Search Results (692)

Photovoltaic–thermal (PVT) technology has attracted considerable attention for its ability to significantly improve solar energy conversion efficiency by simultaneously providing electricity and heat during the day. PVT technology serves a purpose in condensers and subcoolers for passive cooling in refrigeration systems at night. In our previous work, we proposed a switchable film-insulated photovoltaic–thermal–passive cooling (PVT-PC) module to address the structural incompatibility between diurnal and nocturnal modes. However, the performance of the proposed module strongly depends on two key design parameters: the structural height and the vacuum level of the air cushion. In this study, a numerical model of the proposed module is developed to examine the impact of design and meteorological parameters on its all-day performance. The results show that diurnal performance remains stable across different structural heights, while nocturnal passive cooling power shows strong dependence on vacuum level and structural height, achieving up to 103.73 W/m² at 10 mm height and 1500 Pa vacuum, which is comparable to unglazed PVT modules. Convective heat transfer enhancement, induced by changes in air cushion shape, is identified as the primary contributor to improved nocturnal cooling performance. Wind speed has minimal impact on electrical output but significantly enhances thermal efficiency and nocturnal convective cooling power, with a passive cooling power increase of up to 31.61%. In contrast, higher sky temperatures degrade nocturnal cooling performance due to diminished radiative exchange, despite improving diurnal thermal efficiency. These findings provide fundamental insights for optimizing the structural design and operational strategies of PVT-PC systems under varying environmental conditions. Full article

In recent years, active packaging has become a focal point of research and development in the food industry, driven by increasing consumer demand for safe, high-quality, and sustainable food products. In this work, solvent casting processed an active antibacterial multicomponent film based on hydroxypropyl methylcellulose incorporated with ferulic acid and chitin nanofibers. The influences of ferulic acid and different content of chitin nanofibers on the structure, thermal, mechanical, and water vapor stability and antioxidant and antibacterial efficiency of films were studied. It was shown that the inclusion of only ferulic acid did not significantly influence the mechanical, water vapor, and thermal stability of films. In addition, films containing only ferulic acid did not display antibacterial activity. The optimal concentration of chitin nanofibers in hydroxypropyl methylcellulose–ferulic acid films was 5 wt%, providing a tensile strength of 15 MPa, plasticity of 52%, and water vapor permeability of 0.94 × 10⁻⁹ g/m s Pa. With further increase of chitin nanofibers content, films with layered and discontinuous phases are obtained, which negatively influence tensile strength and water vapor permeability. Moreover, only films containing both ferulic acid and chitin nanofibers demonstrated antibacterial activity toward E. coli and S. aureus, suggesting that the presence of fibers allows easier release of ferulic acid from the matrix. These results imply that the investigated three-component systems have potential applicability as sustainable active food packaging materials. Full article

The rising demand for sustainable protein is driving interest in insects as a raw material for advanced food ingredients. This review collates and critically analyses over 300 studies on the conversion of crickets, mealworms, black soldier flies, and other farmed species into powders, protein isolates, oils, and chitosan-rich fibers with targeted techno-functional roles. This survey maps how thermal pre-treatments, blanch–dry–mill routes, enzymatic hydrolysis, and isoelectric solubilization–precipitation preserve or enhance the water- and oil-holding capacity, emulsification, foaming, and gelation, while also mitigating off-flavors, allergenicity, and microbial risks. A meta-analysis shows insect flours can absorb up to 3.2 g of water g⁻¹, stabilize oil-in-water emulsions for 14 days at 4 °C, and form gels with 180 kPa strength, outperforming or matching eggs, soy, or whey in specific applications. Case studies demonstrate a successful incorporation at 5–15% into bakery, meat analogs and dairy alternatives without sensory penalties, and chitin-derived chitosan films extend the bread shelf life by three days. Comparative life-cycle data indicate 45–80% lower greenhouse gas emissions and land use than equivalent animal-derived ingredients. Collectively, the evidence positions insect-based ingredients as versatile, safe, and climate-smart tools to enhance food quality and sustainability, while outlining research gaps in allergen mitigation, consumer acceptance, and regulatory harmonization. Full article

The intense demand for alternatives to conventional plastics has increasingly motivated the development of biodegradable packaging. However, the ecological impact of these materials when discarded in natural settings has not yet been evaluated. Therefore, this study investigated the effects of films based on chia mucilage in different aquatic environments. The solubilization time varied according to water type, ranging from 40 min in ultrapure, deionized, and distilled water to 230 min in saline water. After solubilization, all water samples exhibited increased turbidity (from 1.04 to 15.73 NTU in deionized water) and apparent color (from 0 to 44 PCU in deionized water) as well as pH variations depending on ionic strength. Deionized water also showed the highest viscosity increase (>350 Pa·s at 1 s⁻¹). UV–Vis spectra revealed a moderate rise in absorbance between 236 and 260 nm, indicating organic compound release. Regarding phytotoxicity, the solubilized films had no toxic effect and promoted a biostimulating effect on root elongation, with Relative Germination Index values exceeding 140% in most samples. These results reinforce the potential of chia-based films for controlled disposal, particularly in low-salinity environments, while highlighting the importance of evaluating post-solubilization interactions with aquatic systems. Full article

In this paper, a series of polyaniline (PANI)/Ti₃C₂ MXene composites (PMCs) with a biomimetic structure were prepared and employed as an anticorrosion coating application. First, the PANI was synthesized by oxidative polymerization with ammonium persulfate as the oxidant. Then, 2D Ti₃C₂ MXene nanosheets were prepared by treating the Ti₃AlC₂ using the optimized minimally intensive layer delamination (MILD) method, followed by characterization via XRD and SEM. Subsequently, the PMC was prepared by the oxidative polymerization of aniline monomers in the presence of Ti₃C₂ MXene nanosheets, followed by characterization via FTIR, XRD, SEM, TEM, CV, and UV–Visible. Eventually, the PMC coatings with the artificial biomimetic surface structure of a macaw feather were prepared by the nano-casting technique. The corrosion resistance of the PMC coatings, evaluated via Tafel polarization and Nyquist impedance measurements, shows that increasing the MXene loading up to 5 wt % shifts the corrosion potential (E_corr) on steel from −588 mV to −356 mV vs. SCE, reduces the corrosion current density (I_corr) from 1.09 µA/cm² to 0.035 µA/cm², and raises the impedance modulus at 0.01 Hz from 67 kΩ to 3794 kΩ. When structured with the hierarchical feather topography, the PMC coating (Bio-PA-MX-5) further advances the E_corr to +103.6 mV, lowers the I_corr to 7.22 × 10⁻⁴ µA/cm², and boosts the impedance to 96,875 kΩ. Compared to neat coatings without biomimetic structuring, those with engineered biomimetic surfaces showed significantly improved corrosion protection performance. These enhancements arise from three synergistic mechanisms: (i) polyaniline’s redox catalysis accelerates the formation of a dense passive oxide layer; (ii) MXene nanosheets create a tortuous gas barrier that cuts the oxygen permeability from 11.3 Barrer to 0.9 Barrer; and (iii) the biomimetic surface traps air pockets, raising the water contact angle from 87° to 135°. This integrated approach delivers one of the highest combined corrosion potentials and impedance values reported for thin-film coatings, pointing to a general strategy for durable steel protection. Full article

Heterojunctions are commonly used in optoelectronic devices to improve device performance. However, interface defects and lattice mismatch often hinder carrier transport and reduce efficiency, emphasizing the need for further exploration of diverse heterojunction structures. In this study, a heterojunction device constructed from Bi₂O₃ and Ga₂O₃ is demonstrated. The microstructures and photoelectrical properties of Bi₂O₃ and Ga₂O₃ thin films were investigated. Bi₂O₃ and Ga₂O₃ thin films show a bandgap of 3.19 and 5.10 eV. The Bi₂O₃/Ga₂O₃ heterojunction-based device demonstrates rectification characteristics, with a rectification ratio of 2.72 × 10³ at ±4.5 V and an ON/OFF ratio of 1.07 × 10⁵ (4.5/−3.9 V). Additionally, we fabricated a sandwich-structured photodetector based on the Bi₂O₃/Ga₂O₃ heterojunction and investigated its ultraviolet photoresponse performance. The photodetector exhibits low dark current (0.34 pA @ −3.9 V) and fast response rise/fall time (<40/920 ms). This work offers important perspectives on the advancement of large-area, low-cost, and high-speed Bi₂O₃ film-based heterojunction photodetectors. Full article

The mechanical properties of cell scaffolds are strongly influenced by their hydration state. In this study, we investigated the effect of the aqueous phase on the elastic modulus of chitosan hydrogel films using two complementary techniques: uniaxial tensile testing and atomic force microscopy (AFM) nanoindentation. Our results demonstrate that hydration markedly reduced the elastic modulus, decreasing from approximately 2 GPa in dry films to 120 kPa in swollen films, primarily due to the plasticizing effect of water. Moreover, hydrogel films in equilibrium with the aqueous phase exhibited a Young’s modulus three times lower than that of swollen films not in equilibrium. Raman spectroscopy further reveals a solvent “squeeze-out” phenomenon, as evidenced by an increased signal intensity in the 850–1200 cm⁻¹ region for stretched films that were out of swelling equilibrium, whereas equilibrated films showed stable spectral features. These findings highlight the crucial role of hydration dynamics in determining the mechanical behavior of chitosan hydrogel films, offering valuable insights for tailoring their properties in biomedical scaffold applications. Full article

Non-uniform friction and lubrication are the key factors affecting the surface quality of the casting billet. Based on the three-layer structure of the casting powder in the mold, the frictional stress in the mold was calculated and analyzed by using the relationship between the frictional stress and the thickness and viscosity of the liquid slag film, and the lubrication state between the cast billet and the mold was evaluated. Based on the actual production data of 40Mn2 steel and combined with the numerical simulation results of the solidification and shrinkage process of the molten steel in the mold by ANSYS 2022 R1 software, the frictional stress on the cast billet in the mold was calculated. It was found that within the range of 44~300 mm from the meniscus, the friction between the cast billet and the mold was mainly liquid friction, and the friction stress value increased from 0 to 145 KPa. Within 300–720 mm from the meniscus, the billet shell is in direct contact with the mold. The friction between the cast billet and the mold is mainly solid-state friction, and the friction stress value increases from 10.6 KPa to 26.6 KPa. It indicates that the excessive frictional stress inside the mold causes poor lubrication of the cast billet. By reducing the taper of the mold and optimizing the physical and chemical properties of the protective powder, within the range of 44~550 mm from the meniscus, the friction between the cast billet and the mold is mainly liquid friction, and the friction stress value varies within the range of 0–200 Pa. It reduces the frictional stress inside the mold, improves the lubrication between the billet shell and the mold, and completely solves the problem of mesh cracks on the surface of 40Mn2 steel cast billets. Full article

The development of effective drug delivery systems, in terms of their application route and release profile, is crucial for improving the therapeutic outcomes of all bioactive compounds. In this study, we explored the encapsulation of 5-fluorouracil, a commonly used chemotherapeutic agent, in poly(lactic acid) films for the first time and the role of chitosan particles in the structure, as no previous studies have examined their potential for this purpose. The objective is to enhance the sustained release of 5-FU and minimise the burst release step while leveraging the biocompatibility and biodegradability of these polymers. PLA films were fabricated using a solvent casting method, and 5-FU was encapsulated either directly within the PLA matrix or loaded into chitosan particles, which were then incorporated into the film. The physicochemical properties of the films, including morphology, wettability, phase state of the drug, thermal stability, drug loading efficiency, and release kinetics, were evaluated along with their barrier and mechanical properties. The results indicate a change in morphology after the addition of the drug and/or particles compared to the empty film. Additionally, the strain value at break decreased from nearly 400% to below 15%. Young’s modulus also changes from 292 MPa to above 500 MPa. The addition of chitosan particles lowered the permeability and vapour transmission rate slightly, while dissolving 5-FU increased them to 241 g/m²·24 h and 1.56 × 10⁻¹³ g·mm/m²·24 h·kPa, respectively. Contact angle and surface energy values went from 71° and 34 mJ/m² for pure PLA to below 53° and around 58 mJ/m² for the composite structures, respectively. Drug release tests, conducted for 8 h, indicated a nearly 2-fold decrease in the amount of drug released from the film with particles within this period, from around 45% for bare particles and PLA film to 25% for the combined structure, indicating the potential of this system for sustained release of 5-FU. Full article

Pectin–tomato paste edible films with potential antioxidant activity were studied. Initially, the films were formed by drying at 40 °C in the presence and absence of glycerol. The effect of drying temperature on several physicochemical, mechanical, and optical properties of glycerol films formed after drying at 40, 50, and 60 °C was investigated. Finally, films formed at different drying conditions (namely F40, F50, and F60) sharing the same antioxidant activity (44.28–45.53%) were studied in terms of their surface pH; solubility; folding endurance; antimicrobial, dynamic mechanical, and barrier properties; contact angle; and FT-IR. Their thickness, weight, opacity, strength, stiffness, and antioxidant activity (AA) [a*] increased with increasing tomato paste content, whereas [L*] decreased. The moisture content was statistically affected by both the presence of glycerol and the drying temperature. AA decreased as drying temperature increased. Overall, the thickness varied from 45 to 182.31 μm, weight from 0.27 to 1.24 g, moisture content from 20.74 to 56.66%, stress from 189 to 959 kPa, Young’s modulus from 86 to 382 kPa, and AA from 16.9 to 53%. In the last step, F60 was less hydrophilic, had a greater density, and better barrier properties, whereas F50 was stiffer and the least strong. Our findings provide information regarding the selection of an optimum drying temperature for pectin-based films with antioxidant properties. Full article

Aflatoxins are toxic organic substances that are synthesized on the surfaces of seeds, nuts, and similar products by some fungi under elevated humidity. They decompose at temperatures well above 130 °C, so standard heating or autoclaving is an obsolete technique for the degradation of toxins on surfaces without significant modification of the treated material. Non-equilibrium plasma was used to degrade aflatoxins at low temperatures and determine the efficiency of O atoms. A commercial mixture of aflatoxins was deposited on smooth substrates, and the solvent was evaporated so that about a 3 nm thick film of dry toxins remained on the substrates. The samples were exposed to low-pressure oxygen plasma sustained by an inductively coupled radiofrequency (RF) discharge in either the E or H mode. The gas pressure was 20 Pa, the forward RF power was between 50 and 700 W, and the O-atom flux was between 1.2 × 10²³ and 1.5 × 10²⁴ m⁻² s⁻¹. Plasma treatment caused the rapid degradation of aflatoxins, whose concentration was deduced from the fluorescence signal at 455 nm upon excitation with a monochromatic source at 365 nm. The degradation was faster at higher discharge powers, but the degradation curves fitted well when plotted against the dose of O atoms. The experiments showed that the aflatoxin concentration dropped below the detection limit of the fluorescence probe after receiving the O-atom dose of just above 10²⁵ m⁻². This dose was achieved within 10 s of treatment in plasma in the H mode, and approximately a minute when plasma was in the E mode. The method provides a low-temperature solution for the efficient detoxification of agricultural products. Full article

Wearable tactile sensors with high sensitivity can be potentially used to continuously monitoring physiological signals that are closely related to disease diagnosis and health condition tracking. However, the development of such tactile sensors involves a number of challenges, including a series of expensive patterning processes for microstructure manufacturing and addressing the large thickness of the microstructured composite film. Herein, a mold-free approach is presented to develop an ultra-thin ZnO/PEDOT:PSS composite film with flower-like microstructures via a feasible solution process for highly sensitive tactile sensors. The fabricated tactile sensors exhibit a high sensitivity of 4 × 10³ kPa⁻¹ in the pressure range 0–10 kPa, a fast response to various pressures in merits of the hierarchical microstructures on top of the ultra-thin composite films. Thanks to the fascinating performance of the devices, the tactile sensors are demonstrated with the ability to monitor physiological signals, subtle human body motions, and spatial pressure distribution. Full article

Carboxymethyl chitosan (CMCS) exhibits excellent film-forming capability but suffers from limited water resistance. To enhance hydrophobicity and antimicrobial properties, citrus essential oil was emulsified directly with citrus pectin and dispersed into the CMCS matrix. This study investigated the effects of varying emulsion concentrations (0, 1, 3, 5, and 7 wt%) on film performance. FT-IR, XRD, and SEM analyses confirmed uniform emulsion distribution within the CMCS matrix with favorable compatibility. Increased emulsion loading improved water resistance, antioxidant activity, and antimicrobial efficacy of the CMCS-based films, with the 3% emulsion concentration achieving optimal mechanical strength (TS: 4.09 MPa, EAB: 144.47%) and water vapor permeability (1.30 × 10⁻¹⁰ g·m·(Pa·s·m²)⁻¹). Applied to grape preservation, the films significantly delayed quality deterioration of grapes. Furthermore, by modulating the activity of enzymes involved in anthocyanin metabolism, the films could effectively extend the shelf life of grapes by suppressing the oxidative degradation of anthocyanins. Full article

This study develops a sustainable biopolymer film derived from potato peel waste (PW), enhanced with low- and high-viscosity sodium alginate (SA) through a solution casting method. The effect of calcium chloride crosslinking on the PW/SA composites was also evaluated. Scanning electron microscopy (SEM) analysis revealed that SA incorporation improved the film’s cohesion and uniformity, with both low- and high-viscosity SA showing nearly similar effects. Both the addition of SA and crosslinking led to enhanced tensile strength, as well as improved moisture barrier properties, by lowering the water vapor permeability (WVP) factor. The inclusion of high-viscosity SA (hvSA) resulted in superior mechanical and moisture barrier properties compared to the low-viscosity SA (lvSA), achieving a tensile strength of 5.34 MPa, with a 68% improvement compared to the pure PW film. The WVP analysis showed that hvSA had a superior impact, leading to a 32% reduction in WVP compared to the pure film. Crosslinking further boosted the tensile strength and moisture barrier properties. The crosslinked hvSA/PW composite shows the highest tensile strength among all samples, measuring 6.47 MPa, which accounts for a 104% enhancement compared to the pure film. It also led to a 34% reduction in WVP, reaching a value of 1.58 × 10⁻¹² g/(Pa·cm·s). The findings demonstrate that PW/SA composites, especially the crosslinked hvSA/PW, offer the highest mechanical and barrier properties, making them suitable for biodegradable packaging and biomedical applications. Full article

Blackseed oil supplemented with caseinate (CA)–carboxymethyl chitosan (CMCH) composite membranes were evaluated for their functional properties and as edible coating for extending the shelf life of grape tomatoes. Composite films were prepared from equal parts of (CaCa or NaCa) and (CMCH) with or without supplemented 3% blackseed oil (BO) and evaluated for their functional properties. Subsequently, the edible membrane coating was evaluated to extend the shelf life of grape tomatoes (Solanum lycopersicum L.). The water vapor permeability (WVP) of the films was the lowest for the calcium caseinate–carboxymethyl chitosan–blackseed oil (CaCa-CMCH-BO) film (3.01 g kPa⁻¹ h⁻¹ m⁻²). Adding blackseed oil to the edible film matrix also led to a significant increase in its mechanical properties, resulting in tensile strength values of 12.5 MPa and 10.2 MPa and elongation at break values of 90.5% and 100% for NaCa-CMCH-BO and CaCa-CMCH-BO, respectively. The composite films also exhibited good compatibility through hydrogen bonding and hydrophobic interactions, as confirmed by FTIR spectroscopy. The particle size and zeta potential of CaCa-CMCM-BO were 117 nm and −40.73 mV, respectively, while for NaCa-CMCH-BO, they were 294.70 nm and −25.10 mV, respectively. The incorporation of BO into the films resulted in greater antioxidant activity. When applied as an edible film membrane on grape tomatoes, the coating effectively delayed the deterioration of tomatoes by reducing weight loss, microbial spoilage, and oxidative degradation. Compared to the control, the coated fruits had delayed ripening, with a shelf life of up to 30 days, and reduced microbial growth over the entire storage period. Full article