Degree Of Oxidation Research Articles

Synthesis, XPS and NEXAFS spectroscopy study of Zn, Cr codoped bismuth tantalate pyrochlores

The study investigated the formation of inhomophase ceramics through Zn doping in Bi2СrTa2O9.5–Δ. It was found that all Bi2ZnxCr1–xTa2O9.5–Δ (0.3 ≤ x ≤ 0.7) investigated samples crystallized in the pyrochlore structural type (sp. Gr. Fd-3m) and contained an admixture of triclinic β-BiTaO4 (up to 24 wt %, sp. gr. P-1), with the admixture concentration proportional to the degree of zinc doping. It was shown that impurities in the samples could be eliminated by creating a defective bismuth sublattice proportional to the impurity content, resulting in single-phase Bi2–yZnxCr1–xTa2O9.5–Δ (y ≤ 0.5, 0.3 ≤ x ≤ 0.7) samples with the pyrochlore structure. The unit cell parameter of pyrochlore increased with an increase in zinc ion content in the samples from 10.4493 Å (x = 0.3) to 10.4976 Å (x = 0.7). The microstructure of ceramics was represented by individual slightly melted grains 0.5–2 μm in size, which increased in size and fuse with each other with an increase in zinc content. The near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) data showed that zinc doping did not change the oxidation degree of bismuth and tantalum in pyrochlore, with the ions in charge states Bi(+3), Zn(+2) and Ta(+5). The study also observed an energy shift of the absorption band in the Ta 4f spectrum toward lower energies (ΔE = 0.55 eV) characteristic of tantalum ions with an effective charge (+5–δ) and a shift of the Bi 4f7/2 and Bi 4f5/2 bands shift to lower energies with increase in x(Zn), due to the distribution of some Zn(II) ions in the bismuth position. The oxidation degree of chromium ions in the samples was mainly (+3), with some chromium ions oxidized and having an oxidation degree close to (+6) according to NEXAFS data. The studied ceramics showed promise as dielectrics for multilayer ceramic capacitors and devices for microwave applications due to their low sintering temperature and high porosity.

Variability in molecular composition and optical absorption of atmospheric brown carbon aerosols in two contrasting urban areas of China

Atmospheric brown carbon (BrC) aerosols were investigated at two urban sites in southern (Hefei) and northern (Shijiazhuang) China during summer and winter of 2019–2020 to explore regional variability in their compositional and optical properties. Organic matter in ambient PM2.5 samples were characterized at molecular level using ultrahigh performance liquid chromatography coupled with a diode array detector and an Orbitrap mass spectrometer. Although the molecular composition of organic aerosols varied substantially over different ambient environments, they were mainly composed by CHO and CHON species in positive ionization mode while CHO and CHOS species in negative mode. The mass absorption coefficients of BrC aerosols at wavelength range 250–450 nm were relatively higher for winter samples in both cities and for Shijiazhuang samples in both seasons, partly attributed to the higher concentration levels of anthropogenic air pollutants in these environments. The absorption Ångström exponents further revealed that BrC aerosols in winter seasons and in Shijiazhuang had a greater capacity of absorption at shorter wavelengths. A total of 26 BrC species with strong absorption were unambiguously identified from different environments, which mainly consisted of CHO, CHON, and CHN species and had higher degrees of unsaturation and lower degrees of oxidation. The presence and abundance of these BrC species varied dynamically across the seasons and cities, with a greater number of species presented in the winter of Shijiazhuang. The BrC species together contributed 12–26 % in the total absorbance of light-absorbing organic components at 250–450 nm. This study highlights the regional differences in BrC properties influenced by the sources and atmospheric processes, which should be taken into account to assess their climate impacts.

High temperature oxidation behavior of CoCrFeNiMo0.2 high-entropy alloy coatings produced by laser cladding

The oxidation behavior of CoCrFeNiMo0.2 high-entropy alloy laser cladding coatings at 700°C and 900°C was investigated. The oxidation kinetics of the alloys at all temperatures followed a parabolic behavior, with the oxidation rates increasing significantly with increasing temperature. The alloy exhibits excellent oxidation resistance at 700 °C. Compared with the original alloy structure, the segregation of Mo element in the alloy is more serious after high-temperature treatment. Compared with 700 °C, the oxidation degree of the alloy is more intense at 900 °C. The reaction between iron and chromium oxides forms a chromite layer, and the rapid diffusion of iron ions in the layer forms an outer layer of iron oxides. As the oxidation proceeds, the oxide film is separated from the metal, and the chromium oxide layer grows between the spinel layer and the metal. The thermodynamics of the reaction was calculated, the oxidation mechanism of the alloy was explored, and a high-temperature model of the alloy was developed. This study expands the potential applications of high entropy alloys in surface engineering.

Synthesis of graphene oxide: Effect of sonication during oxidation

The oxidation of graphite to graphene oxide (GO) is a widely used approach to exfoliate graphite. Nevertheless, achieving precise control over the degree of oxidation and the resulting properties of GO has considerable challenges. In this study, we demonstrate that using sonication during the oxidation of graphite by Hummers' method alters the chemistry and properties of the GO. Contrary to our expectations, we found that sonication slows the oxidation of graphite by impeding the intercalation of sulfuric acid. This results in fewer oxygen-containing functional groups on the GO and minimizes functionalization of the basal plane of the graphene oxide sheets, leading to superior electrochemical and mechanical properties of GO-based composites compared to GO synthesized without sonication. In this study, we use X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared spectroscopy (FTIR), cyclic voltammetry, and compression testing to quantify the effects of sonication during oxidation and propose the mechanism leading to those effects.

High performance self-assembled sulfidized nanoscale zero-valent iron for the immobilization of cadmium in contaminated sediments: Optimization, microbial response, and mechanisms

Sulfidized nanoscale zero-valent iron (S-nZVI) showed excellent removal capacity for cadmium (Cd) in aqueous phase. However, the remediation effects of S-nZVI on Cd-contaminated sediment and its interactions with microorganisms in relation to Cd fate remain unclear. The complexity of the external environment posed a challenge for Cd remediation. This study synthesized S-nZVI with different S and Fe precursors to investigate the effect of precursors and applied the optimal material to immobilize Cd in sediments. Characterization analysis revealed that the precursor affected the morphology, Fe0 crystallinity, and the degree of oxidation of the material. Incubation experiments demonstrated that the immobilization efficiency of Cd using S-nZVIFe3++S2- (S/Fe = 0.14) reached the peak value of 99.54%. 1% and 5% dosages of S-nZVI significantly reduced Cd concentration in the overlying water, DTPA-extractable Cd content, and exchangeable (EX) Cd speciation (P < 0.05). Cd leaching in sediment and total iron in the overlying water remained at low levels during 90 d of incubation. Notably, each treatment maintained a high Cd immobilization efficiency under different pH, water/sediment ratio, organic acid, and coexisting ion conditions. Sediment physicochemical properties, functional bacteria, and a range of adsorption, complexation and precipitation of CdS effects dominated Cd immobilization.

The NMR relaxivity of gadolinium (III) solutions as the function of oxidation level and flake size of graphene oxide

Chelating by graphene oxide (GO) results in dramatic shortening of the proton relaxation times of Gd3+ aqueous solutions. However, the factors, leading to the increase of relaxivity values, and the mechanisms behind the observed phenomena remain elusive. In this work, we investigated how the relaxation times of the GO/Gd3+ solutions depend on the oxidation level and the flake size of GO. The values of spin-lattice (r1) and spin-spin (r2) relaxivities increase with the oxidation degree of the used GO samples. The relaxivity also increases with decreasing the particle size of GO flakes by sonication. The observed phenomena are explained by the increase in the number of the edge functional groups, generated under the influence of both parameters. The content of these groups, their formation, and chelation of Gd3+ ions is discussed in the manuscript. Viscosity of solutions does not directly affect the relaxation times. With the use of high oxidation level and small particle size GO samples we have registered the record high relaxivity values: r2 = 114.7 mM−1 s−1, and r1 = 97.0 mM−1 s−1. This opens straight routes for developing the GO/Gd3+ based MRI contrast agents.

Study on wear protection performance of HVAF WC–Cr3C2–Ni coatings deposited on crystallizer surface

A crystallizer is the most crucial component of the continuous casting and rolling process, and it is required to operate effectively at high temperatures and loads for an extended period. In this study, WC–Cr3C2–Ni cermet coatings with high strength and wear resistance were deposited on the surface of a copper alloy crystallizer using high-velocity air-fuel spraying. The microstructure of the coating and its protective effect on the substrate at different temperatures were analyzed. The coating on the copper substrate was uniform and dense, with a porosity of 0.34 % and stable phases. Wear test results at room temperature showed that copper substrate underwent oxidative peeling failure when subjected to wear, and exhibited severe abrasive and adhesive wear, while WC–Cr3C2–Ni coating had no peeling damage on the surface when subjected to wear. In addition, the friction coefficient of the substrate was reduced from 0.624 to 0.489, thus significantly improving the wear resistance of the crystallizer surface. At high temperature (300 °C), the friction coefficient of coating increased to 0.676. Although the degree of oxidation and fatigue wear of the coating increased, the surface of the coating remained intact without any failure area. WC–Cr3C2–Ni coating protected the crystallizer continuously under high-temperature loading conditions for a prolonged time, indicating enhanced service life of the crystallizer. This study provides significant findings for developing new crystallizer coatings.

Polymer Composites with Carbon Fillers Based on Coal Pitch and Petroleum Pitch Cokes: Structure, Electrical, Thermal, and Mechanical Properties.

The effect of particle size and oxidation degree of new carbon microfillers, based on coal pitch (CP) and petroleum pitch (PET) cokes, on the structure as well as thermal, mechanical, and electrical properties of the composites based on ultrahigh molecular weight polyethylene (UHMWPE) was investigated. The composites studied have a segregated structure of filler particle distribution in the UHMWPE matrix. It was found that composite with smaller CP grain fraction has the highest Young's modulus and electrical conductivity compared to the other composites studied, which can be the result of a large contribution of flake-shaped particles. Additionally, conductivity of this composite turned out to be similar to composites with well-known carbon nanofillers, such as graphene, carbon black, and CNTs. Additionally, the relationship between electrical conductivity and Young's modulus values of composites studied was revealed, which indicates that electrical conductivity is very sensitive to the structure of the filler phase in the polymer matrix. In general, it was established that the properties, especially the electrical conductivity, of the composites studied strongly depends on the size, shape, and oxidative treatment of CP and PET filler particles, and that the CP coke of appropriately small particle sizes and flake shape has significant potential as a conductive filler for polymer composites.

Influence of Synthesis Parameters on the Short-Range Structure and Electrochemical Performances of Li2MnO2F.

In the last years, disordered rocksalt structure (DRS) materials were proposed as a positive electrode for lithium-ion batteries. In particular, the fluorinated DRS materials were proposed to be more stable upon cycling than pure oxide counterparts. These materials are mainly obtained by mechanosynthesis in order to incorporate a significant number of F ions and maintain a disordered structure. Since the local structural arrangement is crucial for battery application, we aim to monitor its evolution upon the synthesis of Li2MnO2F from two sets of precursors: Mn2O3, Li2O, and LiF or LiMnO2 and LiF. The synthesis progress was thus followed, by 7Li and 19F MAS NMR coupled to XRD to probe the structure at different scales. This allowed us to identify an optimal milling time to reach the final compounds. We show that they exhibit similar morphology (by SEM), medium- and short-range orders (by XRD, 7Li and 19F NMR, EXAFS), and average Mn oxidation degree (by XANES). The electrochemical performances of the two compounds are almost similar, with high specific capacities of 319 mAh·g-1 ("from LiMnO2") and 304 mAh·g-1 ("from Mn2O3") for the first charge to 4.8 V vs Li+/Li, proving their interest as post-NMC candidates as positive electrode materials.

Polyarene Oxides with Tunable Quinone Units for Photocatalytic CO2 Reduction: A Simple Strategy toward Effective and Selective Catalysts.

The photocatalytic transformation of carbon dioxide (CO2) into valuable chemicals is a challenging process that requires effective and selective catalysts. However, most polymer-based photocatalysts with electron donor-acceptor (D-A) structures are synthesized with a fixed D-A ratio by using expensive monomers. Herein, we report a simple strategy to prepare polyarene oxides (PAOs) with quinone structural units via oxidation treatment of polyarene (PA). The resultant PAOs show tunable D-A structures and electronic band positions depending on the degree of oxidation, which can catalyze the photoreduction of CO2 with water under visible light irradiation, generating CO as the sole carbonaceous product without H2 generation. Especially, the PAO with an oxygen content of 17.6% afforded the highest CO production rate of 161.9 μmol g-1 h-1. It is verified that the redox transformation between quinone and phenolic hydroxyl in PAOs achieves CO2 photoreduction coupled with water oxidation. This study provides a facile way to access conjugated polymers with a tunable D-A structure and demonstrates that the resultant PAOs are promising photocatalysts for CO2 reduction.

Effect of oxidation degree of iron-based oxygen carriers on their mechanical strength

Iron-based oxygen carriers are currently one of the most popular choices for chemical looping processes. In order to minimize losses of oxygen carrier materials in the system, it is important to assess attrition characteristics. Furthermore, in chemical looping gasification where the oxygen transfer capacity needs to be limited, a higher reduction degree of oxygen carriers can be expected. As different oxidation degrees lead to different phase compositions, this study aimed to investigate the correlation between mechanical strength of iron-based oxygen carriers and the phase composition, which is the result of oxidation degree change. Our findings demonstrate that how the phase composition may affect the attrition rate of oxygen carriers depends largely on the type of the material itself. In this study, the presence of Fe-Ti and Fe-Si combinations contribute to a generally stable attrition rate, while Fe-Ca system exhibits a decreasing attrition rate. Furthermore, attrition rate shows a more conclusive trend compared to crushing strength. Among the investigated materials, both ilmenite ore and iron sand showed a robust, stable mechanical stability with an attrition rate of approximately 0.5–1 wt%/h, which is on par with that of sand (0.5 wt%/h). The attrition rates of LD slag and mill scale are lower, about 1–3 wt%/h.

Sonochemical synthesis of SnS and SnS2 quantum dots from aqueous solutions, and their photo- and sonocatalytic activity

Our study reports the ultrasound-assisted synthesis of SnS and SnS2 in the form of nanoparticles using aqueous solutions of respective tin chloride and thioacetamide varying sonication time. The presence of both compounds is confirmed by powder X-ray diffraction, energy-dispersive X-ray spectroscopy, as well as Raman and FT-IR spectroscopic techniques. The existence of nanoparticles is proven by powder X-ray diffraction investigation and by high resolution transmission electron microscopy observations. The size of nanocrystallites are in the range of 3–8 nm and 30 50 nm for SnS, and 1.5–10 nm for SnS2. X-ray photoelectron spectroscopy measurements, used to investigate the chemical state of tin and sulphur atoms on the surface of nanoparticles, reveal that they are typically covered with tin on the same oxidation degree as respective bulk compound. Values of optical bandgaps of synthesized nanoparticles, according to the Tauc method, were 2.31, 1.47 and 1.05 eV for SnS (60, 90 and 120 min long synthesis, respectively), and 2.81, 2.78 and 2.70 eV for SnS2 (60, 90 and 120 min long synthesis, respectively). Obtained nanoparticles were utilized as photo- and sonocatalysts in the process of degradation of model azo-dye molecules by UV-C light or ultrasound. Quantum dots of SnS2 obtained under sonication lasting 120 min were the best photocatalyst (66.9 % color removal), while quantum dots of SnS obtained under similar sonication time were the best sonocatalyst (85.2 % color removal).

Analysis of Effectiveness of Bottom Stirring after the Modernization on Basic Oxygen Furnace in HBIS Serbia Group

The significant modernization effort in the steel shop at HBIS Group Serbia is the introduction of a Basic Oxygen Furnace, which features bottom stirring with argon and nitrogen, along with the capability for slag splashing with nitrogen through the lance tip after steel tapping from the converter. Implementing this new technology presented a challenge, as it was our first encounter with such advancements. The primary objectives of this modernization were to achieve a lower dissolved oxygen content in steel while reaching the targeted carbon level at the end of the blowing process. This aims to optimize the steel's oxidation degree [%C] [%O], reduce the use of Al as a deoxidizer, increase yield, and achieve a low phosphorus content in steel at the end of blowing. Additionally, it aimed to increase the lining's lifetime through slag splashing and decrease the refractory mass consumption needed for lining repairs. This analysis covers a 7-month period since the start of the campaign with the new refractory lining, based on research conducted on 3,150 heats. Our examination of the process led us to conclude that while certain parameters met our expectations, some results did not reach the anticipated level.

Mussel inspired sequential protein delivery based on self-healing injectable nanocomposite hydrogel

Polysaccharide based self-healing and injectable hydrogels with reversible characteristics have widespread potential in protein drug delivery. However, it is a challenge to design the dynamic hydrogel for sequential release of protein drugs. Herein, we developed a novel mussel inspired sequential protein delivery dynamic polysaccharide hydrogel. The nanocomposite hydrogel can be fabricated through doping polydopamine nanoparticles (PDA NPs) into reversible covalent bond (imine bonds) crosslinked polymer networks of oxidized hyaluronic acid (OHA) and carboxymethyl chitosan (CEC), named PDA NPs@OHA-l-CEC. Besides multiple capabilities (i.e., injection, self-healing, and biodegradability), the nanocomposite hydrogel can achieve sustained and sequential protein delivery of vascular endothelial growth factor (VEGF) and bovine serum albumin (BSA). PDA NPs doped in hydrogel matrix serve dual roles, acting as secondary protein release structures and form dynamic non-covalent interactions (i.e., hydrogen bonds) with polysaccharides. Moreover, by adjusting the oxidation degree of OHA, the hydrogels with different crosslinking density could control overall protein release rate. Analysis of different release kinetic models revealed that Fickian diffusion drove rapid VEGF release, while the slower BSA release followed a Super Case II transport mechanism. The novel biocompatible system achieved sequential release of protein drugs has potentials in multi-stage synergistic drug deliver based on dynamic hydrogel.

Solid Wood Modification toward Anisotropic Elastic and Insulative Foam-Like Materials.

The methods used to date to produce compressible wood foam by top-down approaches generally involve the removal of lignin and hemicelluloses. Herein, we introduce a route to convert solid wood into a super elastic and insulative foam-like material. The process uses sequential oxidation and reduction with partial removal of lignin but high hemicellulose retention (process yield of 72.8%), revealing fibril nanostructures from the wood's cell walls. The elasticity of the material is shown to result from a lamellar structure, which provides reversible shape recovery along the transverse direction at compression strains of up to 60% with no significant axial deformation. The compressibility is readily modulated by the oxidation degree, which changes the crystallinity and mobility of the solid phase around the lumina. The performance of the highly resilient foam-like material is also ascribed to the amorphization of cellulosic fibrils, confirmed by experimental and computational (molecular dynamics) methods that highlight the role of secondary interactions. The foam-like wood is optionally hydrophobized by chemical vapor deposition of short-chained organosilanes, which also provides flame retardancy. Overall, we introduce a foam-like material derived from wood based on multifunctional nanostructures (anisotropically compressible, thermally insulative, hydrophobic, and flame retardant) that are relevant to cushioning, protection, and packaging.

Changes in volatile compounds and lipid oxidation in various tissues of Nile tilapia (Oreochromis niloticus) during ice storage.

Changes in the lipid oxidation and volatile compounds of a variety of tilapia tissues (Oreochromis niloticus) including the muscle, gills, and skin during ice storage were investigated by evaluating peroxide values (PVs), lipoxygenase (LOX) activity, fatty acid (FA) composition, and volatile substances. LOX activity and PV were determined in the gills, skin, and muscles throughout 9 days of storage in ascending order to the extended storage time. The highest level of LOX activity was found in the gills, whereas the highest PV was determined in the skin. FA content of all tissues decreased during the storage period. Oleic acid was the predominant monounsaturated fatty acid, whereas linoleic acid and docosahexaenoic acid were the main polyunsaturated fatty acids and omega-3 in all tissues. The fish gills were shown to have the highest level of volatile compounds followed by the skin and muscle, based on headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. Principal component analysis indicated gradual changes in the volatile compound composition with increasing storage time. 2-Butanone and nonanal in the muscle, 6-methyl-2-heptanone and 2-nonenal in the gills, and 1-heptanol, and 1-nonanol in the skin were found to be the potential freshness indicators. In addition, hexanal could be a general potential marker for measuring the degree of lipid oxidation in all tissues. PRACTICAL APPLICATION: Understanding the volatile compound formation related to lipid oxidation within storage time at various tissues of tilapia could be critical to the side-stream processing to yield the desired quality.

Silver-doped graphite oxide composites used as antimicrobial agents against Staphylococcus aureus, Escherichia coli and Tatumella terrea evaluated by direct TLC bioautography

Silver-doped graphite oxide composites presented mixed Ag and Ag2O crystalline phases accompanied by C/O and ID/IG average ratios of 2.13 and 1.16, associated with a good oxidation degree and high structural disorder or defects in the carbon material, respectively. The low-silver-doped GrO composite showed homogenous silver particle dispersion and a low particle size distribution (96 nm). However, high-silver-doped GrO composites generated materials with high relative crystallinity, silver particle agglomeration, and Ag metal phase promotion. At 3 and 5 mg ml−1 per chromatographic plate, the silver-doped graphite oxide composites were tested by direct TLC bioautography against Staphylococcus aureus, Escherichia coli, and Tatumella terrea microorganisms, where the minimum inhibitory concentration was 3 mg ml−1 per chromatographic plate. At 3.0 mg ml−1 per chromatographic plate, high-silver-doped GrO composites exhibited a 39%, 3.2-fold, and 83% higher retention factor (R f ) compared with the composites with low-silver-doped GrO composites against S. aureus, E. coli, and T. terra microorganisms, respectively. However, both composites showed similar inhibition capacities at 5.0 mg ml−1 per chromatographic plate against the three microorganisms. This behavior may be associated with both composites reaching the threshold limit. In general, the silver acetate amount used in the silver-doped GrO composites influenced the dispersion, crystalline phase promotion, particle size distribution, and the silver particle release capacity, which modified the electrostatic adsorption type between the composites and the bacterial cell walls.

Characterization of the Effects of Low-Sodium Salt Substitution on Sensory Quality, Protein Oxidation, and Hydrolysis of Air-Dried Chicken Meat and Its Molecular Mechanisms Based on Tandem Mass Tagging-Labeled Quantitative Proteomics.

The effects of low-sodium salt mixture substitution on the sensory quality, protein oxidation, and hydrolysis of air-dried chicken and its molecular mechanisms were investigated based on tandem mass tagging (TMT) quantitative proteomics. The composite salt formulated with 1.6% KCl, 0.8% MgCl2, and 5.6% NaCl was found to improve the freshness and texture quality scores. Low-sodium salt mixture substitution significantly decreased the carbonyl content (1.52 nmol/mg), surface hydrophobicity (102.58 μg), and dimeric tyrosine content (2.69 A.U.), and significantly increased the sulfhydryl content (74.46 nmol/mg) and tryptophan fluorescence intensity, suggesting that protein oxidation was inhibited. Furthermore, low-sodium salt mixture substitution significantly increased the protein hydrolysis index (0.067), and cathepsin B and L activities (102.13 U/g and 349.25 U/g), suggesting that protein hydrolysis was facilitated. The correlation results showed that changes in the degree of protein hydrolysis and protein oxidation were closely related to sensory quality. TMT quantitative proteomics indicated that the degradation of myosin and titin as well as changes in the activities of the enzymes, CNDP2, DPP7, ABHD12B, FADH2A, and AASS, were responsible for the changes in the taste quality. In addition, CNDP2, ALDH1A1, and NMNAT1 are key enzymes that reduce protein oxidation. Overall, KCl and MgCl2 composite salt substitution is an effective method for producing low-sodium air-dried chicken.

Direct in Situ Fabrication of Multicolor Afterglow Carbon Dot Patterns with Transparent and Traceless Features via Laser Direct Writing.

Multicolor afterglow patterns with transparent and traceless features are important for the exploration of new functionalities and applications. Herein, we report a direct in situ patterning technique for fabricating afterglow carbon dots (CDs) based on laser direct writing (LDW) for the first time. We explore a facile step-scanning method that reduces the heat-affected zone and avoids uneven heating, thus producing a fine-resolution afterglow CD pattern with a minimum line width of 80 μm. Unlike previous LDW-induced luminescence patterns, the patterned CD films are traceless and transparent, which is mainly attributed to a uniform heat distribution and gentle temperature rise process. Interestingly, by regulating the laser parameters and CD precursors, an increased carbonization and oxidation degree of CDs could be obtained, thus enabling time-dependent, tunable afterglow colors from blue to red. In addition, we demonstrate their potential applications in the in situ fabrication of flexible and stretchable optoelectronics.

A Colorimetric Nanofiber Film Based on Ethyl Cellulose/Gelatin/Purple Sweet Potato Anthocyanins for Monitoring Pork Freshness.

In this study, colorimetric indicator nanofiber films based on ethyl cellulose (EC)/gelatin (G) incorporating purple sweet potato anthocyanins (PSPAs) were designed via electrospinning technology for monitoring and maintaining the freshness of pork. The film presented good structural integrity and stability in a humid environment with water vapor permeability (WVP) of 6.07 ± 0.14 × 10-11 g·m-1s-1Pa-1 and water contact angle (WCA) of 81.62 ± 1.43°. When PSPAs were added into the nanofiber films, the antioxidant capacity was significantly improved (p < 0.05) with a DPPH radical scavenging rate of 68.61 ± 1.80%. The nanofiber films showed distinguishable color changes as pH changes and was highly sensitive to volatile ammonia than that of casting films. In the application test, the film color changed from light pink (fresh stage) to light brown (secondary freshness stage) and then to brownish green (spoilage stage), indicating that the nanofiber films can be used to detect the real-time freshness of pork during storage. Meanwhile, it could prolong the shelf life of pork by inhibiting the oxidation degree. Hence, these results suggested that the EC/G/PSPA film has promising future for monitoring freshness and extending shelf life of pork.