Search Results (940)

Fresh meat and fish are widely consumed foods with short and very short shelf lives, respectively. Efficient supply chains and the judicious use of food packaging are the most effective means of extending shelf life and thus reducing food waste and improving food safety. Food packaging that allows for the use of a modified atmosphere (MAP) is effective in extending the period where the food is both palatable and safe. However, monitoring the state of aging and the onset of spoilage of the product poses challenges. Microbial counts, pH measurements, and sensory evaluations are all informative but destructive and are therefore only useful for monitoring quality via sampling. More attractive would be a technology that can follow the progress of ageing in an individual product while leaving the food packaging intact. Here, we present a pH indicator to be placed inside each package that may be read by the naked eye. It is a colorimetric indicator with a matrix made of pure amylose (AM; 99% linear α-glucans) and cellulose nanofibers (CNFs). Suitable mechanical properties of films cast of the two polysaccharides were achieved via the optimization of the blending ratio. The films were loaded with either of two pH indicators: anthocyanin extracts from red cabbage (RCA) and the synthetic dye neutral red (NR). Mechanical, thermal, permeability, microstructural, and physical properties were tested for all composite films. Films with 35% CNF (35AC-RCA) and (35AC-NR) were selected for further study. Minced meat was packaged under MAP conditions (70% O₂ + 30% CO₂), while minced fish was packaged under MAP (70% N₂ + 30% CO₂) and stored at 5 °C for 20 days. Microbial growth, pH, and sensory scores of the minced meat systems differentiated between fresh (0–6 days) and medium-fresh (7–10 days), and minced fish between fresh (0–10 days) and medium-fresh (11–20 days). The total color difference showed that the RCA indicator was able to differentiate between fresh (red) and medium-fresh (pink-red) minced meat, while for minced fish, this indicator discriminated between three stages: fresh (red), medium-fresh (pink-red), and spoiled (pink-blue). The NR indicator failed to discriminate the freshness of either meat or fish under the effect of MAP. Pearson correlation statistical models showed a correlation between color change of the indicator, pH, content of gases, and gas content. In summary, RCA immobilized in an AM + 35% CNF nanocomposite film can monitor the freshness of packaged minced meat/fish under the effect of MAP via color change that may be evaluated with the naked eye. Full article

The development of novel cathodic materials with tailored nanostructures is crucial for the advancement of electrochromic devices. In this study, we synthesized cobalt-doped titanium dioxide (Ti-Co) thin films using a facile hydrothermal method to investigate the effects of cobalt doping on their structural, morphological, and electrochromic properties. Comprehensive characterization techniques, including X-ray diffraction and Raman analysis, confirmed the highly crystalline nature of the Ti-Co thin films, with specific Raman bands indicating distinct modifications due to cobalt incorporation. The TiO₂ nanorods, optimally doped with cobalt (TC-3), demonstrated enhanced charge transport and mobility, significantly improving the electrochromic performance. Among the various compositions studied, the TC-3 sample exhibited superior lithium-ion accommodation, achieving an optical modulation of 73.6% and a high coloration efficiency of 81.50 cm²/C. It also demonstrated excellent electrochromic stability, maintaining performance for up to 5000 s of coloring/bleaching cycles. These results confirm the beneficial impact of cobalt doping on the structural and functional properties of the host material. Furthermore, the practical effectiveness of the TC-3 thin film was validated through the fabrication of an electrochromic device, which showed efficient coloration and bleaching capabilities. This comprehensive research enhances the understanding and functionality of Ti-Co nanorod architectures, highlighting their promising potential for advanced electrochromic applications. Full article

Anthocyanins are amazing plant-derived colorants with highly valuable properties; however, their chemical and color instability issues limit their wide application in different food industry-related products such as active and intelligent packaging. In a previous study, it was demonstrated that anthocyanins could be stabilized into green plasticizers namely deep eutectic solvents (DESs). In this work, the fabrication of edible films by integrating anthocyanins along with DESs into biocompatible chitosan (CHT)-based formulations enriched with polyvinyl alcohol (PVA) and PVA nanoparticles was investigated. CHT/PVA-DES films’ physical properties were characterized by scanning electron microscopy, water vapor permeability, swelling index, moisture sorption isotherm, and thermogravimetry analysis. Innovative red-to-blue formulation films were achieved for CHT/PVA nanoparticles (for 5 min of sonication) at a molar ratio 1:1, and with 10% of ternary DES (TDES)-containing malvidin-3-glucoside (0.1%) where the physical properties of films were enhanced. After immersion in solutions at different pH values, films submitted to pHs 5–8 were revealed to be more color stable and resistant with time than at acidic pH values. Full article

Inorganic CsPbX₃ (X = Cl, Br, I) perovskite quantum dots (PQDs) have attracted widespread attention due to their excellent optical properties and extensive application prospects. However, their inherent structural instability significantly hinders their practical application despite their outstanding optical performance. To enhance stability, an in situ electrospinning strategy was used to synthesize CsPbX₃/polyacrylonitrile composite nanofibers. By optimizing process parameters (e.g., halide ratio, electrospinning voltage, and heat treatment temperature), all-inorganic CsPbX₃ PQDs have been successfully grown in a polyacrylonitrile (PAN) matrix. During the electrospinning process, the rapid solidification of electrospun fibers not only effectively constrained the formation of large-sized PQDs but also provided effective physical protection for PQDs, resulting in the improvement in the water stability of PQDs by minimizing external environmental interference. Even after storage in water for over 100 days, the PQDs maintained approximately 93.5% of their photoluminescence intensity. Through the adjustment of halogen elements, the as-obtained composite nanofibers exhibited color-tunable luminescence in the visible light region, and based on this, a series of multicolor anti-counterfeiting patterns were fabricated. Additionally, benefiting from the excellent water stability and optical performance, the CsPbBr₃/PAN composite film was combined with red-emitting K₂SiF₆:Mn⁴⁺ (KSF) on a blue LED (460 nm), producing a stable and efficient WLED device with a color temperature of around 6000 K and CIE coordinates of (0.318, 0.322). These results provide a general approach to synthesizing PQDs/polymer nanocomposites with excellent water stability and multicolor emission, thereby promoting their practical applications in multifunctional optoelectronic devices and advanced anti-counterfeiting. Full article

Responsive photonic crystal hydrogel sensors are renowned for their colorimetric sensing ability and can be utilized in many fields such as medical diagnosis, environmental detection, food safety, and industrial production. Previously, our group invented responsive photonic nanochains (RPNCs), which improve the response speed of photonic crystal hydrogel sensors by at least 2 to 3 orders of magnitude. However, RPNCs are dispersed in a liquid medium, which needs a magnetic field to orient them for the generation of structural colors. In addition, during repeated use, the process of cleaning and redispersing can cause entanglement, breakage, and a loss of RPNCs, resulting in poor stability. Moreover, when mixing with the samples in liquid, the RPNCs may lead to the contamination of the samples being tested. In this paper, we incorporate one-dimensional oriented RPNCs with agarose gel film to prepare heterogeneous hydrogel films. Thanks to the non-responsive and porous nature of the agarose gel, the protons diffuse freely in the gel, which facilitates the fast response of the RPNCs. Furthermore, the “frozen” RPNCs in agarose gel not only enable the display of structural colors without the need for a magnet but also improve the cycling stability and long-term durability of the sensor, and will not contaminate the samples. This work paves the way for the application of photonic crystal sensors. Full article

(1) Background: Polysaccharide films are promising vehicles for the delivery of bioactive agents such as collagenases, as they provide controlled release at the wound site, facilitating tissue regeneration. This study aimed to investigate the physicochemical properties of Cassia grandis polysaccharide films with immobilized collagenase from Streptomyces parvulus (DPUA/1573). (2) Methods: Galactomannan was extracted from Cassia grandis seeds for film production with 0.8% (w/v) galactomannan and 0.2% (v/v) glycerol with or without collagenases. The films underwent physical-chemical analyses: Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), color and opacity (luminosity-L*, green to red-a*, yellow to blue-b*, opacity-Y%), moisture content, water vapor permeability (WVP), thickness, contact angle, and mechanical properties. (3) Results: The results showed similar FTIR spectra to the literature, indicating carbonyl functional groups. Immobilizing bioactive compounds increased surface roughness observed in SEM. TGA indicated a better viability for films with immobilized S. parvulus enzymes. Both collagenase-containing and control films exhibited a bright-yellowish color with slight opacity (Y%). Mechanical tests revealed decreased rigidity in PCF (−25%) and SCF (−41%) and increased deformability in films with the immobilized bioactive compounds, PCF (234%) and SCF (295%). (4) Conclusions: Polysaccharide-based films are promising biomaterials for controlled composition, biocompatibility, biodegradability, and wound healing, with a potential in pharmacological applications. Full article

Photoalignment by azo dye nanolayers can provide high alignment quality for large-area liquid crystal devices. Application of this technology to active optical elements for signal processing and communications is a hot topic of photonics research. In this article, we review recent demonstrations and performance of liquid crystal photonic devices, discuss the advantages of the proposed technology, and identify challenges and future prospects in the research field of photoaligned multi-domain liquid crystal structures. We believe that the developments discussed here can provide directions for future research and potential opportunities for applications of liquid crystal devices based on multi-domain photoalignment. Full article

Bioinspired structural color represents a burgeoning field that draws upon principles, strategies, and concepts derived from biological systems to inspire the design of novel technologies or products featuring reversible color changing mechanisms, with significant potential applications for camouflage, sensors, anticounterfeiting, etc. This mini-review focuses specifically on the research progress of bioinspired structural color in the realm of camouflage. Firstly, it discusses fundamental mechanisms of coloration in biological systems, encompassing pigmentation, structural coloration, fluorescence, and bioluminescence. Subsequently, it delineates three modulation strategies—namely, photonic crystals, film interference, and plasmonic modulation—that contribute to the development of bioinspired structural color materials or devices. Moreover, the review critically assesses the integration of bioinspired structural color materials with environmental contexts, with a particular emphasis on their application in camouflage. Finally, the paper outlines persisting challenges and suggests future development trends in the camouflage field via bioinspired structural color. Full article

Anthocyanin-based smart packaging has been widely used for food freshness monitoring, but it cannot meet the requirements of smart films with antibacterial properties. This study aimed to enhance the antibacterial properties of intelligent films by incorporating Amomum tsao-ko essential oil (AEO) for mantis shrimp spoilage tracking and keeping the product fresh. A smart film was designed by introducing AEO and purple potato anthocyanin (PPA) to a polyvinyl alcohol/cellulose nanocrystal (PVA/CNC) polymer matrix. Our findings revealed that APP and AEO imparted the smart film with a favorable oxygen barrier, UV protection, mechanical properties, and antioxidant and pH/NH₃-sensitive functions. Interestingly, the PVA/CNC-AEO-PPA film achieved 45.41% and 48.25% bactericidal efficacy against S. putrefaciens and V. parahaemolyticus, respectively. Furthermore, a visual observation confirmed that the target film (PVA/CNC-AEO-PPA) changed color significantly during mantis shrimp spoilage: rose red—light red—pink—light gray—dark gray. Meanwhile, the PVA/CNC-AEO-PPA film retarded the quality deterioration of the mantis shrimp effectively. The PVA/CNC-AEO-PPA film shows great application potential in mantis shrimp preservation and freshness monitoring; it is expected to become a rapid sensor for detecting seafood quality non-destructively and a multifunctional film for better preservation of product quality. Full article

Film and TV video scenes contain rich art and design elements such as light and shadow, color, composition, and complex affects. To recognize the fine-grained affects of the art carrier, this paper proposes a multitask affective value prediction model based on an attention mechanism. After comparing the characteristics of different models, a multitask prediction framework based on the improved progressive layered extraction (PLE) architecture (multi-headed attention and factor correlation-based PLE), incorporating a multi-headed self-attention mechanism and correlation analysis of affective factors, is constructed. Both the dynamic and static features of a video are chosen as fusion input, while the regression of fine-grained affects and classification of whether a character exists in a video are designed as different training tasks. Considering the correlation between different affects, we propose a loss function based on association constraints, which effectively solves the problem of training balance within tasks. Experimental results on a self-built video dataset show that the algorithm can give full play to the complementary advantages of different features and improve the accuracy of prediction, which is more suitable for fine-grained affect mining of film and TV scenes. Full article

The antibacterial microcapsules were prepared by encapsulating Toddalia asiatica (L.) Lam. extracts with urea–formaldehyde resin. The orthogonal test was designed to investigate the effects of the mass ratio of core and wall materials (W_core:W_wall), emulsifier concentration, reaction temperature and reaction time on the yield rate and coverage rate of microcapsules, and to obtain the best preparation technology for microcapsules. The single-factor results indicated that the maximum influence factor was the W_core:W_wall of the microcapsules; the larger the W_core:W_wall, the easier the microcapsules were to agglomerate; and when the W_core:W_wall was 0.8:1, the coverage rate reached the maximum value of 11.0%. The waterborne topcoat paint film was prepared by adding the microcapsules in the same content. The yield rate, coverage rate, and microscopic morphology of Toddalia asiatica (L.) Lam. extract microcapsules were analyzed, as well as the effects of microcapsules on the microscopic morphology, optical properties, cold liquid resistance, mechanical properties and antibacterial properties of a waterborne topcoat paint film. Combining the optical properties, cold liquid resistance, physical properties, and antibacterial properties of the waterborne topcoat paint film, the comprehensive performance of the waterborne topcoat paint film with the W_core:W_wall of 0.8:1 was superior. The gloss was 8.07 GU, color difference ΔE was 9.21, visible light transmittance was 82.90%, resistance to citric acid, ethanol and detergent were grade 1, 2 and 2, respectively, elongation at break was 15.68%, and roughness was 3.407 µm. The antibacterial activity against Escherichia coli and Staphylococcus aureus were 42.82% and 46.05%, respectively. In this study, a waterborne topcoat paint film with a microcapsule-coated plant-derived antibacterial agent as the core was prepared, expanding the application prospect of plant-derived antibacterial microcapsules. Full article

A novel aromatic imine derivative, 2′-(1,4-phenylene)bis[4-[(4-methoxyphenyl)methylene]-5(4H)-oxazolone] (PBMBO), was designed and synthesized as a yellow colorant additive for green color filters used in image sensors. The optical and thermal properties of the newly developed material were evaluated both in solution and within color filter film conditions. PBMBO demonstrated a molar extinction coefficient of 2.24 × 10⁴ L/mol·cm in solution, surpassing that of the commercially employed yellow colorant MBIQO by a factor of 1.82. Color resist (CR) films incorporating PBMBO exhibited outstanding optical characteristics, displaying 0.03% transmittance at 435 nm, 99.3% transmittance at 530 nm, and a sharp slope within the 400 to 550 nm range. The decomposition temperature of PBMBO was 303 °C, indicating relatively superior thermal stability compared to MBIQO. Consequently, PBMBO emerges as a highly promising candidate for a yellow colorant additive in imaging sensor color filters, owing to its exceptional optical and thermal stability. Its potential applications are anticipated to extend across various fields of organic semiconductors. Full article

Pomelo peel is a natural substance with antibacterial properties. Its extraction process is simple, and the raw materials are abundant. Microcapsules were prepared using melamine resin as the wall material and pomelo peel flavonoids as the core material. The optimization of microcapsule preparation was explored by orthogonal and single-factor experiments. The findings indicated that the optimum process for the preparation of microencapsulation was a 0.12:1 mass ratio of core to wall material, 60 °C microencapsulation reaction temperature, 800 rpm microencapsulation reaction stirring speed, and 2% emulsifier concentration. On this basis, the microcapsules were applied to waterborne coatings at different levels, 0%, 3.0%, 6.0%, 9.0%, 12.0%, and 15.0%, respectively, to prepare paint films, and the properties of the paint films were tested and explored. The test showed that the microcapsules added to the waterborne paint film exhibited antibacterial activity while retaining good optical and mechanical properties. In comparison with Escherichia coli, the microcapsules had a greater antibacterial rate against Staphylococcus aureus. When the content of microcapsules was 6.0%, the general performance of the waterborne paint film was optimal. The antibacterial rate of the paint film against Staphylococcus aureus and Escherichia coli was 40.5% and 50.5%, respectively. The color difference was 3.28. The paint film had a certain elasticity area, the elongation at break was 10.8%, and the roughness was 1.75 μm. We successfully prepared microcapsules capable of improving the antibacterial performance of waterborne paint film, which expands the application field of waterborne coatings and provides a certain reference value for the antibacterial research of waterborne coatings. Full article

Simple and sensitive determination of total antioxidant capacity (TAC) in food samples is highly desirable. In this work, an electrochemical platform was established based on a silica nanochannel film (SNF)-modified electrode, facilitating fast and highly sensitive analysis of TAC in colored food samples. SNF was grown on low-cost and readily available tin indium oxide (ITO) electrode. Fe³⁺-phenanthroline complex-Fe(III)(phen)₃ was applied as the probe, and underwent chemical reduction to form Fe²⁺-phenanthroline complex-Fe(II)(phen)₃ in the presence of antioxidants. Utilizing an oxidative voltage of +1 V, chronoamperometry was employed to measure the current generated by the electrochemical oxidation of Fe(II)(phen)₃, allowing for the assessment of antioxidants. As the negatively charged SNF displayed remarkable enrichment towards positively charged Fe(II)(phen)₃, the sensitivity of detection can be significantly improved. When Trolox was employed as the standard antioxidant, the electrochemical sensor demonstrated a linear detection range from 0.01 μM to 1 μM and from 1 μM to 1000 μM, with a limit of detection (LOD) of 3.9 nM. The detection performance is better that that of the conventional colorimetric method with a linear de range from 1 μM to 40 μM. Owing to the anti-interfering ability of nanochannels, direct determination of TAC in colored samples including coffee, tea, and edible oils was realized. Full article

Gelatin films are very versatile materials whose properties can be tuned through functionalization with different systems. This work investigates the influence of WO₃ nanoparticles on the swelling, barrier, mechanical, and photochromic properties of gelatin films. To this purpose, polyvinylpirrolidone (PVP)-stabilized WO₃ nanoparticles were loaded on gelatin films at two different pH values, namely, 4 and 7. The values of swelling and solubility of functionalized films displayed a reduction of around 50% in comparison to those of pristine, unloaded films. In agreement, WO₃ nanoparticles provoked a significant decrease in water vapor permeability, whereas the decrease in the values of elastic modulus (from about 2.0 to 0.7 MPa) and stress at break (from about 2.5 to 1.4 MPa) can be ascribed to the discontinuity created by the nanoparticles inside the films. The results of differential scanning calorimetry and X-ray diffraction analysis suggest that interaction of PVP with gelatin reduce gelatin renaturation. No significant differences were found between the samples prepared at pH 4 and 7, whereas crosslinking with glutaraldehyde greatly influenced the properties of gelatin films. Moreover, the incorporation of WO₃ nanoparticles in gelatin films, especially in the absence of glutaraldehyde, conferred excellent photochromic properties, inducing the appearance of an intense blue color after a few seconds of light irradiation and providing good resistance to several irradiation cycles. Full article