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Polylactic acid (PLA)/nano-TiO2(TiO2 NPs)/Graphene oxide (GO) nano-fibrous films were prepared by ultrasonic assisted electrostatic spinning technology, and the effects of TiO2 NPs:GO mass ratio and ultrasonic power on film morphology and mechanical, thermal, barrier and antibacterial properties were investigated. The addition of TiO2 NPs and GO can significantly increase the tensile strength and elongation at the break of PLA nano-fibrous films, and improve the water barrier properties of the nano-fibrous films. The antibacterial experiment showed that the inhibition rates of the nano-fibrous films against Escherichia coli and Staphylococcus aureus after 24 h exposure to UV irradiation reached 94.4 ± 1.8% and 92.6 ± 1.7% At the same time, the fresh-keeping packaging experiment of green peppers at room temperature, through the determination of hardness, soluble solids, chlorophyll content to determine the degree of decay of green pepper, it showed that PLA/TiO2 NPs/GO nano-fibrous films can better maintain the sensory quality of green peppers, delay the rate of spoilage of green peppers, and prolong the preservation period of green peppers.

In this study, chitosan/halloysite nanotubes/tea polyphenol (CS/HNTs/TP) nanocomposite films were prepared by the solution casting method. The scanning electron microscopy (SEM) result showed that the nanocomposite film with a CS/HNTs ratio of 6:4 and a TP content of 10% (C6H4-TP10) had a relatively smooth surface and a dense internal structure. The water vapor barrier property of the nanocomposite film was improved due to the tortuous channels formed by the HNTs. However, the swelling degree and water solubility of the nanocomposite films were decreased. The nanocomposite films have a good antioxidant capacity. Antibacterial experiments showed that the C6H4-TP10 nanocomposite film had certain inhibitory effects on the growth of both E. coli and S. aureus. In addition, we used 3D printer to verify the printability of the optimal formulation of the film-forming solution. Overall, this strategy provides a simple approach to construct promising natural antioxidants and antibacterial food packaging.

Encapsulation effectively delays the volatilization of lemon essential oil (LEO). Here, various chitosan (CS)-LEO nanoparticles were prepared by emulsification using different CS and Tween-80 concentrations and CS:TPP and CS:LEO ratios. The CS-LEO nanoparticles were spherical, small in size (58 ± 9 nm), had a low polydispersity index (0.15), and were highly stable under the right conditions. FTIR spectra indicated that they were fully encapsulated in the films. The composite films are characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscope (SEM) and X-ray diffraction (XRD). Relative to grass carp collagen (GCC) films, edible GCC/CS-LEO had lower oxygen permeability (OP), higher tensile strength (TS), and higher elongation at break (EB). The LEO release rate increased with decreasing GCC:CS-LEO ratio. At GCC:CS-LEO ratio = 7:3, a maximum LEO release rate of 83.6 ± 9.7% was achieved over 15 days. GCC/CS-LEO films can effectively inhibit lipid oxidation, prevent microbial proliferation, and delay the deterioration of pork at 4 °C for 21 days.

This paper presents a comprehensive investigation of the effects of cutting parameters on the surface integrity of milled γ-TiAl alloys. Surface topography, surface roughness, surface defects, plastic deformation, micro-hardness, chip morphology, and tool wear of the milled γ-TiAl alloys were analyzed. The results indicate that the feed rate had the greatest influence on the surface topography and surface roughness. The value of surface roughness increased with the increase in cutting depth and feed rate. However, with the increase in cutting speed, it initially increased and then decreased. The minimum surface roughness was found to be 0.066 μm. The thickness of the plastic deformation layer and the micro-hardness value increased with the increase in cutting depth and feed rate. Also, they initially increased and then decreased with the increase in cutting speed. The minimum thickness of the plastic deformation layer was 15 μm and the depth of the hardened layer on the processed surface varied between 55 and 70 μm. The chip morphology was closely related to the quality of the processed surface. When the cutting depth and feed rate decreased, the chip morphology was transformed from segmented to nearly smooth. When the cutting depth and feed rate reached a critical point, plastic processing of γ-TiAl was achieved. Compared to brittle deformation, a more favorable processed surface was obtained. Finally, the comparison tests of tool wear were carried out with dry and flood coolant cutting. When the cutting speed reached 120 m/min in dry cutting, the tool life was very poor, and the cutting distance was only 1 m. However, the tool life was generally good when cutting with low cutting speed under the following conditions: vc = 60 m/min, ap = 0.1 mm, and fz = 0.01 mm/tooth. Under these conditions, the cutting distance was 60 m in dry cutting with the tool wear of 0.2 mm and 120 m in flood coolant cutting with the tool wear of 0.1 mm. The tool life in flood coolant operation was better than that of dry operation. The tool life decreased to 30 m when cutting with high cutting speed or feed rate (ap = 0.25 mm or fz = 0.025 mm/tooth).

Expired fruits have always been treated as garbage. In this paper, expired passion fruit shells are processed into carbon quantum dots (CQDs) by hydrothermal synthesis method. Expired passion fruit shells based carbon quantum dots were characterized using TEM-EDS, FTIR, PL, XRD, XPS, Raman spectrum and Uv–vis analysis. The morphology of CQDs shows sphere shape with the size below 5 nm. CQDs exhibit a weak graphite phase structure according to Raman spectrum. The photoluminescence of CQDs shows the obvious excitation-dependent property with the quantum yield of 1.8%. In addition, expired passion fruit pulp was treated using hydrothermal method. The final product was analyzed using TEM and GC–MS. The result shows the high content of furandione in the product, which indicates the potential for further extraction by purification. This paper expands new way for the reuse of expired fruits.

Magnetoresistance effects are used in a variety of devices including hard disk drives and magnetic random access memories. In particular, giant magnetoresistance and tunnelling magnetoresistance can be used to create spin valves and tunnel junctions in which the resistance depends on the relative magnetization orientations of two ferromagnetic conducting layers. Here, we report a magnetoresistance effect that occurs in a platinum layer deposited on a magnon junction consisting of two insulating magnetic yttrium iron garnet (YIG) layers separated by an antiferromagnetic nickel oxide spacer layer. The resistance of the platinum layer is found to depend on the magnetization of the YIG layer in direct contact with it (an effect known as spin Hall magnetoresistance), but also the magnetization of the adjacent YIG layer in the junction. The resistance of the platinum layer is higher when the two YIG layers are aligned antiparallel than when parallel. We assign this behaviour to a magnonic nonlocal spin Hall magnetoresistance in which spin-carrying magnon propagation across the junction affects spin accumulation at the metal interface and hence modulates the spin Hall magnetoresistance. The effect could be used to develop spintronic and magnonic devices that have spin transport properties controlled by an all-insulating magnon junction and are thus free from Joule heating. A magnetoresistance effect that occurs in a platinum layer deposited on a magnon junction consisting of two insulating magnetic yttrium iron garnet layers separated by an antiferromagnetic nickel oxide spacer layer could be used to create spintronic and magnonic devices that are free from Joule heating.

In this study, a coaxial electrospray process was used to produce nanoparticles, in which thymol was encapsulated in a core–shell of zein and shellac. We then investigated fluid velocity and solution concentrations on the electrospray. Scanning electron microscopy revealed that the thymol/zein/shellac particles prepared at a flow rate ratio of 0.6:0.3 mL/h were rounder with smaller diameters. The highest encapsulation efficiency of thymol was 81.34%, the average particle size was 606.53 nm, and the retention rate of thymol was 68.74% after 30 days. Moreover, we investigated the thermal stability, antimicrobial activity, and simulated gastrointestinal release curves of the nanoparticles. Finally, the nanoparticles were used as a coating for fresh-cut cantaloupe. Compared with the blank nanoparticle control group, the coating significantly extended the shelf life of cantaloupe to 16 days. Our results indicate that these nanoparticles have great potential for application in food preservation.

WC-Co cemented carbide tools offer better cutting performance when cutting difficult-to-machine materials, such as high-temperature alloys, titanium alloys, and high-strength steels. In this paper, high performance WC-8 wt.% Co cemented carbide materials with cBN and VC were prepared by spark plasma sintering. The effects of cBN and VC content on mechanical properties and microstructure of WC-8 wt.% Co-VC-cBN cemented carbide materials were studied. The results show that the relative density, Vickers hardness, and fracture toughness of WC-based cemented carbide materials decreased significantly as the content of cBN and VC increased. WC-8 wt.% Co-0.2 wt%VC-1 wt.% cBN (named as YG8V2B10) cemented carbide material had the optimal properties when sintered at 1250 °C. Its Vickers hardness, fracture toughness, and flexural strength are 20.81 GPa, 13.01 MPa m1/2, and 1630 MPa, respectively. High-temperature flexural strength of YG8V2B10 was also investigated. The flexural strength of YG8V2B10 cemented carbide materials decreased as the temperature increased. When the temperature of YG8V2B10 cemented carbide material exceeded 400 °C in air, matrix at the surface of YG8V2B10 was oxidized, which leads to a significant decrease in the flexural strength.

International audience; Customization of food using the three-dimensional (3D) printing technique is an extremely convenient and healthy way to cook food with maximum utilization of materials, and consequently, this technique has received considerable attention from the public in recent years. In this study, we explored the effect of material composition on the quality of 3D-printed food using wheat flour, freeze-dried mango powder, olive oil and water. Results showed that without adding the freeze-dried mango powder and olive oil, the best printing quality was obtained with a flour-to-water ratio of 5:3. When 2% of the total mass of olive oil was added, the best printing quality was obtained for a flour:water:olive oil ratio of 55:2.75:30. The optimum compressive pressure, needle velocity, needle diameter and internal filling ratio yielding the best printing quality were 600 kPa, 6 mm/s, 0.58mm and 50%, respectively. The food samples produced using these optimum parameters exhibited multiple merits including well-organized packing structure, clear internal texture profile and a smaller total deformation.

International audience; In this study, polyvinyl alcohol (PVA) was used as a film-forming substrate, added to extracted tea polyphenols (TPs) in various ratios and processed with ultrasonication to form films using the tape-casting method. The effects of ultrasonic processing duration on the properties of PVA/TP antibacterial active materials were explored via material property testing. The results showed that, overall, ultrasonic processing degraded the tensile strength and elongation at break of the composite films. When PVA/TP composite films with a PVA-to-TP mass ratio of 8:2 were processed with ultrasonication for 30 min, the swelling capacity was (740.19 +/- 64.67)% and solubility was (5.26 +/- 1.31)%. Ultrasonication also improved the degradability and barrier properties of composite films. Moreover, 8/2 composite films with the PVA/TP ratio of 8:2 exhibited excellent bacteriostatic properties; after ultrasonication processing, the films had a bacteriostatic rate of (95.5 +/- 4.2)% and (91.8 +/- 3.7)% against Staphylococcus aureus and Escherichia coli, respectively, making them suitable for use as antibacterial active materials in food packaging.

Polyacrylonitrile (PAN)/β-cyclodextrin (β-CD) composite nanofibrous membranes immobilized with nano-titanium dioxide (TiO2) and graphene oxide (GO) were prepared by electrospinning and ultrasonic-assisted electrospinning. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) confirmed that TiO2 and GO were more evenly dispersed on the surface and inside of the nanofibers after 45 min of ultrasonic treatment. Adding TiO2 and GO reduced the fiber diameter; the minimum fiber diameter was 84.66 ± 40.58 nm when the mass ratio of TiO2-to-GO was 8:2 (PAN/β-CD nanofibrous membranes was 191.10 ± 45.66 nm). Using the anionic dye methyl orange (MO) and the cationic dye methylene blue (MB) as pollutant models, the photocatalytic activity of the nanofibrous membrane under natural sunlight was evaluated. It was found that PAN/β-CD/TiO2/GO composite nanofibrous membrane with an 8:2 mass ratio of TiO2-to-GO exhibited the best degradation efficiency for the dyes. The degradation efficiency for MB and MO were 93.52 ± 1.83% and 90.92 ± 1.52%, respectively. Meanwhile, the PAN/β-CD/TiO2/GO composite nanofibrous membrane also displayed good antibacterial properties and the degradation efficiency for MB and MO remained above 80% after 3 cycles. In general, the PAN/β-CD/TiO2/GO nanofibrous membrane is eco-friendly, reusable, and has great potential for the removal of dyes from industrial wastewaters.

Ultrasonication-assisted solution casting was used to prepare polyvinyl alcohol (PVA)/sodium carboxymethyl cellulose (CMC)/nano-ZnO/multilayer graphene nanoplatelet (xGnP) composite films, the performances (mechanical properties, water vapor permeability (WVP), biodegradability and antibacterial activity) of these films were investigated as a function of the ZnO NPs:xGnP mass ratio and ultrasonication time. Intermolecular interactions among ZnO NPs, xGnP and the PVA/CMC matrix were shown to improve WVP, while X-ray diffraction and scanning electron microscopy analyses revealed that the internal reticular structure of ultrasound-treated PVA/CMC/ZnO NPs/xGnP composite films was in a fluffier state than that of the untreated composite films and the PVA/CMC film. The incorporation of ZnO NPs and xGnP into the composite film reduced its tensile strength and elongation at break, and increased antibacterial activity and biodegradability. In addition, we carried out the experiment of strawberry preservation and measured weight loss ratio, firmness, content of total soluble solids and titration acid. Finally, the composite film of 7:3 had the best preservation effect on strawberries. Thus, the obtained results paved the way to develop novel biodegradable composite films with antimicrobial activity for a wide range of applications.

In this study, we prepared corn starch (CS) and papaya polysaccharide (PPs) films using the solution casting technique. A Box-Behnken experimental design was used to determine the effect of ethanol concentration, extraction duration, and material concentration during PPs extraction. The resulting films were characterized in terms of structural changes, physical, optical, mechanical, Fourier-transform infrared (FTIR) spectroscopy, and thermal properties. The results show that PPs-CS composite films have good antioxidant and moisturizing properties and general antibacterial performance. These results revealed that after adding PPs, the films exhibited a significant increase in swelling and tensile strength, while depicted a reduction in thickness, transparency, and solubility. SEM images revealed that PPs and CS are highly compatible; moreover, FTIR spectroscopy showed that intermolecular hydrogen bonding existed between CS and PPs, forming a compact film structure. Finally, the incorporation of PPs and CS influenced the shelf-life of fresh cut apples, with the edible film incorporated with PPs positively improving sensory acceptance of combined materials.

High frequency magnetic precessions with strong intensity are strongly desired in material systems for high performance magnetic memory or nano-oscillator applications with ultrafast manipulation speed. Here, we demonstrate an exchange-coupled asymmetric composite film structure of Ta/Pd/[Pd/Co]5/Cu(tCu)/[Co/Ni]5/Ta with adjustable strong perpendicular magnetic anisotropy and interlayer coupling strength, in which the dynamic magnetic properties are systematically studied by using time-resolved magneto-optical Kerr effect spectroscopy. It is demonstrated that the in-phase precession frequency is between those of the single hard magnetic [Pd/Co]5 and soft [Co/Ni]5 multilayers, which can be significantly enhanced for the strongly coupled case at tCu < 1 nm. Moreover, in the weakly coupled samples with tCu = 1.0–3.0 nm, besides the common in-phase acoustic mode, an out-of-phase optical mode occurs simultaneously with a frequency even higher than that of the hard magnetic [Pd/Co]5 layer. The optical mode precession frequency and amplitude show an unusual non-monotonic variation trend with the increase of tCu, which has been theoretically analyzed and attributed to the co-effect of decreased coupling strength and increased magnetic anisotropy field difference between the two multilayer stacks. Moreover, by adjusting tCu and the [Co/Ni] repetition number N, an optical mode of strong intensity can be actively achieved, even reaching 80% as compared to the acoustic mode. These results provide effective control and better understanding of magnetic dynamics in perpendicular composite films, which are of key importance for developing ultrafast spintronics-based devices.

Understanding spin dynamics in perpendicular exchange coupled ferrimagnetic materials is an issue of crucial importance for progress in information processing and recording technology. In this paper, the Landau-Lifshitz-Gilbert equation at atomistic-level is employed to model the perpendicular interfacial exchange effect in ferrimagnetic FeGd/FeTb soft/hard bilayer structures. Three types of magnetization switching features are identified by tuning the interfacial exchange strength to be weak coupling, partial coupling, and strong coupling. These features have been further verified by the dynamical simulations, showing the switched soft layer could also help the hard layer magnetization switching. Based on the coercivity difference of the soft layer and hard layer, the left- or right-shift perpendicular exchange bias effect has been theoretically modelled.

In this study, chitosan (CH), mulberry anthocyanin (MA), and lemongrass essential oils (LEO) were used as an interlayer using a 3D printer. Further, cassava starch (CS) was used as a protective layer to form indicator films. The indicator films containing LEO showed significant antioxidant and antibacterial properties, and the release rate of LEO increased with a rise in pH. When chilled pork spoiled, the color of the indicator films changed from red to gray-blue, and the RGB values could be automatically analyzed by a smartphone application to determine pork freshness. These films hold implications as easy-to-use indicators of meat freshness, with great potential for monitoring food spoilage, as part of an intelligent packaging system.

Gelatin is an important biopolymer that is extracted from collagen and is extensively used in the food industry because of its excellent functional properties. However, native gelatin films are moisture-sensitive and readily dissolve, swell, or split when they come in contact with water, which limits its use in food packaging. Various natural and synthetic materials are incorporated in gelatin films to improve their mechanical and thermal stability, elasticity, flexibility, and oxygen and light barrier properties. This review discusses various methods used for gelatin-based film production and modification approaches for improving their functional properties, including mechanical strength, thermal stability, water and light barrier ability, solubility and swelling, and antimicrobial properties. Moreover, gelatin-based films extend the shelf life of stored products due to their antioxidant and anti-microbial properties. The potential applications, challenges, and limitations of gelatin-based films in food packaging are also discussed. However, further research is required to prolong the modification of gelatin-based films using naturally available edible materials that are not commercially utilized. Further, studies about possible health hazards associated with the continuous use of gelatin-based packaging films should also be conducted in the future.

In this study, we prepared a composite of chitosan (CS), halloysite nanotubes (HNTs), and tea polyphenols (TP) using 3D printing technology. The intermolecular interactions between the components and the printability of the ink were analyzed via Fourier transform infrared (FTIR) spectroscopy and rheological properties. The prepared CS/HNTs-TP composite container exhibited high fidelity and precision. The effects of printing parameters, such as nozzle diameter, air pressure, nozzle height, printing speed, and layer height, on the precision of printed CS/HNTs-TP composite containers were examined. The optimal parameters for printing 3D constructs were found to be 0.8-mm nozzle diameter, 0.4-MPa air pressure, 0.5-mm nozzle height, 30-mm/s printing speed, and 0.3-mm layer height, matching the target model with fine resolution, smooth surface texture, and high precision. The printed CS/HNTs-TP composite container was used for storing blueberries. After 12 days of storage, the blueberries preserved in the CS/HNTs-TP composite maintained a 41.87% weight loss ratio, a 59% decay rate, 9.1% total soluble solids (TSS), 4.1 N firmness, 0.43% titratable acidity (TA), and 14.27% ascorbic acid when compared with those of the control group and CS group. The results indicate that CS/ HNTs-TP composites are highly effective in maintaining the quality of blueberries.

In this study, blended films from poly(vinyl alcohol) (PVA) containing chitosan (CS) were prepared via a simple solution casting and electrospraying method. The structures of the PVA-CS films were characterized by Fourier-transform infrared spectroscopy. The morphologies of the films were observed by scanning electron microscopy. The thermal properties of the PVA-CS films were examined by thermogravimetry. The effects of CS contents on the mechanical properties, oxygen permeability values, water vapor permeation levels, and antibacterial behaviors against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) strains were investigated. Compared to the pure PVA film, the PVA-CS films showed greater elongation at break, lower oxygen permeability, higher water barrier properties, and greater antibacterial activity, especially for the PVA:CS weight ratio of 75:25. The obtained results indicate the PVA-CS film may be a promising material for food packaging applications.

At present, common methods for preparing adsorbents for arsenic removal include electrospinning, tape-casting, and the powder method, but there is still a lack of research on the differences in the adsorption properties of arsenic-removal adsorbents prepared by these three methods. In this study, nine composite adsorbents were prepared by electrospinning, tape-casting, and the powder method with ferric hydroxide as the dopant, and their properties were examined. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction confirmed the existence of ferric hydroxide on the surfaces and insides of the composite adsorbents. Differential scanning calorimetry and mechanical performance tests showed that the addition of FeOOH changed the thermal and mechanical properties of the adsorbents. The arsenic(III) adsorption capacity of each composite adsorbent was also determined as well as the effects of pH and temperature. The results showed that polyacrylonitrile/ferric hydroxide (fiber) had the highest arsenic(III) adsorption capacity (11.31 mg/g) under the baseline conditions. When the pH was adjusted to approximately 9, the maximum adsorption capacity increased to 12.41 mg/g. When the control temperature was 15 °C, the maximum adsorption capacity was 12.07 mg/g. After three adsorption cycles, the arsenic(III) removal rate of each composite membrane reached 90%. Overall, the electrospun membranes had the highest adsorption efficiencies among the three types of adsorbents with respect to arsenic removal, and polyacrylonitrile proved to be the best base material. In comparison, polyvinylidene fluoride proved more suitable for tape-casting films and powder adsorbents.

Polyvinyl alcohol (PVA)/titanium dioxide nanoparticles (TiO2 NPs)/3,3′,4,4′-Benzophenone tetracarboxylic acid (BPTA) antibacterial films were prepared by solvent casting and chemical grafting using PVA as the base material and TiO2 NPs and BPTA as antibacterial materials. Scanning electron microscopy results showed that the distribution of TiO2 NPs inside the polymer matrix was substantially uniform. X-ray diffraction (XRD) and FTIR-ATR spectroscopy were used to demonstrate the successful embedding of NPs and the formation of ester bonds in the grafting process, respectively. In the antibacterial experiment, the PVA/1%TiO2 NPs/BPTA film exhibited higher antibacterial activity than other films. Compared with the control group, the surviving population of S. aureus and E. coli decreased by 99.62 ± 0.38% and 98.27 ± 1.47%, respectively. The mechanism of reactive oxygen species (ROS) production was discussed, and the amount of ROS produced by the composite films under light and dark conditions was quantitatively measured. A cycling experiment after quenching ROS showed that the PVA/1%TiO2 NPs/BPTA composite film retained 81.01% and 66.12% of the original charging capacity of the OH• radical and H2O2 after seven cycles. In terms of biodegradability, the degradation performance of the PVA/TiO2 NPs/BPTA composite film was stronger than that of the pure PVA film. Thus, the PVA/TiO2 NPs/BPTA film is considered a promising antibacterial material with superior characteristics of structural stability, reusability, and functionality under both light and dark conditions.

Challenges remain in engineering cardiac tissues with functional and morphological properties similar to those of native myocardium. In the current study, micropatterned fibrous mats are obtained by deposition of electrospun fibers on lithographic collectors to reproduce the anisotropic structure of myocardium, and carbon nanotubes are included in fibers to provide conductivities at the same level of cardiac muscles. The patterned mats are assembled layer-by-layer into patterned scaffolds for coculture of primary cardiomyocytes (CMs) with cardiac fibroblasts (CFs) and endothelial cells (ECs). CMs are organized along the fibers with clear cardiac strips of sarcomeric α-actinin and belt-like connexin-43, showing strong cellular extraction forces and intercellular communications. Compared with square and rectangle patterns, honeycomb (Hc)-patterned scaffolds shows higher ultimate tensile strength and strain to failure. The finite element analysis indicates no apparent stress concentration under stress application in the two orthogonal directions. The Hc-patterned coculture demonstrates significantly higher CM viabilities, deeper penetrations of cells into scaffolds, stronger expression of troponin I, connexin-43 and sarcomeric α-actinin by CMs and more abundant formations of capillary-like networks by ECs than other scaffolds. CMs on Hc-patterned scaffolds display spontaneous beating rates at 101±12times/min after coculture for 5days and remain synchronously beating at 94±8times/min after 15days, which is close to those of adult and neonatal rats. The layered and patterned coculture strategy achieves the spatial arrangement of multiple types of cells and vascularization potential, providing a biomimetic strategy for engineering functional cardiac patches in vitro.

International audience; Active biodegradable packaging films were developed with polyvinyl alcohol (PVA), chitosan (CS) and D-Limonene (DL). The effect of various DL content levels (0%, 2.5%, 5%, 7.5%, and 10% w/w) on the structural, mechanical, biodegradable and antimicrobial properties of PVA/CS films was systematically studied. Good compatibility between DL and PVA/CS, and good dispersion of DL in the PVA/CS matrix were demonstrated by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). PVA/CS films greatly improved their antibacterial, mechanical and barrier properties, which are associated with the considerable biodegradability, after they were incorporated with DL. However, the overloading with DL may weaken hydrogen bonds between polymer chains, resulting in the negative effects on the physical performances of the film. Particularly, the PVA/CS/DL-5% film showed the highest water contact angle and transmittance value, and also showed effective preservations of packaged mango fruits during 10 day of storage at 20 +/- 2 degrees C, based on the characterization by fruits weight loss, decay rate, firmness, titratable acidity, soluble solids, and ascorbic acid. Consequently, DL/PVA/CS composite films may be a promising eco-friendly packaging material for food preservation. (C) 2018 Published by Elsevier B.V.

In this research, chitosan (CS) and poly (vinyl alcohol) (PVA) were adopted as a material, methacryloyloxyethyl trimethyl ammonium chloride (DMC) was added in various concentrations and was treated ultrasonically for the formation of films with the use of the polymer blending method. The influences exerted by the ultrasonication period on PVA/CS/DMC antimicrobial active materials underwent material characteristic tests. The consequences revealed that at the break of the compound films, ultrasonication raised the elongation and tensile strength on the whole. Ultrasonication further or also enhanced the light transmittance performance and composite films&rsquo, barrier property. Furthermore, the compound film with a DMC concentration of 2% had good antibacterial properties, the film&rsquo, s inhibition rates against Staphylococcus aureus and Escherichia coli after ultrasonication were 79.23% &plusmn, 1.92% and 72.31% &plusmn, 1.35%, respectively.

In this study, PLA/TiO2 composites materials were prepared via electrospinning and solution casting processes. By testing the mechanical properties, water contact angle, water vapor permeability, and solubility of the composite nanofibers and films, the comprehensive performances of the two types of nanocomposites were analyzed. The results show that maximum tensile strengths of 2.71 &plusmn, 0.11 MPa and 14.49 &plusmn, 0.13 MPa were achieved for the nanofibers and films at a TiO2 content of 0.75 wt.%. Moreover, the addition of TiO2 significantly cut down the water vapor transmittance rate of the nanofibers and films while significantly improving the water solubility. Further, the antibacterial activity increased under UV-A irradiation for a TiO2 nanoparticle content of 0.75 wt.%, and the nanofiber and films exhibited inhibition zones of 4.86 &plusmn, 0.50 and 3.69 &plusmn, 0.40 mm for E. coli, and 5.98 &plusmn, 0.77 and 4.63 &plusmn, 0.45 mm for S. aureus, respectively. Overall, the performance of the nanofiber was better than that of the film. Nevertheless, both the nanocomposite membranes satisfied the requirements of food packaging materials.

Drying characteristics and quality of apple slices were studied using microwave intermittent drying at different microwave power density (2.2, 3.5, 4.8, and 6.1 W/g), sample thickness (3, 5, 7, and 9 mm) and heating time in each cycle (4, 5, 6, and 7 s). Results showed that the approximate constant rate drying periods and falling rate drying periods were found in all the curves. The drying time decreased with increasing microwave power density and heating time in each cycle, while increased significantly with the growth of sample thickness. Weibull distribution model could fit the drying curves well in all conditions (R² > 0.99) with the scale parameter values changed from 45.88 to 206.08 min and the shape parameters values varied from 1.514 to 1.69. The moisture effective diffusivity calculated by Weibull model ranged from 0.3217 × 10⁻⁹ to 1.435 × 10⁻⁹ m²·s⁻¹. The flavor, texture and overall acceptability values displayed a decreasing tendency with the increase of microwave power density, while increased with the growth of thickness. And the shrinkage rates of apple slices showed a decline tendency with the increase of above parameters. PRACTICAL APPLICATIONS: Apple is a kind of popular and important fruits with high nutrient content, and it has been widely planted in China. Due to its high moisture content, fresh apples will subject to various deteriorative reactions during storage and thus lead to serious post‐harvest losses. Microwave drying technology has been widely used in dehydration of agricultural products in China because of the significant heating efficiency. However, the continuous microwave heating may easily cause the overheating of raw materials and undesirable changes in quality. Microwave intermittent drying (MID) was proposed on the basis of conventional microwave drying and regarded as an efficient processing method by solving the above issues. Currently this technology has been successfully applied to ginkgo fruits, yam and banana slices. Analyzing the effects of drying parameters on MID kinetics and quality of apple slices will have important significance for optimizing the processing efficiency and consumer acceptability of dried products.

The key to addressing the challenges facing cardiac tissue engineering is the integration of physical, chemical, and electrical cues into scaffolds. Aligned and conductive scaffolds have been fabricated as synthetic microenvironments to improve the function of cardiomyocytes. However, up to now, the influence of conductive capability and inner structure of fibrous scaffolds have not been determined on the cardiomyocyte morphologies and beating patterns. In the current study, highly aligned fibers were fabricated with loaded up to 6% of carbon nanotubes (CNTs) to modulate the electrical conductivity, while blend and coaxial electrospinning were utilized to create a bulk distribution of CNTs in fiber matrices and a spatial embedment in fiber cores, respectively. Conductive networks were formed in the fibrous scaffolds after the inoculation of over 3% CNTs, and the increase in the conductivity could maintain the cell viabilities, induce the cell elongation, enhance the production of sarcomeric α-actinin and troponin I, and promote the synchronous beating of cardiomyocytes. Although the conductivity of blend fibers is slightly higher than that of coaxial fibers with the same CNT loadings, the lower exposures to CNTs resulted in higher cell viability, elongation, extracellular matrix secretion and beating rates for cardiomyocytes on coaxial fibers. Taken altogether, core-sheath fibers with loaded 5% of CNTs in the fiber cores facilitated the cardiomyocyte growth with a production of organized contractile proteins and a pulsation frequency close to that of the atrium. It is suggested that electrospun scaffolds that couple conductivity and fibrous structure considerations may provide optimal stimuli to foster cell morphology and functions for myocardial regeneration or establishment of in vitro cardiomyocyte culture platform for drug screening.

Many conductive scaffolds were fabricated to mimic the topography of the cardiac microenvironment in vitro in order to improve the performance of engineered cardiac tissues. This study fabricated aligned poly(lactic-co-glycolic acid)/multiwalled carbon nanotube fibers by electrospinning. The Young's modulus and conductivity were significantly greater on poly(lactic-co-glycolic acid) fibers with 3% multiwalled carbon nanotubes compared to others. Topographical cues and conductivity were applied to investigate the combined effect on cardiomyocyte behavior. Neonatal rat cardiomyocytes cultured on the conductive fibers maintained their viability, induced cell elongation, and enhanced sarcomeric α-actinin and troponin I production in cardiomyocytes. The results indicate that poly(lactic-co-glycolic acid)/multiwalled carbon nanotube composite fibers have great potential for cardiac tissue engineering.

International audience; In this study, biopolymer-based antimicrobial fibrous membranes constituted by polylactic acid (PLA) and ultrasonically dispersed ZnO nanoparticles (NPs) were developed by electrospinning. The morphology, mechanical properties, thermodynamics and antimicrobial properties of membranes with different ZnO NPs content were comprehensively studied. The results showed that the best performance was achieved when the content of ZnO content was 0.5 wt% (PLA/ZnO-0.5%). Specifically, the tensile strength and elongation at break of the composite membrane were 6.85 ± 0.19 MPa and 74.90 ± 0.59%, respectively, and the inhibition zones of Escherichia coli and Staphylococcus aureus were 15.02 ± 0.18 mm and 14.74 ± 0.06 mm, respectively. In addition, an appropriate ultrasonication time of 45 min improved the thermal, ultraviolet (UV) barrier, and antibacterial properties of the composite membrane. At the 45 min ultrasonication time, the inhibition zone of PLA/ZnO-0.5% against Escherichia coli and Staphylococcus aureus was 18.11 ± 0.15 mm and 15.80 ± 0.11 mm, respectively. Therefore, PLA/ZnO-0.5% can be applied in food packaging to provide an antibacterial effect and UV light barrier.

An antibacterial and anti-oxidation composite film was prepared by a casting method using sodium alginate (SA) and apple polyphenols (APPs) as the base material and glycerol as the plasticizer. Silver nanoparticles (AgNPs) were deposited by ultrasonic-assisted electrospray method. The degree of influence of the addition ratio of SA and AgNPs and different ultrasonic time on the mechanical properties, barrier properties, optical properties, and hydrophilicity of the composite film was explored. The composite films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the SA: AgNPs ratio of 7:3 and the ultrasonic time for 30 min have the best comprehensive performance, and SA/AgNPs/APP films showed the lowest water vapor permeability value of 0.75 &times, 10&minus, 11 g/m&middot, s&middot, Pa. The composite film has good strength and softness, with tensile strength (TS) and elongation at break (E) at 23.94 MPa and 29.18%, respectively. SEM images showed that the surface of the composite film was smooth and the AgNPs&rsquo, distribution was uniform. The composite film showed broad antibacterial activity, and the antibacterial activity of Escherichia coli (92.01%) was higher than that of Staphylococcus aureus (91.26%). However, due to the addition of APP, its antioxidant activity can reach 98.39%, which has a synergistic effect on antibacterial activity. For strawberry as a model, the results showed that this composite film can prolong the shelf life of strawberries for about 8 days at 4 &deg, C, effectively maintaining their storage quality. Compared with the commonly used PE(Polyethylene film) film on the market, it has a greater fresh-keeping effect and can be used as an active food packaging material.

Mesenchymal stem cells (MSCs) have been widely used for regenerative therapy. In most current clinical applications, MSCs are delivered by injection but face significant issues with cell viability and penetration into the target tissue due to a limited migration capacity. Some therapies have attempted to improve MSC stability by their encapsulation within biomaterials; however, these treatments still require an enormous number of cells to achieve therapeutic efficacy due to low efficiency. Additionally, while local injection allows for targeted delivery, injections with conventional syringes are highly invasive. Due to the challenges associated with stem cell delivery, a local and minimally invasive approach with high efficiency and improved cell viability is highly desired. In this study, we present a detachable hybrid microneedle depot (d-HMND) for cell delivery. Our system consists of an array of microneedles with an outer poly(lactic-co-glycolic) acid (PLGA) shell and an internal gelatin methacryloyl (GelMA)-MSC mixture (GMM). The GMM was characterized and optimized for cell viability and mechanical strength of the d-HMND required to penetrate mouse skin tissue was also determined. MSC viability and function within the d-HMND was characterized in vitro and the regenerative efficacy of the d-HMND was demonstrated in vivo using a mouse skin wound model.

International audience; Nonvolatile magnetic random-access memory is one of the most promising memory candidates to meet the requirements of high-density and low-power data storage. Downsize scalability and energy efficiency of conventional memory-unit cells with elliptic shape, however, remain matters of great concern. The development of alternative memory-unit-cell architecture that would potentially enhance the performance of practical devices is thus particularly interesting for applications. Here the magnetic configurations for nanoring magnetic tunnel junctions with an in-plane magnetic storage layer are studied by micromagnetic simulation, revealing that, for an appropriate ring width, the outer diameter can be scaled down to less than 20 nm, where the magnetic onion configuration becomes energetically favored. We also study the spin-transfer-torque switching process and dynamic resistance state diagram with respect to the applied magnetic field and spin-polarized current. A low switching-current density is demonstrated. The results indicate the advantage of using nanoring magnetic tunnel junctions as memory units, which may provide an alternative solution for high-storage-density and low-power-consumption nonvolatile memory.

As an advanced manufacturing technology that has been developed in recent years, three-dimensional (3D) printing of macromolecular materials can create complex-shaped components that cannot be realized by traditional processing. However, only a few types of macromolecular materials are suitable for 3D printing: the structure must have a single function, and manufacturing macromolecular functional devices is difficult. In this study, using poly lactic acid (PLA) as a matrix, conductive composites were prepared by adding various contents of multi-walled carbon nanotubes (MWCNTs). The printability and properties of MWCNT/PLA composites with different MWCNT proportions were studied by using the fused deposition modeling (FDM) processing technology of 3D printing. The experimental results showed that high conductivity can be realized in 3D-printed products with a composite material containing 5% MWCNTs, its conductivity was 0.4 &plusmn, 0.2 S/cm, its tensile strength was 78.4 &plusmn, 12.4 MPa, and its elongation at break was 94.4% &plusmn, 14.3%. It had a good melt flow rate and thermal properties, and it enabled smooth printing, thus meeting all the requirements for the 3D printing of consumables.

A sodium alginate/chitosan solution was prepared by dissolving sodium alginate, chitosan, and glycerol in an acetic acid solution. This solution was then combined with a sodium carboxymethyl cellulose solution and the mixture was cast onto a glass plate and dried at a constant temperature of 60 &deg, C. Then, a carboxymethyl cellulose/sodium alginate/chitosan composite film was obtained by immersing the film in a solution of a cross-linking agent, CaCl2, and air-drying the resulting material. First, the most advantageous contents of the three precursors in the casting solution were determined by a completely random design test method. Thereafter, a comprehensive orthogonal experimental design was applied to select the optimal mass ratio of the three precursors. The composite film obtained with sodium alginate, sodium carboxymethyl cellulose, and chitosan contents of 1.5%, 0.5%, and 1.5%, respectively, in the casting solution displayed excellent tensile strength, water vapor transmission rate, and elongation after fracture. Moreover, the presence of chitosan successfully inhibited the growth and reproduction of microorganisms. The composite film exhibited antibacterial rates of 95.7% &plusmn, 5.4% and 93.4% &plusmn, 4.7% against Escherichia coli and Staphylococcus aureus, respectively. Therefore, the composite film is promising for antibacterial food packaging applications.

The identification of a biologic substrate for maintaining hepatocyte functions is essential to provide reliable and predictable models for in vitro drug screening. In the current study, a three-dimensional culture of hepatocytes was established on highly porous fibrous scaffolds with grafted galactose and RGD to afford extensive cell-cell and cell-scaffold interactions spatially. The pore size and ligand densities indicated significant effects on the formation of hepatocyte spheroids in balancing the cell retention, adhesion, and migration on fibrous scaffolds. Fibrous scaffolds with an average pore size of 60 μm and surface grafting densities of galactose at 5.9 nmol/cm(2) and RGD at 6.9 pmol/cm(2) provided optimal microenvironments for hepatocyte infiltration and multicellular spheroid formation. Significant promotions were also demonstrated in the syntheses of albumin and urea and the activities of phase I (CYP 3A11 and CYP 2C9) and phase II enzymes. The in vitro metabolism tests on testosterone and acetaminophen by hepatocytes on the optimal scaffolds indicated the predicated clearance rates of 50.7 and 22.6 ml/min/kg, respectively, which were comparable to the in vivo values of rats. The in vitro hepatotoxicity tests on amiodarone hydrochloride and acetaminophen predicted the half maximal effective concentrations (EC50) to reflect the in vivo toxic plasma concentrations in human. In addition, the enzyme activities, predicted clearance rates and hepatotoxicity values of hepatocytes on the optimal scaffolds experienced sensitive responsiveness to specific inducers or inhibitors of CYP 3A11 and phase II enzymes, exhibiting in vivo-in vitro correlations to a certain extent. These results demonstrate the feasibility of hepatocyte spheroid culture on fibrous scaffolds as an potential in vitro testing model to predict the in vivo drug metabolism, hepatotoxicity, and drug-drug interactions.

Although engineered blood vessels have seen important advances during recent years, proper mechanical strength and vasoactivity remain unsolved problems. In the current study, micropatterned fibrous mats were created to load smooth muscle cells (SMC), and a co-culture with endothelial cells (EC) was established through overlaying on an EC-loaded flat fibrous mat to mimic the layered structure of a blood vessel. A preferential distribution of SMC was determined in the patterned regions throughout the fibrous scaffolds, and aligned fibers in the patterned regions provided topological cues to guide the orientation of SMC with intense actin filaments and extracellular matrix (ECM) production in a circumferential direction. Plasmid DNA encoding basic fibroblast growth factors and vascular endothelial growth factor were integrated into electrospun fibers as biological cues to promote SMC infiltration into fibrous mats, and the viability and ECM production of both EC and SMC. The layered fibrous mats with loaded EC and SMC were wrapped into a cylinder, and engineered vessels were obtained with compact EC and SMC layers after co-culture for 3 months. Randomly oriented ECM productions of EC formed a continuous endothelium covering the entire lumenal surface, and a high alignment of ECM was shown in the circumferential direction of SMC layers. The tensile strength, strain at failure and suture retention strength were higher than those of the human femoral artery, and the burst pressure and radial compliance were in the same range as the human saphenous vein, indicating potential as blood vessel substitutes for transplantation in vivo. Thus, the establishment of topographical cues and biochemical signals in fibrous scaffolds demonstrates advantages in modulating cellular behavior and organization found in complex multicellular tissues.

Cinnamaldehyde (CA) was successfully encapsulated in β-cyclodextrin (β-CD), and polylactic acid (PLA)-based composite fibers were prepared by incorporating CA/β-CD via electrospinning. Morphological, structural, spectral, and antibacterial properties of different weight ratios of PLA:β-CD/CA (88:12, 94:6, 97:3, and 98.5:1.5) and PLA/CA/β-CD fibers were investigated. PLA and CA/β-CD were incorporated by mixing of CA/β-CD inclusions to enhance the viscosity of the mixed solution. The mechanical properties and hydrophilicity of nanofibers were improved following the addition of CA/β-CD. Moreover, CA/β-CD improved the antibacterial activities of the mixture against Escherichia coli and Staphylococcus aureus. PLA/CA/β-CD-3 exhibited excellent antibacterial effects and low cytotoxicity. Thus, our study showed that PLA/CA/β-CD fibers may have applications as wound dressing materials and for use in other biomedical applications.

This paper presents the fabrication of a molecularly imprinted, polymer-based disposable electrochemical sensor for paraoxon (PO) determination. The sensor was based on a screen-printed carbon electrode (SPCE) modified with a surface molecularly imprinted poly (p-aminothiophenol) (PATP)/gold nanoparticles (AuNPs) composite film, which consisted of a PATP outer layer and an AuNPs inner layer. We report a novel strategy, combining surface molecularly imprinting and self-assembly directed electro-polymerization with high densely imprinting PO molecules in the PATP/AuNPs film. Firstly, AuNPs were in situ electrodeposited at the electrode surface, and then assembled with electropolmerizable functional monomer p-aminothiophenol (ATP). Subsequently, PO molecules were assembled onto the ATP monolayer-modified AuNPs, forming a basis of surface molecular imprinting. After that, replenished PO molecules were embedded in the PATP/AuNPs film by PO and the ATP molecular self-assembly directed electro-polymerization in the polymerization precursor mixture. The resulting imprinted PATP/AuNPs/SPCE possesses high sensitivity, affinity, and selectivity toward PO, with a low detection limit of 1 × 10−9 M. The proposed sensor was successfully applied for the determination of PO in fruit and vegetables, giving satisfactory recoveries. The strategy reported herein can be further expected to fabricate various molecular imprinted sensors for the determination of other pesticide residuals.

The spatial arrangement of cardiac myocytes (CMs) and other non-myocytes scaffolds, closely resembling native tissue, is essential to control the CM morphology and function for cardiac tissue regeneration. In the current study, micropatterned fibrous scaffolds were developed to establish a CM co-culture system with cardiac fibroblasts (CFs) and endothelial cells (ECs) as a potential in vitro drug screening model. To pursue a biomimetic approach to influence CM behaviors, strip, oval and wave-patterned mats were constructed by deposition of electrospun fibers on lithographic collectors, followed by precise stacking for cell co-cultures. CMs, CFs, and ECs were located on the patterned scaffolds with controlled cellular distribution in the respective regions and no across condition was found. Compared with those after strip and oval-patterned co-culture, CMs co-cultured on wave-patterned scaffolds displayed significantly greater cell viabilities, larger cell elongation ratios, stronger expressions of cardiac-specific Troponin I, connexin 43 and sarcomeric α-actinin and higher beating rates during 15 days of incubation. The responses of co-cultured CMs to quinidine, erythromycin and sotalol show good correlations with clinical observations in the beating rate and the prolongation of the contraction and relaxation time. The in vivo safety data reflected well with the concentrations for 50% of maximal effect (EC50) after drug treatment on co-cultured CMs, which was determined from the changes in the corrected field potential duration (FPDc) against the drug concentrations. During 15 days of patterned co-culture, the interbeat intervals and fluctuations of the CMs indicated quick changes in response to haloperidol treatment and sufficient restoration of the original beating profiles after drug removal. This study demonstrates the capabilities of micropatterned co-culture of CMs to establish the cardiac function as a reproducible and reliable platform for screening cardiac side effects of drugs.

In this study, gelatin (GEL) extracted from grass carp and tea polyphenols (TP) were encapsulated in chitosan (CS) nanoparticles using an innovative electrospray based ionic gelation method. CS-TP nanoparticles were fully optimized in terms of encapsulation efficiency and polydispersity. The average diameter of the optimal CS-TP nanoparticles was 205 ± 14 nm, and encapsulation efficiency of 66.7% ± 9.9% was achieved. The effects of CS-TP nanoparticles on the physicochemical properties of the GEL/CS-TP composite films were studied. Our results showed that the combination of CS-TP and grass carp gelatin (GEL) can not only weaken the strong interaction between GEL and TP, but also improved the swelling and mechanical properties of GEL. Furthermore, GEL/CS-TP30% composite film showed strong barrier and good mechanical properties, low UV transmission, exhibited high free radical-scavenging ability and prolonged the stability of an easily oxidizable oil for over 14 days, making it a suitable film for use as an edible packaging material. Keywords: Gelatin, Chitosan, Tea polyphenols, Composite films

A major challenge in vascular engineering is the establishment of proper microenvironment to guide the spatial organization, growth, and extracellular matrix (ECM) productions of cells found in blood vessels. In the current study, micropatterned fibrous mats with distinct ridges and grooves of different width were created to load smooth muscle cells (SMCs), which were assembled by stacking on vascular endothelial cell (EC)-loaded flat fibrous mats to mimic the in vivo-like organized structure of blood vessels. SMCs were mainly distributed in the ridges, and aligned fibers in the patterned regions led to the formation of elongated cell bodies, intense actin filaments, and expressions of collagen I and α-smooth muscle actin in a parallel direction with fibers. ECs spread over the flat fibrous mats and expressed collagen IV and laminin with a cobblestone-like feature. A z-stack scanning of fluorescently stained fibrous mats indicated that SMCs effectively infiltrated into fibrous scaffolds at the depth of around 200 μm. Compared with SMCs cultured alone, the coculture with ECs enhanced the proliferation, infiltration, and cytoskeleton elongation of SMCs on patterned fibrous mats. Although the coculture of SMCs made no significant difference in the EC growth, the coculture system on patterned fibrous scaffolds promoted ECM productions of both ECs and SMCs. Thus, this patterned fibrous configuration not only offers a promising technology in the design of tissue engineering scaffolds to construct blood vessels with durable mechanical properties, but also provides a platform for patterned coculture to investigate cell-matrix and cell-cell interactions in highly organized tissues.

An active polyvinyl alcohol (PVA) composite film incorporating pomegranate peel extract (PPE) and sodium dehydroacetate (SD) was prepared by electrospinning. The effects of the ratio of PPE to SD (1:0, 1:0.5, 1:1, 0.5:1, 0:1) in a consistent total mass fraction of ∼5% in the film forming solution were measured in terms of the physical properties, appearance, oxidation resistance, and antibacterial performance of the resulting films. When the ratio of PPE to SD was 1:1, the powder was uniformly dispersed throughout the film, and no obvious aggregation was observed via scanning electron microscopy. The results show that the addition of PPE and SD to PVA film can improve its elongation at break, but has no significant effect on its light transmission or water vapor permeability. Fourier transform infrared spectroscopy indicated that the interaction between PPE, SD, and PVA is complex. The addition of PPE to the film specimens resulted in obvious antioxidant activity. The results of bacteriostatic experiments showed that the antibacterial ability of the film against E. coli and S. aureus increased with increasing PPE and SD. This study thus quantifies the benefits of incorporating PPE and SD into PVA films for potential application as active packaging films or coatings.

We extracted collagen (CL) from the scales of Ctenopharyngodon idella and fabricated a CL self-assembly film. Catalase (CAT) was immobilized on the films using cross-linking, adsorption, and embedding methods. The activity and operational stability of immobilized CAT were investigated, along with the influence of the concentration of glutaraldehyde (GTA) and of the initial concentration of embedded CAT. The results showed that the CL triple helix remained intact. Differential scanning calorimetry data showed that the thermal stability of CL was significantly improved by neutral salt-induced self-aggregation and GTA cross-linking. The immobilized enzyme had high activity and good operational stability. When the enzyme concentration reached 0.5 mg/mL, immobilized enzyme activity of grass carp scales reached a maximum of 2596 U/g, and after twenty-two uses, enzyme activity remained above 50%, and it could be reused >45 times (CAT = 0.5 mg/mL, GTA = 5%, Temperature = 30 °C, pH = 7). Moreover, the optimum temperature and pH of immobilized CAT were 35 °C and 7, respectively, while the same for free CAT was 30 °C and 7, respectively. This indicated that immobilization of CAT has a protective effect.

Nanofibrous composite membranes consisting of polyvinyl alcohol (PVA), graphene oxide (GO), and zinc oxide nanoparticles (ZnO NPs) were prepared by and ultrasonic processing, and electrospinning. The performance of the membranes containing different GO-to-ZnO NP mass ratios was comprehensively investigated in terms of density, mechanical properties, water vapor permeability, optical property, biodegradability and antimicrobial properties. The results showed that an appropriate sonication time (30 min) improved the membrane performance; the composite nanofibrous membrane with a GO-to-ZnO NP mass ratio of 3:7 and 30 min sonication exhibited the best performance with a water vapor permeability of (0.62 ± 0.01) × 10−2 g·h−1 m−2 pa−1, and strain and stress values of 307.84 ± 2.96% and 12.82 ± 0.56 MPa, respectively. Particularly, the UV barrier property of the composite nanofibrous membrane was enhanced. Furthermore, the membrane exhibited strong antibacterial activity against foodborne pathogenic and spoilage bacteria. Thu, it can thus be used as an active food packaging material to ensure the safety of food products and to extend their shelf-life.

We report a comprehensive study of annealing treatment modulation on the laser-induced ultrafast magnetic behaviors in antiferromagnetically exchange-coupled [Ni/Co]4/Ru/[Co/Ni]3 multilayers with perpendicular magnetic anisotropy (PMA). Magnetic hysteresis loops indicate that the uniaxial PMA field Hkeff decreases monotonously with the increase in annealing temperature Ta, but the variation of interlayer coupling field Hex is rather complicated. Time-resolved magnetic-optical Kerr effect (MOKE) measurements demonstrate that the laser-excited demagnetization and precession process relies significantly on Ta. Upon laser impulsion, the MOKE signal immediately shows a nonchanging transient increase and decrease with H increasing for low Ta, but only the ultrafast decreasing behavior for high Ta. From the subsequent dynamic precession spectra, the optical and acoustic precession modes are identified. By fitting the field-dependent frequency curves via the deduced dispersion relations, both Hkeff and Hex are determined and their variation trends agree well with the results from the static magnetic measurement. Moreover, it is found that the critical field where the ultrafast signal decrease occurs is dependent on the co-effect of Hkeff and Hex, whereas the maximum field at which the optical mode precession disappears shares the same trend as Hex. The magnetic damping of acoustic mode is seen to increase with Ta due to the increased inhomogeneities. Our findings provide a deep understanding of the magnetic properties in synthetic antiferromagnetic multilayers with high annealing temperatures, which will be helpful for designing advanced spintronic devices.

Composite films containing different amounts of potassium sorbate (KS) were prepared by using fish scale collagen (Col) and polyvinyl alcohol (PVA). Fourier transform infrared spectroscopy (FTIR), light transmittance, mechanical, water vapor transmission rate (WVTR), and the antibacterial properties of the composite films were analyzed. The results showed that the addition of Col significantly reduced the light transmittance of the composite film, but KS had no significant effect on the light transmission. The tensile strength decreased first and then increased with the addition of KS, while the WVTR increased first and then decreased. The composite film exhibited a certain degree of antibacterial properties against E. coli and S. aureus. In addition, we found that ultrasonic treatment reduced the WVTR, and also improved tensile strength and elongation at break of the composite films, but had no significant effect on other properties. The KS/Col/PVA films have the potential to be used as antimicrobial food packaging.

In this study, we fabricated polyvinyl alcohol (PVA)/chitosan (CS) bilayer films by casting and investigated the effects of preparation conditions and CS content (2, 2.5, or 3 wt.%) on the ability of these films to preserve packaged strawberries. The best performance was achieved at a CS loading of 2.5 wt.% (ultrasound time, 25 min), the strain and stress values were 143.15 &plusmn, 6.43% and 70.67 &plusmn, 0.85 MPa, respectively, oxygen permeability was 0.16 &plusmn, 0.08 cm2&middot, m2&middot, day&minus, 1&middot, MPa&minus, 1, water vapor permeability was 14.93 &plusmn, 4.09 g&middot, cm&minus, s&minus, Pa&minus, 1, and the shelf life of fresh strawberries packaged in the PVA/CS 2.5 wt.% bilayer film was determined to be 21 days at 5 &plusmn, 2 &deg, C and a relative humidity of 60 &plusmn, 5%. Treatment with PVA/CS bilayer films prevented the decrease in the firmness of strawberries during storage (21 days). The evaluated physicochemical parameters (weight loss, decay, firmness, titratable acidity, soluble solid content, ascorbic acid content, and color) indicated that treatment with PVA/CS bilayer films led to better maintenance of the fruit quality. We believe that our study makes a significant contribution to literature because it paves the way to the fabrication of smart packaging materials and facilitates the commercialization of fresh strawberries as an important health food.

Ultrafast demagnetization excited by laser pulses introduces the technological possibility for controlling the magnetic properties of materials on sub-picosecond regime. In this paper, the demagnetization dynamics of amorphous ferrimagnetic TbFeCo alloy is modeled by using the stochastic Landau-Lifshitz-Gilbert equation on an atomistic level. The transition metal (Fe, Co) and rare earth (Tb) atoms are constructed by two different sub-lattice systems. Laser-heating induced demagnetization processes are clearly demonstrated by a series of snapshots. Our simulations show that full demagnetization on the sub-picosecond time scale requires a temperature over the Curie point, and the demagnetization time increases with the Tb content.