR) spectroscopy. Furthermore, the spontaneous change in ΔE after cessation of UV irradiation was evaluated. UV irradiation increased ΔE to 13.4 in 3YZ and 10.3 in 5YZ within the initial 10 min of irradiation, and then, ΔE reached a plateau. A PL peak was observed at 435 nm, which decreased with UV irradiation. In addition, UV irradiation generated an ESR signal attributed to the F+ centers formed via one-electron detachment from F centers. The signal intensities of both 3YZ and 5YZ increased with irradiation time; however, the signal intensity was higher in 3YZ than that in 5YZ. After cessation of UV irradiation, ΔE gradually decreased to approximately 2, which took a few weeks. The discoloration of 3YZ and 5YZ caused by UV irradiation was due to the excitation of F centers. Although the specimens spontaneously reverted to their original color over time, clinical procedures involving UV irradiation, such as photo-functionalization, should be performed with caution to avoid damaging the esthetics of dental zirconia restorations.

Reattachment of Fractured Maxillary Central Incisor with Fibre Post

Abstract Traumatic dental injuries leave dental practitioners with severe therapeutic problems. Traumatic dental injuries with a prevalence of 25% among school children and 33% among adults are a public health problem that can have a negative influence on the quality of life. In cases of trauma to the facial region, the incidence of maxillary central incisors is 37%, followed by that of lateral incisors (16%). Traumatic injuries to teeth can be uncomplicated crown or crown-root fractures or complicated crown or crown-root fractures. Various treatment options may be employed for the management of complicated crown-root fractures of teeth. The reattachment of tooth fragments has been a preferable alternative to the restoration of the tooth. Reattachment provides a better aesthetic result in less time, i.e. regarding the original tooth shape colour texture translucency and occlusal contacts which is both very satisfying for the patient as well as the practitioner. The purpose of this case report is to evaluate the long-term prognosis of a maxillary central incisor with complicated crown-root fracture managed by reattachment of the fragment with fibre post.

Evaluating the Color Matching Ability of a Smart Chromatic Technology-Based Composite Resin for Premolar Teeth Restoration.

Objectives: This study aims to evaluate the color-matching ability of OMNICHROMA composite, a single-shade composite, using the CIE L ∗ a ∗ b ∗ system and determining ΔE values. Materials and Methods: In this in vitro study, 30 intact premolar teeth were collected, cleaned, and disinfected with 0.5% thymol solution. The teeth were stored in distilled water at 37°C. A putty index calibrated the color assessment sites on buccal and lingual surfaces. Two cavities were prepared, one with 1.25 mm depth (enamel) and another with 2.25 mm depth (dentin), and restored using OMNICHROMA composite resin. The putty index measured the color of the cured composite, and ΔE between the composite and original tooth color was calculated. Statistical analysis: Data analysis included t-tests, correlation coefficients, and Fisher's exact test (α = 0.05). Results: The mean ΔE was 2.39 in enamel cavities and 2.32 in dentin cavities, both within the clinically acceptable range (<3.3). In enamel cavities, the composite color was darker than the tooth, shifting toward green and blue shades. In dentin cavities, the composite color was lighter than the tooth, with shifts toward green and yellow shades. Color matching was slightly better in dentin cavities, but the difference was not statistically significant (p=0.719). Conclusion: OMNICHROMA composite resin's color matching falls within the clinically acceptable range, unaffected by cavity depth.

Multi-color-image compression-encryption scheme in the quaternion discrete Fresnel domain

A multiple color images compression-encryption scheme is designed with compressive sensing in the quaternion discrete Fresnel transform. To tackle multiple color images in a holistic manner, the discrete Fresnel transform is extended into the quaternion domain and the images are encrypted with the quaternion discrete Fresnel transform. In this scheme, the RGB color components of plaintext images are simultaneously compressed and encrypted in three mutually independent channels. Then the red, green and blue components are scrambled respectively by a chaos sequence generated by the 2D logistic-sine-coupling map. Each color component matrix is compressed with sparse representation and matrix measurement. Subsequently, the compressed matrices are integrated into the quaternion algebras and re-encrypted by the defined quaternion discrete Fresnel transform. The devised nonlinear cryptosystem originates from the asymmetric phase truncation operation. In decryption, the original color images are reconstructed by the gradient descent with a sparsification algorithm. The proposed multiple color images compression-encryption algorithm is feasible, effective, secure and robust.