Vitrimers have been emerged as a new class of polymers with many attractive properties of material processing such as reshaping, recycling and repairing. Herein, a new type of vitrimers (BDSER) based ...on thermosetting dynamic epoxy network with double disulfide bonds was synthesized by the reaction of a difunctional epoxy monomer containing disulfide bonds with 4,4′-disulfanediyldianiline (4-AFD). Our results demonstrated that the relaxation time of BDSER at 200 °C was as short as 9 s without any catalyst. The storage modulus of BDSER was up to about 2.2 GPa and its glass transition temperature was higher than 130 °C. Additionally, the thermodynamic and chemical properties of BDSER were no significant loss after 3 cycles of continuous breaking/compression molding. Furthermore, the resistance of CNT/PPy/Vitrimer composites (CPV), synthesized by doped BDSER with the polypyrrole (PPy) decorated multi-walled carbon nanotubes (WMCNTs), was decreased to 109 Ω even the mass ratio was only 1%wt, which could be used a promising candidate as self-repairing materials in the field of antistatic.
The unavailability of clean drinking water is one of the significant health issues in modern times. Industrial dyes are one of the dominant chemicals that make water unfit for drinking. Among these ...dyes, methylene blue (MB) is toxic, carcinogenic, and non-biodegradable and can cause a severe threat to human health and environmental safety. It is usually released in natural water sources, which becomes a health threat to human beings and living organisms. Hence, there is a need to develop an environmentally friendly, efficient technology for removing MB from wastewater. Photodegradation is an advanced oxidation process widely used for MB removal. It has the advantages of complete mineralization of dye into simple and nontoxic species with the potential to decrease the processing cost. This review provides a tutorial basis for the readers working in the dye degradation research area. We not only covered the basic principles of the process but also provided a wide range of previously published work on advanced photocatalytic systems (single-component and multi-component photocatalysts). Our study has focused on critical parameters that can affect the photodegradation rate of MB, such as photocatalyst type and loading, irradiation reaction time, pH of reaction media, initial concentration of dye, radical scavengers and oxidising agents. The photodegradation mechanism, reaction pathways, intermediate products, and final products of MB are also summarized. An overview of the future perspectives to utilize MB at an industrial scale is also provided. This paper identifies strategies for the development of effective MB photodegradation systems.
•Lipase/Zn3(PO4)2 hybrid nanoflower is prepared by a facile and rapid method.•Formation mechanism of the novel hybrid materials is illustrated in detail.•Compared with free lipase, enzymatic activity ...increment of lipase/Zn3(PO4)2 is 147%.•The as-prepared immobilized lipase shows excellent operational stability.•Lipase/Zn3(PO4)2 shows potential application in industrial enzyme catalysis.
A facile and rapid method is reported in this paper to prepare a novel immobilized enzyme named lipase/Zn3(PO4)2 hybrid nanoflower. The growth mechanism of the nanoflower has been studied in detail and can be described as the following four steps: crystallization and coordination, in-situ precipitation, self-assembly, size growth. Addition amount of lipase, reaction temperature and stirring form affect the morphology and lipase content of the hybrid nanoflower. Besides, the catalytic performance of lipase/Zn3(PO4)2 hybrid nanoflower was investigated and the optimal catalytic conditions have been found. The maximum enzyme activity was 855±13U/g. In comparison with the free lipase, the enzyme activity increment of hybrid nanoflower is 147%. Meanwhile, the unique nanostructure makes lipase/Zn3(PO4)2 hybrid nanoflower an excellent operational stabilizer. The results indicate that the well-designed materials should be useful in industrial enzyme catalysis.
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•P(MMA-AA-DVB)/Fe3O4 Janus particles in micro scale were prepared by solvothermal process.•P(MMA-AA-DVB)/Fe3O4 effectively attached to the stable emulsified water droplets in ...emulsion.•The obtained Janus particles expressed excellent recycling property for separation of water in crude oil emulsion.•The recycled P(MMA-AA-DVB)/Fe3O4 retained its interfacial activity, surface morphology after demulsification.
This paper focuses on the synthesis of micro scale Poly(methylmethacrylate-acrylic acid-divinylbenzene) iron oxide Janus magnetic submicronic particles and the investigation of their interfacial properties and demulsifying capacity. The surface morphology, polymerization process and magnetic properties of the magnetic Janus submicronic particles were characterized by laser particle size analyzer, transmission electron microscopy, vibrating sample magnetometer. The interfacial activity and high hydrophilic nature of P(MMA-AA-DVB)/Fe3O4 Janus magnetic submicronic particles allowed them to be effectively attached to stable emulsified water droplets in heavy crude oil water emulsion. Janus magnetic submicronic particles tagged water droplets were readily removed by an external magnetic field. Our experimental results showed efficient removal of the water from the heavy crude oil emulsion. It was found that external magnetic field enhances the coalescence of magnetically tagged water droplets in an emulsion. The magnetic property of P(MMA-AA-DVB)/Fe3O4 allowed the used Janus magnetic submicronic particles to be readily recycled by magnetic separation and solvent washing. The recycled P(MMA-AA-DVB)/Fe3O4 was found to retain its interfacial activity and was effective in breaking the heavy crude oil water emulsion. This study demonstrated that Janus magnetic submicronic particles demulsification represented a new route of removing emulsified water from crude oil and water emulsions.
A novel bovine serum albumin surface-imprinted thermosensitive magnetic composite microsphere was successfully prepared by the surface grafting copolymerization method in the presence of ...temperature-sensitive monomer N-isopropylacrylamide (NIPAM), functional monomer methacrylic acid (MAA) and cross-linking agent N,N′-methylenebisacrylamide (MBA). The structure and component of the thermosensitive magnetic molecularly imprinted microsphere were investigated by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). The results of thermosensitivity, adsorption capacity, selectivity and reusability showed the formation of a thermosensitivity grafting polymer layer P(NIPAM–MAA–MBA) on the surface of Fe3O4@SiO2 and the good adsorption capacity and specific recognition for template protein. When the adsorption temperature was higher than the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAM), shape memory effect of imprinted cavities would be more effective. In other words, it was more conducive to capture template molecules under this condition and the imprinting factor would be higher. On the other hand, when the desorption temperature was lower than LCST of PNIPAM, the decrease of shape memory effect between imprinted cavities and template molecules would facilitate the release of template molecules from the imprinted cavities. Based on this property, the adsorption and desorption of template molecules could be regulated by system temperature indirectly which benefited from the existence of thermosensitivity imprinting layer.
•Bovine serum albumin surface-imprinted thermosensitive magnetic polymer microspheres Fe3O4@SiO2@BSA-MIP(NIP) were prepared.•The adsorption of template molecule could be regulated by system temperature.•The adsorption capacity, imprinting factor and reusability of Fe3O4@SiO2@BSA-MIP were satisfactory.
The real-world graphs are full of noises and perturbation. However, recent studies show that the existing graph neural networks (GNNs) are usually sensitive to the quality of the input graph. In this ...work, we propose a graph alternate learning (GAL) framework to alternately train dual models, i.e., prediction network to learn the graph structure for node classification tasks and graph regularization network to enhance the robustness of GNNs. The adoption of dual models, which learn and teach each other collaboratively at the entire training process, drives the formation of a better graph structure. Furthermore, a node feature selection method is integrated into the GAL network to reduce the influence of node attack. Lastly, in order to evaluate the anti-attack ability of GAL, we devise a smooth input graph adversarial attack, called
Smooth-Attack
, which can degrade the node classification performance of graph convolutional networks (GCN) and is considered to be a form of over-smoothing. Experiments show that our proposed GAL model can keep superiority on benchmark datasets under edge and node perturbation, and GAL is highly robust against
Smooth-Attack
.
Abstract Our recent studies have identified increased expression of miR-21 in brain following traumatic brain injury (TBI), which alleviated brain edema that related to the blood–brain barrier (BBB) ...leakage. To analyze the potential effect of miR-21 on secondary BBB damage after TBI, we employed the fluid percussion injury rat model and manipulated the expression level of miR-21 in brain. We found that miR-21 level in brain microvascular endothelial cells (BMVECs) in lesioned cerebral cortex can be upregulated or downregulated by intracerebroventricular infusion of miR-21 agomir or antagomir. Upregulated miR-21 level conferred a better neurological outcome of TBI, and alleviated TBI-induced secondary BBB damage and loss of tight junction proteins. To explore the molecular mechanism underlying this protective effect, we detected the impact of miR-21 on the expression of Angiopoietin-1(Ang-1) and Tie-2, which can promote the expression of tight junction proteins and amplify BBB stabilization. We found that miR-21 exerts the protective effect on BBB by activating the Ang-1/Tie-2 axis in BMVECs. Thus, miR-21 could be a potential therapeutic target for interventions of secondary BBB damage after TBI.
Traumatic brain injury (TBI) tends to cause disruption of the blood-brain barrier (BBB). Previous studies have shown that intravenously or intracerebroventricularly infused human umbilical cord ...blood-derived endothelial colony-forming cells (ECFCs) can home to injury sites and improve outcomes in mice subjected to experimental TBI. Several reports have demonstrated that these cells did not incorporate directly into newly formed vasculature but instead stimulated the proliferation and migration of tissue-resident endothelial cells (ECs) via paracrine mechanisms. In the present study, exosomes, which range from 30 to 150 nm in diameter, were isolated from ECFC-conditioned medium. The exosomes were labeled with PKH67 ex vivo, and we observed that they were taken up by ECs with high efficiency after 12 h of incubation. Pretreatment with ECFC-derived exosomes promoted the migration of ECs subjected to scratch injury, and incubating ECs exposed to hypoxia with ECFC-derived exosomes decreased PTEN expression, stimulated AKT phosphorylation and increased tight junction (TJ) protein expression in the cells. Furthermore, in vivo delivery of ECFC-derived exosomes into TBI mice also inhibited PTEN expression and increased AKT expression, changes accompanied by reductions in Evans blue (EB) dye extravasation, brain edema and TJ degradation. These data demonstrated that ECFC-derived exosomes have beneficial effects on BBB integrity in mice with TBI.
•ECFC-exosomes labeled with PKH67 could be internalized by endothelial cells with high efficiency after 12 h of incubation.•Pretreatment with ECFC-derived exosomes attenuated the degradation of the tight junction proteins of endothelial cells.•Transfer of exosomes into TBI mice alleviated the disruption of blood-brain barriers, EB extravasation and brain edema.
A novel bovine serum albumin (BSA) surface-imprinted magnetic microsphere was fabricated by copolymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC), functional monomer acrylamide and ...cross-linking agent N,N′-methylenebisacrylamide on the surface of Fe3O4@SiO2 microsphere. Here, MPC was creatively and strategically introduced to the protein-imprinted polymer as an assistant monomer to reduce nonspecific adsorption of competitive protein. 10mol% of MPC was determined as the optimal content according to the imprinting factor. The structure and component of the obtained imprinted microsphere were studied by different characterization methods. The rebinding specificity experiments showed that the recognition specificity of the BSA-imprinted microsphere was greatly improved by introducing MPC. The corresponding adsorption capacity and imprinting factor were 21.79mg/g and 8.32, respectively. More significantly, the selectivity coefficients of BSA to human serum albumin, ovalbumin, lysozyme, Cytochrome C and Ribonuclease A could reach up to 1.63, 5.23, 9.14, 7.43 and 7.23, respectively, benefited by the protein restricted access function of MPC polymer. Furthermore, this strategy had an excellent versatility and was also suitable for another template, lysozyme. The proposed strategy herein provided an effective means for improving recognition specificity of molecularly imprinted polymers and was expected to use in the improvement of detection sensitivity of molecularly imprinted biosensors.
The “glue+particles” approach has presented an excellent idea for promoting the practicability of superamiphiphobic surfaces. However, strong polar materials, such as epoxy and polyurethane, are ...usually employed as adhesives. The superamphiphobic behavior will be immediately lost when parts of superhydrophobic particles are removed. Thus, a glue with robust self-healing liquid-repellence is desirable, but remains challenging to realize. Herein, a robust, self-healable, superamphiphobic film was fabricated by a liquid-repellent “glue+particles” approach. The coating based on a sol-gel network showed exceptional liquid-repellency to low surface tension liquids including ethanol. The designed coating is based on robust sol-gel network dangling fluoroalkyl chains which integrates the bonding and self-healing mechanisms for providing a longer usage life. It could withstand at least 400cycles of abrasion under severe stress (45kPa), strong acid/base solution, hot-liquids and smudge treatment without apparently changing the superamphiphobicity. This novel and effective coating system may be useful for the development of robust protective clothing for various applications.
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•An intriguing liquid-repellent “glue+particles” approach has been presented.•The coating based on a sol-gel silica network shows exceptional liquid-repellency.•The coating can restore the super liquid-repellent properties to multi-damages.•The sol-gel network integrates two mechanisms for a long-lived superamphiphobic coating.
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