Using “intercalation bridging” to effectively improve the electrothermal properties of sheet graphite / ultrafine carbon powder conductive paste for screen printing

Electrothermal materials can easily and controllably convert electric energy into heat energy, and are widely used in many electrothermal fields. In this paper, a series of conductive pastes were simply prepared by ball milling, and their rheological and electrothermal properties were studied. Phenolic resin was used as curing agent of epoxy resin and rheological modifier, which could make the paste have very good printing applicability. Ultrafine carbon(UC) powder has excellent dispersion effect. Sheet carbon materials such as graphite powder(GP), graphite nanosheet(GS) and graphene(GE) would improve the performance of paste using only UC as conductive filler. It was proved that GE with the smallest thickness has the most obvious lifting effect. UC was gathered around the graphene sheet, as a bridge between graphene sheets. GE could also be connected with each other to build a more effective and denser conductive path. The electrothermal film could reach 199°C under 30 V voltage, increasing by 254.7% compared with the electrothermal film with only UC as conductive filler. The electrothermal film had a short response time, good recyclability and excellent flexibility. The electrothermal film also had certain electromagnetic shielding efficiency. The electromagnetic shielding efficiency SE could reach about 20 dB at 30–1500 MHz, and the ratio of field strength before and after attenuation SE_% could reach 97%?+?. This electrothermal film has simple preparation process, good printing applicability, controllable film resistance, excellent flexibility, fast response speed and good recyclability. It is suitable for large-scale preparation and has broad application prospects in many scenarios.

     

Ni2P(O)–Fe2P(O)/CeOx as high effective bifunctional catalyst for overall water splitting

The development of cost-effective bifunctional catalysts with excellent performance and good stability is of great significance for overall water splitting. In this work, NiFe layered double hydroxides (LDHs) nanosheets are prepared on nickel foam by hydrothermal method, and then Ni₂P(O)–Fe₂P(O)/CeO_x nanosheets are in situ synthesized by electrodeposition and phosphating on NiFe LDHs. The obtained self-supporting Ni₂P(O)–Fe₂P(O)/CeO_x exhibit excellent catalytic performances in alkaline solution due to more active sites and fast electron transport. When the current density is 10 mA cm^?2, the overpotential of hydrogen evolution reaction and oxygen evolution reaction are 75 mV and 268 mV, respectively. In addition, driven by two Ni₂P(O)–Fe₂P(O)/CeO_x electrodes, the alkaline battery can reach 1.45 V at 10 mA cm^?2.     

Exploring the activation mechanism of alcalase activity with pulsed electric field treatment: Effects on enzyme activity,spatial conformation,molecular dynamics simulation and molecular docking parameters

This study used alcalase derived from Bacillus licheniformis as the research object. We revealed the mechanism by which pulsed electric field (PEF) treatment increases alcalase activity. Alcalase is widely used in the food and brewing industries. The results showed that alcalase activity was increased by 11.26%, α-helix structure was reduced by 18.80%, and the number of hydrogen bonds in the molecule also was decreased from 309 to 305 at 10 kV/cm, which showed that the partial unfolding of the secondary structure was an important factor leading to an increase in alcalase activity. In contrast, fluorescence intensity and ζ-potential were reduced by 61.28% and 17.99%, respectively, and the binding energy between alcalase and casein in molecular docking increased by 15.07%, indicating that the tertiary structure was also a key factor in improving activity. Furthermore, molecular docking technology intuitively reflects that PEF treatment increased alcalase activity.     

Highly-hydrophobic nanofiber mat for efficient colonic delivery of lactoferrin: Preparation,characterization and release mechanism

Lactoferrin (Lf) is a bioactive protein with varied biological effects. To improve its anti-digestive stability in oral administration, a novel nanocarrier with high hydrophobicity for colonic delivery of Lf was creatively developed by modified coaxial electrospinning. First, a suitable biocompatible solvent, acetic acid, was screened as the mono-solvent for ES100 electrospinning, creating highly-hydrophobic ES100 nanofiber mat (contact angle = 133.8^o). Then, Lf-loaded W/O emulsion was prepared as the core fluid to ensure the successful coaxial electrospinning and generate Lf encapsulated core/shell nanofiber mat (ES@Lf). Lf was demonstrated maintaining structural integrity and anti-colon cancer activity during encapsulation and oral delivery. In vitro assay indicated 92.3% Lf was sustainably released in colon, and its release followed a complex mechanism in which the erosion was dominant. Instead of pH-dependent erosion, the synergistic action through gut microbiota adhesion and their metabolites, especially short-chain fatty acids, was illustrated for disintegration of ES@Lf nanofiber for the first time.     

Preparation and characterization of Cf/Pollucite composites through geopolymer precursors

Continuous carbon-fibre-reinforced Cs-geopolymer composite (C_f/CsGP) were prepared, and its in-situ conversion was investigated during high-temperature treatments. The effect of treatment temperature on the thermal evolution process and mechanical properties of the resulting products were systematically evaluated. The results indicated that the crystallization temperature of C_f/CsGP composite was considerably delayed because the amorphous structure of carbon fibres was not conducive as a nucleation substrate for pollucite derived from the CsGP matrix. Moreover, the integrity of the corresponding resulting products derived from the C_f/CsGP composite were damaged due to thermal shrinkage that occurred during the high-temperature treatment process. When treatment temperature was ≤1200^oC, the mechanical properties of the corresponding products exhibited an upward trend, which was ascribed to the improvement of the densification degree of the resulting composite and well interface-bonding state between carbon fibres and pollucite. However, the mechanical properties of the resulting composites decreased with the treatment temperature continued increased from 1200 to 1400^oC. This phenomenon was attributed to the impairment of fibre properties caused by interfacial reactions.     

Harvesting Air and Light Energy via “All-in-One” Polymer Cathodes for High-Capacity,Self-Chargeable,and Multimode-Switching Zinc Batteries

Aqueous rechargeable Zinc (Zn)–polymer batteries are promising alternatives to prevalent Li-ion cells in terms of cost, safety, and rate capability but they suffer from limited specific capacity in addition to poor environmental adaptability. Herein, air and light are successfully utilized from external environments in single near-neutral two-electrode Zn batteries to enable remarkably improved electrochemical performance, fast self-charging, and switchable multimode-operation from Zn–polymer to Zn–air cells. This system is enabled by a well-designed polyaniline-nanorod-array based “all-in-one” cathode combining reversible redox capability, oxygen reduction activity, and photothermal-responsiveness. The initiative design allows perfect integration of multiple energy harvesting from ambient “air” and light, energy conversion, and storage in one single cathode. Thus, it can act as an efficient light-assisted electrically-rechargeable Zn–polymer cell featuring the highest specific capacity of 430.0 mAh g⁻¹ among all existing polymer cathodes. Without external power sources, it can be self-charged to deliver a high discharging capacity of 363.1 mAh g⁻¹ by concurrently harvesting chemical energy from air and light energy for only 20 min. It can also switch to a light-responsive Zn–air battery mode to surmount the output capacity limit of Zn–polymer battery mode for continued electricity supply.     

3D-printing of polymer‐derived SiCN ceramic matrix composites by digital light processing

In this study, we present a DLP 3D-printing strategy for the fabrication of SiCN ceramic matrix composites (CMCs). The polysilazane-based preceramic polymer containing inert fillers was UV-cured into a green body and then converted to SiCN CMCs after pyrolysis. The introduced fillers (Si₃N₄ particles and Si₃N₄ whiskers) as reinforcements are well dispersed in the matrix, which can not only effectively reduce the linear shrinkage and weight loss, but also greatly improve the mechanical properties of the SiCN CMCs. The bending strength of the SiCN CMCs reinforced with 10 wt% Si₃N₄ whiskers (without surface polished) reached 180.7 ± 15.6 MPa. Furthermore, the effect of fillers content on microstructure and porosity of the SiCN CMCs are discussed, and it was found that the excessive fillers led to increased pore defects and decreased continuity of the matrix, thereby reducing the mechanical properties of the SiCN CMCs. This strategy provides a promising ceramic manufacturing technique to fabricate polymer‐derived CMCs with complex-shaped and high-performance for potential demanding applications.     

红心火龙果发酵液喷雾干燥工艺优化及红心火龙果籽油的研究

以红心火龙果发酵液作为研究对象,通过优化喷雾干燥工艺制备粉剂,最佳工艺条件为:20%麦芽糊精,进液量:10mL/min,进口温度为120℃,出口温度为65℃;得到的粉剂为紫红色粉末,益生菌含量达到108cfu/g以上,口感酸甜。将发酵后的火龙果籽进行提取,得到的火龙果籽油含有丰富的十六酸、亚油酸和油酸。     

Design and synthesis of side-chain optimized poly(2,6-dimethyl-1,4-phenylene oxide)-g-poly(styrene sulfonic acid) as proton exchange membrane for fuel cell applications: Balancing the water-resistance and the sulfonation degree

Side-chain optimized poly (2,6-dimethyl-1,4-phenylene oxide)-g-poly (styrene sulfonic acid) (PPO-g-PSSA) is designed with balanced water-resistance and sulfonation degree. The PPO-g-PSSA is synthesized by controlled atom-transfer radical polymerization (ATRP) from brominated poly (2,6-dimethyl-1,4-phenylene oxide) (PPO-xBr) and ethyl styrene-4-sulfonate and followed by hydrolysis. A series of PPO-g-PSSA are prepared possessing different bromination degree (x) of PPO-xBr and polymerization degree (m) of the side-chains and the water-resistances of the fabricated membranes are investigated. The results show that a PPO-g-PSSA at relatively low x (x < 0.2) and high m (m > 4) exhibits good balance between the water-resistance and the sulfonation degree. Namely, it displays suitable proton conductivity with compromised water-resistance. Moreover, a maximum ion exchange capacity (IEC) of 3.24 mmol g^?1 is reached without the sacrifice of water-resistance. In addition, PPO-g-0.08PSSA-13 and PPO-g-0.14PSSA-4 are chosen characterized by thermogravimetric analysis, proton conductivities and mechanical properties. At 90% RH, the optimized PPO-g-0.08PPSA-13 possesses a proton conductivity of 37.9 mS cm^?1 at 40 °C and 45.5 mS cm^?1 at 95 °C, respectively.