Color Stability Research Articles

Evaluation of the Thermal and Light Stability of β-Carotene Extracted from Mauritia flexuosa Using Ionic Liquid

The growing concern over the adverse effects of synthetic dyes has generated interest in the use of natural pigments by the food industry. β-carotene, a carotenoid found in various plant sources, is recognized for its antioxidant properties and provitamin A activity. The fruit of the buriti palm (Mauritia flexuosa), which is particularly rich in β-carotene, serves as a significant natural source of this pigment. This study aimed to extract β-carotene from buriti fruit using ionic liquids as an alternative to conventional organic solvents like acetone. β-carotene content was determined by HPLC and showed that extraction with [C4mim] [BF4] not only improved β-carotene extraction efficiency compared to acetone (19.21 and 13.13 mg/100 g, respectively) but also provided greater pigment stability during light, thermal and color stability tests. Moreover, ionic liquids are aligned with the principles of green chemistry and offer a sustainable and safe alternative for the food industry. Its favorable characteristics not only reduce environmental impacts associated with conventional solvents, but also ensure an increase in the shelf life of natural dyes, thus promoting the safety and quality of food products.

Indirect Composite Color Stability And Surface Roughness After Finishing

Indirect Composite Color Stability And Surface Roughness After Finishing

Polysaccharide modified fish gelatin intelligent hydrogels for reliable monitoring freshness of shrimp (Litopenaeus vannamei)

This study utilized κ-carrageenan (κC), konjac glucomannan (KGM), and xanthan gum (XG) to develop fish gelatin-anthocyanin intelligent hydrogels. The gelation properties, structural characteristic of hydrogels in monitoring shrimps (Litopenaeus vannamei) freshness were explored. The results showed that the addition of polysaccharides to fish gelatin (FG) notably enhanced gelation properties and color stability. During storage of shrimp at 4 °C, the intelligent hydrogels exhibited a progressive color change from transparent to brown. This color change demonstrated a strong linear relationships with total viable counts (TVC) and a significant nonlinear correlations with total volatile basic nitrogen (TVB-N) levels, indicating the intelligent hydrogels’ high reliability and potential for practical application. This approach offers a novel method for assessing and monitoring the quality of fresh aquatic products.

Azo Coupling Reaction for Spectrophotometric Determination of Sulfanilamide Using β -Naphthol as a Reagent

This research is based on one simple and good method for determining sulfanilamide in its pure state and in pharmaceutical preparations. Spectrophotometric determination of Sulfanilamide using the azo coupling reaction in an aqueous solution and several standard solutions were prepared. The optimal conditions were also studied. The effects of the type of acid and its volume, the influence of the base type and its volume, the effect of reagent volume (100 µg/ml), the effect of reaction time on the color stability of the product, the effect of adding sequence, the solvent effect, and the effect of temperature on the formation and stability of the colored product. The product for the Sulfanilamide drug is auburn at a wavelength of 489 nm; the method obeyed Beer's law in a range of concentrations ranging from 1–12 µg/ml; and the molar absorptivity was 28840.76 L/mol.cm. Sandal's sensitivity (0.00091 μg/cm), detection limit (0.2472 µg/ml), correlation coefficient value 0.9984, and RSD% value 0.01365, By applying the method to a pharmaceutical preparation containing Sulfanilamide, the recovery value ranged between 102.1306%.

THE EFFECT OF DIFFERENT STAINING SOLUTIONS ON THE COLOR STABILITY OF PERMANENT INDIRECT COMPOSITE RESINS PRODUCED BY ADDITIVE AND SUBTRACTIVE TECHNIQUES

Objective: To investigate the effects of various beverages on the color stability of permanent composite resins produced by additive (AM) or subtractive manufacturing (SM) techniques comparatively. Materials and Methods: Six composite resin materials produced by SM (Vita Enamic-VE, Cerasmart-CE, Lava Ultimate-LU) and AM (Varseo Smile Crown plus-VSC, Saremco print Crowntech-SPC, Formlabs 3B Permanent Crown-FPC) techniques were selected and soaked in different solutions (artificial saliva, black tea, coffee) for different times (0, 1 and 7 days). L*, a*, b* values of the samples were recorded using a spectrophotometer. The color changes of the samples were determined using the CIELAB formula. In determining the color differences between the test materials, Kruskal-Wallis analysis was used when one-way analysis of variance wasn’t available. Results: Group VE was the least stained group on the 1st and 7th day of artificial saliva solution and the 7th day of coffee solution, while Group CE was the least stained group on the 1st day of coffee solution. In the tea solution, on the 1st and 7th days, there wasn’t difference in the materials' color change (p>0.05). Tea and coffee solutions caused statistically significantly more color change in all test materials than artificial saliva (except Group CE on the 7th day, Group VSC and FPC on the 1st day) (p<0.05). Conclusion: 3D permanent composite resins generally showed more staining than CAD/CAM milled composite resins. Tea and coffee staining solutions changed the color of the materials compared to artificial saliva. As the storage time increased, more color changes were observed.

Comparative Evaluation of the Shear Bond Strength and Color Stability of Two Commercially Available Intraoral Porcelain Repair Systems: An In Vitro Study

Comparative Evaluation of the Shear Bond Strength and Color Stability of Two Commercially Available Intraoral Porcelain Repair Systems: An In Vitro Study

Color Stability of Different Restorative Approaches for the Masking of Silver Diamine Fluoride after Thermal Aging

Color Stability of Different Restorative Approaches for the Masking of Silver Diamine Fluoride after Thermal Aging

Evaluating the clinical significance of color stability in nanohybrid composite resins: a comparative study of local and international brands

Aims: The objective of this study was to evaluate the color stability of five nanohybrid composite resins, including locally produced Turkish brands and an international brand, after exposure to staining and brushing simulations over time. Methods: Five nanohybrid composite resins; Filtek Z550 (FLT), Dolgunn (DLG), RubyComp Nano (CMP), Nova Compo C (NVC), and Parion (PRN) were tested. Specimens underwent staining and brushing simulations designed to replicate clinical oral conditions. The staining process involved immersing the specimens in a coffee solution for 8 hours per day over a 10-day period to simulate short-term staining (t1), and for 12 days to simulate long-term staining equivalent to 1 year (t2). Brushing cycles were used to replicate the mechanical wear caused by daily oral hygiene practices. Color measurements were recorded at baseline (t0), after 10 days of staining (t1), and after 1 year of simulated staining and brushing (t2). Additional analyses were conducted using Energy-dispersive X-ray spectroscopy (EDX) and Scanning Electron Microscopy (SEM) to investigate structural and surface characteristics. Statistical analysis was performed using generalized linear models and two-way robust ANOVA to assess the significance of differences in color stability, with a significance level set at p

L-lysine enhances pork color through antioxidant activity and myoglobin conformational changes

This study aimed to investigate the effect of L-lysine (Lys) on the color of pork and reveal the possible mechanism. The results showed that the L* and a* values increased from 53.69 to 56.32, 56.39, and 56.47, and from 12.93 to 13.21, 13.24, and 13.52 with the addition of 0.1 %, 0.15 % and 0.2 % Lys, respectively. Meanwhile, the oxymyoglobin (Fe2+) levels increased from 21.14 % to 22.63 %, 23.83 %, and 23.53 %, while the metmyoglobin (Fe3+) levels decreased from 44.69 % to 40.28 %, 41.21 %, and 41.63 % with the addition of 0.1 %, 0.15 % and 0.2 % Lys, respectively. Additionally, the addition of Lys increased total sulfhydryl and active sulfhydryl contents, and decreased the levels of reactive oxygen species (ROS) (P<0.05). The particle size and the absolute value of the ζ-potential increased with the addition of Lys, reaching maximum values of 534.39 nm and −13.73 mV, respectively. The molecular dynamics results suggested that Lys can bind to myoglobin (Mb) through hydrophobic interactions and hydrogen bonds, forming a stable Lys-Mb complex, acting as a protective shield to prevent the entry of ROS and other oxidizing agents. Finally, the addition of 0.15 % Lys resulted in the highest surface hydrophobicity, which was 5.79 μg. The multispectral results indicated that Lys primarily induces changes in the secondary and tertiary structures of Mb through interactions with tyrosine residues. These changes stabilized the free-moving rings within the amino acid residues of Mb, thereby improving the structural stability of Mb and ultimately enhancing the color stability of pork. In summary, Lys improved meat color stability through a dual mechanism of antioxidation and interaction with Mb to alter its conformational stability.

Effect of aging on dimensional accuracy and color stability of CAD-CAM milled and 3D-printed denture base resins: a comparative in-vitro study

BackgroundThere is a lack of studies comparing the dimensional accuracy and color stability of denture base resins made using computer-aided design and computer-aided manufacturing (CAD-CAM) milling, 3-dimensional (3D) printing, and conventional denture processing techniques. This makes it challenging to determine the best method to fabricate complete dentures. The objective of this in vitro investigation was to assess and contrast the color stability and dimensional accuracy of denture base resins that were 3D printed and CAD-CAM milled, both before and after aging by thermocycling using digital surface matching technology and a benchtop laser scanner without using a spray, to optimize adaptation of the denture base and cast to minimize any imperfections and to evaluate the impact of the denture cleansing solution on the stability of color.MethodsEvaluation of the dimensional accuracy (n = 27) was completed on a sectional maxillary stone cast using a digital 3D-surface matching software before and after 5000 thermocycles. A spectrophotometer was used to measure the color change (△E00) of all disc specimens (N = 54) before and after 500 thermocycles and immersion in denture cleansing solution for 30 cycles (3 min each) daily for 6 days. The Kruskal Wallis test, Dunn’s post hoc test, Tukey’s test with Bonferroni adjustment, one sample t test and independent t test were used to statistically analyze the data (α < 0.05).ResultsThermocycling decreased the dimensional accuracy of the heat polymerized group at all 5 locations and the 3D-printed group at locations 1, 3 and 5 (P > .05), while it had no significant difference on the CAD-CAM milled group at all locations (P < .05). The color change (△E00) was lowest in the CAD-CAM milled group, moderate in the heat-polymerized group and highest in the 3D-printed group. After immersion in denture cleanser, the color change (△E00) was significantly higher in the 3 groups compared with after thermocycling (P > .001).ConclusionsCAD-CAM milled resins had the highest dimensional accuracy and the best color stability, conventional heat polymerized acrylic resins showed moderate change in dimensional accuracy and color stability, while the 3D- printed resin had the lowest dimensional accuracy and color stability after aging by thermocycling.

DESIGN OF FOODGRADE OLEOFOAMS FROM CARNAUBA WAX AND GLYCERYL MONOSTEARATE WHIPPABLE OLEOGELS

The study aimed to design oleofoams based on carnauba wax (CW) and glyceryl monostearate (GMS), investigating the effect of their ratio (10:0, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8; 0:10) on the resulting oleofoam properties. Dynamic rheological analyses were performed to explore the mechanical properties of both oleogels and oleofoams. Oleofoams were also characterized for texture, color and physical stability Both oleogels and oleofoams exhibited a solid-like behaviour confirming the formation of a fat crystal network during the cooling and whipping process. Oleogels with lower G' values generated the most stable oleofoams. CW-based oleogel did not whip, while GMS-based oleofoam did not show desirable properties. . A CW: GMS ratio of 3:7, 4:6, or 5:5 is required to obtain self-standing oleogels with high oil binding capacity, whippable in 25-40 minutes reaching an overrun of 50%. The resulting oleofoams are stable and characterized by high network strength, crucial for food applications.

Preparation of Multi-colored Binary Silica Supraballs and Color Fine-tuning Based on Color Mixing

Structural colors are highly valued for their eco-friendliness and long-term color stability, deriving from the interaction of structural units with incident light. However, traditional methods for adjusting structural colors typically involve altering the size of structural units, a labor-intensive process necessitating specific diameters for each desired color. Moreover, colors exhibited by photonic crystal materials are monochromatic colors with a narrow wavelength range, failing to exhibit polychromatic colors. This restricts their practical applications, as they do not accurately represent the actual color of objects themselves. Hence, this study focuses on fabricating binary supraballs can display polychromatic colors. These supraballs consist of two types of structural units with distinct diameter differences. By adjusting the mass ratio between these units within the supraballs, fine color tuning is achievable. Utilizing three different diameters of silica nanospheres, this method enables the fabrication of supraballs with a diverse range of colors spanning nearly the entire visible spectrum. The adjustable colors of these binary supraballs not only enhance their ability to replicate the colors of objects, but also reduce the significant workload involved in preparing the original structural units. The synthesized supraballs are in powder form, directly applicable as coatings, inks, and other materials.

Determination of Cortisol Hormone from Sweat Samples and Interpretation with Microcontroller

Cortisol, known as the body's stress hormone, regulates metabolism, inflammation, and the immune system. It affects various bodily systems such as the nervous, immune, cardiovascular, respiratory, reproductive, and musculoskeletal systems. Normal sweat cortisol levels range from 8 to 142 ng/ml, with elevated levels indicating stress (200 ng/ml in women, 500 ng/ml in men). This study focuses on colorimetric cortisol analysis using a microfluidic layer to collect sweat samples. Samples are mixed with a specific color reagent. Cortisol levels are quantitatively analyzed using Z-Score values and RGB channel density via photographs taken with the ESP 32 module. The aim is to determine cortisol levels, aiding in diagnosing conditions like Cushing's syndrome and Addison's Disease, leveraging wearable technology. The developed system integrates a microcontroller into the wearable microfluidic system for cortisol measurements throughout the day. Data is displayed and recorded on a computer for streamlined cortisol monitoring. The blue tetrazolium method used offers stable colors and rapid reactions (10 minutes). The Limit of Detection (LOD) is 0.3 ug/mL, with a detection limit of 1.1 ug/mL. Combined with the ESP 32 Cam module, the system detects cortisol concentrations from 0.8 – 60 ug/mL.

Enhanced mechanical, thermal, water and UV aging resistance properties of bamboo fiber/HDPE composites through silane coupling agent modified nano-SiO2-TiO2

Nano-TiO2 is widely employed to enhance the properties of plant fiber reinforced thermoplastic polymer composites due to its chemical inertness, anti-aging, and anti-bacterial properties. However, the enhancement of bamboo fiber/high-density polyethylene (BF/HDPE) composites is limited by the high photocatalytic activity of nano-TiO2 and its poor compatibility with the BF/HDPE matrix. This study employs an organic-inorganic co-modification to prepare BF/HDPE composites reinforced with silane coupling agent KH550 modified nano-SiO2 coated nano-TiO2 (KH550/SiO2-TiO2) by spray coating and melt mixing methods, and the properties of the composites were tested and characterized. The effects of KH550 and KH550/SiO2-TiO2 content on the properties of modified BF/HDPE composites, including mechanical properties, water absorption, thickness swelling rate, water contact angle, thermal stability, and UV aging resistance，which were characterized using methods of mechanical tests, FTIR, UV-Vis, XPS and SEM, both before and after modification. The results indicate that KH550 effectively improves the agglomeration phenomenon and enhances the dispersibility of nano-SiO2-TiO2 in the BF/HDPE composites. The optimal thermal stability is achieved when the BF/HDPE composites modified with a 5 wt% KH550/SiO2-TiO2, while BF/HDPE composites modified with a 3 wt% KH550/SiO2-TiO2 exhibit the better mechanical properties, water resistance, and UV aging resistance compared to other contents. Flexural strength and modulus of KH550/SiO2-TiO2 modified BF/HDPE composites increased by 18.71 % and 17.92 %, tensile strength and modulus increased by 7.74 % and 21.92 %, respectively. The 480-hour water absorption and thickness swelling rate decreased by 18.68 % and 20.73 %, respectively, and the contact angle increased by 19.17°; better thermal stability and color stability was observed. The spray coating method was more effective in improving the properties of the modified BF/HDPE composites than the melt mixing method. Comprehensive analysis indicates that the mechanical properties, water resistance, thermal stability, and UV aging resistance of the BF/HDPE composites reinforced with 3 wt% KH550/SiO2-TiO2 prepared by the spray coating method are significantly enhanced.

Comparison of the Characteristics of Baekak(chalk) and Hobun(shell) Pigment for Dancheong based on Natural Raw Materials

Calcium carbonate white pigments were manufactured by classifying them into Baekak(chalk) and Hobun(Shell) according to the type of natural raw material, and their material characteristics were analyzed. Their performances were compared by evaluating their weather resistance, antifungal activity, and flame retardancy. The main components of Baekak pigments are calcite and dolomite, and those of Hobun pigments a re calcite and a ragonite. Depending on the raw material, the specific factors identified are Mg from the mineral composition of Baekak pigments, and P and S from the protein composition of Hobun pigments. The particle shape of the pigment shows a crystal structure unique to minerals in the case of Baekak pigments, but the Hobun pigments are classified into plate-shaped or columnar structures depending on the raw material and are in an aggregated state with a large specific surface area. While the absorption amount of Baekak pigments made from limestone and dolomite is similar, that of Hobun pigments shows differences depending on the raw material, with the absorption amount being high in the order of oyster &gt; cockle &gt; clam. As a result of the color analysis, both the Baekak and the Hobun pigments had L* values of over 90 and opacity of over 90, indicating good whiteness and painting workability. As a result of the accelerated weathering test, the final color difference value(ΔE) was less than 2.02, which was difficult to recognize with the naked eye, and the Hobun pigment showed superior color and film stability compared to the Baekak pigment. As a result of the antifungal test, all calcium carbonate-based white pigments showed high preventive effects against decay fungi, and among them, the pigment made from clams and cockles showed excellent antiseptic properties. In addition, the pigment made from clams and cockles has been shown to have flame retardant properties, and it is expected that it will contribute to enhancing the preservation of organic cultural heritage when applied to it.

Effects of different beverages on the color stability and fluorescence of resin composites: in situ study.

To evaluate the color change (ΔE) and fluorescence (FL) of resin composites after the consumption of beverages. One hundred and sixty disc-shaped specimens (6 × 2mm) of Filtek Z350 XT (FZX) and Forma (FOR) resin composites were randomized for use in devices by five volunteers who ingested 100ml daily of red wine (RW), beer (BE), energy drink (ED) and water (WT) over 15 days. The data were collected from digital photographs and analyzed using the CIE-Lab and RGB scales to obtain ΔE and FL and statistics via two-way ANOVA (for ΔE) and ANOVA for repeated measures (for FL), α = 0.05. The highest ΔE values were obtained for FZX and FOR in the RW (ΔE = 10.5 for FZX and ΔE = 9.90 for FOR) and BE (ΔE = 6.3 for FZX and ΔE = 6.1 for FOR) drinks. For FL, there were different levels of change between the composites, with a much more significant reduction in FL intensity with RW. Beverages have the potential to stain the composites evaluated, especially alcoholic beverages. Before carrying out an esthetic treatment with resin composites, it is ideal to investigate the types of drinks consumed by patients, for greater predictability of treatment.

Pulsed Light Treatment Effect on Color, Oxidative Stability, and Listeria monocytogenes Population of Sliced Mortadella.

This study evaluated the effects of high-intensity pulsed light (PL) on sliced mortadella, assessing how the parameters pulse width (1260 to 2520 µs) and number of pulses (one to three) influence color, oxidative stability, and Listeria monocytogenes population. The different PL parameters generated a fluence ranging from 2.64 to 6.57 J/cm2 and irradiance ranging from 1046.9 to 1738.8 W/cm2. The PL slightly increased the temperature and pH of the samples, and this elevation was well correlated to the higher number of pulses and higher fluence. The color parameter a* was reduced while b* values increased after PL application, with these effects being more significant in treatments with a higher number of pulses and higher fluence. The highest values of TBARS were found in treatments with higher fluence (5.28 and 6.57 J/cm2), which were characterized by the attribute "oxidized color" in sensory evaluation. The different PL conditions reduced the count of L. monocytogenes by up to 1.44 Log CFU/cm2. The treatment with a pulse width of 1260 µs, two pulses, fluence of 4.38 J/cm2, and irradiance of 1738.3 W/cm2 achieved the same efficacy in pathogen reduction as the treatments with higher fluence. Moreover, these PL conditions had a minimal impact on the color and oxidative stability of mortadella, demonstrating an effective balance between microbiological safety and quality preservation.

Assessing the Aesthetic Performance of CAD/CAM Provisional Restorative Materials: A Spectrophotometric Analysis.

Achieving color match between natural teeth and restorative materials is crucial in dentistry. Factors such as the light source, brightness, and opacity influence tooth color, determined by light absorption and scattering within the material. Advances in CAD/CAM systems have enhanced prosthodontic treatments, particularly with new temporary materials, but data on their color stability and masking ability remains limited. However, data on the color stability and masking ability of these CAD/CAM materials is limited. Telio® CAD-Temp and VITA CAD-Temp® blocks were cut into slices and polished. Composite resin specimens were prepared using a custom-designed metal resin former and light-cured. Samples were paired randomly and assigned to experimental groups based on base type and thickness (n = 30). Samples were stored in a controlled environment for 24 h before color evaluation using an EasyShade® V spectrophotometer. Color difference (ΔE) was calculated using L*, a*, and b* values. Statistical analyses included the Shapiro-Wilk test, Levene's test, and three-way ANOVA, with post-hoc comparisons using the Bonferroni method (α = 0.05). ΔE was classified according to perceptibility (PT = 1.2) and acceptability (AT = 2.7) values.

The effectiveness of direct versus indirect restoration techniques following canal therapy

The restoration of endodontically treated teeth is a critical aspect of dental practice, with the choice between direct and indirect restoration techniques being central to optimizing clinical outcomes. Direct restorations, such as composite resins, offer advantages in terms of cost, time efficiency, and preservation of tooth structure. However, their long-term performance, particularly in posterior teeth, may be compromised by issues such as marginal leakage, wear, and discoloration. Indirect restorations, including crowns, onlays, and inlays, provide enhanced durability, fracture resistance, and aesthetic outcomes, particularly for teeth that have undergone significant structural loss. These restorations, often made from ceramics or metals, offer superior longevity but come with higher costs and longer treatment times. The aesthetic performance of restorations plays a significant role in patient satisfaction. While direct restorations allow for immediate aesthetic adjustments and are generally more affordable, they may suffer from discoloration and wear over time. Indirect restorations, particularly porcelain-based options, offer better color stability and natural appearance, making them a preferred choice for patients with high aesthetic demands. Cost-effectiveness is another critical factor influencing clinical decision-making. While direct restorations are more affordable initially, their long-term cost-effectiveness may be compromised by the need for repairs or replacements. Indirect restorations, despite their higher upfront cost, often prove to be more economical in the long run due to their durability and reduced need for maintenance. The decision between direct and indirect restoration techniques should be individualized, considering factors such as tooth location, the extent of damage, aesthetic requirements, and financial constraints. A comprehensive evaluation of these factors, along with clear communication with the patient, is essential for achieving optimal clinical outcomes. Indirect restorations generally offer better long-term performance, particularly for heavily compromised teeth, while direct restorations remain a viable option for cases where cost and time efficiency are prioritized.

Lattice reconstruction for mixed-halide blue perovskite light-emitting diodes with high brightness, outstanding color stability and low efficiency roll-off

We report a simple, effective, and universal lattice reconstruction approach to improve the quality of perovskite films by using nonpolar solvents with high Gutmann donor numbers (DNs). We find that high-DN nonpolar solvents, for instance, ethyl acetate, can interact with perovskite precursors. Such a solvent can make the perovskite lattice more ordered and “harder” and promote the formation of heterostructures with low-dimensional perovskite impurities and residual solvent molecules. As a result, the lattice-reconstructed perovskite films exhibit reduced defect densities and suppressed ion migration. The resultant mixed-halide blue perovskite light-emitting diodes (PeLEDs) show greatly enhanced tolerance to high driving current densities and voltages, demonstrating high brightness, outstanding color stability and low efficiency roll-off. Our work provides a deep understanding of the interactions between nonpolar solvents and perovskites and offers useful guidelines for further development of high-power PeLEDs.