The fabrication of SBS-g-COOH/ZnO composites cross-linked by Zn2+ salt-bondings was reported. First, SBS-g-COOH with different grafting ratio was synthesized through the thermally induced thiol–ene ...click reaction, which was corroborated by FT-IR and 1H NMR. Next, zinc oxide (ZnO) was added to coordinate with the carboxyl groups of SBS-g-COOH to obtain the Zn2+ salt-bondings. TEM images, demonstrating the ion-rich domains with size of 30–50 nm, substantiated the formation of Zn2+ salt-bondings and also exhibited that the size and density of ion domains increased with the increasing content of ZnO. The salt-bondings effectively enhanced the mechanical properties of SBS-g-COOH/ZnO composites, achieving a maximum tensile stress of 14.24 MPa at 100% strain and a Young’s modulus of 14.19 MPa, which were almost 4.49 times and 4.35 times larger than that without ZnO, respectively. Simultaneously, the ionic networks cross-linked by salt-bondings endowed the composites with feasible shape memory behaviors that the best shape recovery ratio could be up to 97%.
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•A novel method was proposed to prepare thermoplastic vulcanizates.•The micron-sized CuSO4 particles were converted into nanoparticles by this strategy.•The CuSO4 nanoparticles were ...used as both reinforcement and cross-linkers for NBR.•The incorporation of CuSO4 realized the balanced stiffness-toughness of the TPVs.•The TPVs showed co-continuous structure, achieving excellent shape memory property.
In the field of dynamic vulcanization, irreversible covalent bonds are utilized to fabricate thermoplastic vulcanizates (TPVs) generally. In this work, a new strategy, metal-ligand coordination-induced dynamic vulcanization, is presented to design polylactide (PLA)/butadiene acrylonitrile rubber (NBR)/cupric sulfate (CuSO4) TPVs with balanced stiffness-toughness and shape memory property. During dynamic vulcanization, the micron-sized CuSO4 particles have been transformed into nanoparticles by the process of “dissolution-reaction-redissolution-reaction” and then distributed in the continuous NBR phase. CuSO4 nanoparticles cross-link NBR through the coordination interaction between nitrile groups and copper ions, and simultaneously reinforce the NBR phase. This endows the TPVs with balanced stiffness-toughness properties: notched Izod impact strength of 152.88 kJ/m2 and tensile strength of 22.30 MPa. Furthermore, the fabricated TPVs exhibit co-continuous morphology which resulted in excellent shape memory effect of obtaining shape recovery ratio of 92.30%. We present a novel approach to toughen and enhance PLA-based shape memory materials simultaneously, and it may expand the research scope of dynamic vulcanization.
The application of bio-based materials such as biodegradable films for food packaging to reduce the use of non-biodegradable petroleum-based food packaging materials is of great significance to ...alleviate environmental pollution. Here, we use a simple and efficient method to design a multifunctional food packaging film with biodegradability, antifogging and antibacterial properties based on carboxymethyl chitosan/polyvinyl alcohol crosslinked network by using citric acid as crosslinker. The resultant films exhibited many desirable and impressive features, such as good mechanical properties, antifogging, antibacterial and biodegradable. The citric acid (CA) was used not only as multifunctional cross-linkers via hydrogen bonding with polyvinyl alcohol (PVA) and carboxymethyl chitosan (CMCS) but also as effective reinforcers to improve mechanical and antibacterial properties of the composite films. As CA contents achieved 5 wt%, the tensile strength of films increased from 21.03 MPa to 29.65 MPa, and the Young's modulus increased from 3.71 MPa to 10.87 MPa. It was found that CMCS and CA affected the crystallization situation of PVA composite films and helped to promote the soil microbial degradation of films. CA enhanced the crosslinking between PVA and CMCS, forming a crosslinked network, improving the thermal stability of the composite films and decreasing its water vapor permeability and swelling properties. More importantly, the prepared antifogging film can not only relatively delay the water loss of strawberries and cherry tomatoes, but also significantly reduce the growth of bacteria, and thus extending the shelf life. Therefore, this report provided a new solution to alleviate non-degradable plastic problem which illustrates its potential for food preservation and packaging applications.
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•A multifunctional film based on a crosslinked network was designed and constructed.•CA enhanced the mechanical property and made PVA/CMCS films antibacterial.•CMCS and CA helped to promote the soil microbial degradation of PVA composite films.•The PVA/CMCS/CA films were antifogging, antibacterial and biodegradable.
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•High efficiency biochar adsorbent was prepared from crab shell waste.•The biochar adsorbent had high adsorption capacity of 28140.5 mg·g−1 for MG.•The adsorption capacity could reach ...6142.5 mg·g−1 within 3 minutes.•Adsorption mechanisms were alkaine fading, H-bonds and π-π interaction.
In this study, waste crab shell was hydrothermally carbonized and then activated to prepare an effective and recyclable adsorbent. The adsorption performance of the adsorbent for different dyes was investigated through adsorption experiments, and the results showed that it had the largest adsorption performance for malachite green. Furthermore, the adsorption performance and mechanism of malachite green were investigated by static and dynamic adsorption method. The crab shell biochar could remove 6142.5 mg g−1 of malachite green within 3 minutes, indicating that the crab shell biochar could ultra-rapid and highly efficient adsorb malachite green. In addition, the malachite green adsorbed on the crab shell biochar could be removed by calcination, which achieved the entire regeneration of the crab shell biochar. The adsorption of malachite green by crab shell biochar adsorbent conformed to the pseudo-second-order kinetic model, the Dubinin-Radushkevich and Langmuir isotherm adsorption model. Physical and chemical characterization indicated that the adsorption mechanism of malachite green included alkaline fading effect, hydrogen bonding and π-π interaction.
The transition from pregnancy to lactation is characterized by a progressive decrease in insulin sensitivity. Propionate increases with dietary fiber consumption and has been shown to improve insulin ...sensitivity. Recent studies suggest that plasma odd-chain fatty acids OCFAs; pentadecanoic acid (C15:0) and heptadecanoic acid (C17:0) that inversely correlated with insulin resistance are synthesized endogenously from gut-derived propionate. The present study investigated the effects of soluble fiber during gestation on gut microbiota, plasma non-esterified fatty acids and insulin sensitivity in sows. Sows were allocated to either control or 2.0% guar gum plus pregelatinized waxy maize starch (SF) dietary treatment during gestation. The SF addition changes the structure and composition of gut microbiota in sows. Genus
increased by SF addition may promote intestinal propionate production. Moreover, the dietary SF increased circulating levels of plasma OCFAs, especially C17:0. The SF-fed sows had a higher insulin sensitivity and a lower systemic inflammation level during perinatal period. Furthermore, the plasma C15:0 and C17:0 was negatively correlated with the area under curve of plasma glucose after meal and plasma interleukin-6. In conclusion, dietary SF improves insulin sensitivity and alleviates systemic inflammation in perinatal sows, potentially related to its stimulating effect on propionate and OCFAs production.
Abstract Epithelial-to-mesenchymal transition (EMT) is considered to play an essential role in progression and metastasis. This study aims to investigate the expression and underlying molecular ...targets of high-mobility group AT-hook 2 (HMGA2) in the progression of colon cancer. The expression of HMGA2 is upregulated by both active extracellular signal-regulated kinase (ERK)1/2 and TGF-β signaling in colon cancer cells through a series of lentiviral infection and pharmacological assays. HMGA2 knockdown by specific shRNAs attenuates proliferation, motility and invasion of colon cancer cells in vitro and in vivo . Besides, exogenous HMGA2 expression caused EMT in colon cancer cells, which was confirmed by the downregulation of the epithelial markers and the upregulation of the mesenchymal markers. Moreover, HMGA2 positively regulates the Slug expression by directly binding to the regulatory region in Slug promoter. Importantly, the knockdown of Slug could reverse the HMGA2-induced EMT and decrease the migration and invasion ability of colon cancer cells. Taken together, our results reveal a critical role for HMGA2 in promoting EMT, migration, invasion, and proliferation of colon cancer cells, suggesting HMGA2 as a potential molecular target to prevent colon cancer progression.
Shape memory polymers (SMPs) based on fully biobased poly(lactide) (PLA)/natural rubber (NR) thermoplastic vulcanizates (TPVs) were fabricated via peroxide-induced dynamic vulcanization. ...Simultaneously, in situ reactive compatibilization was achieved by PLA molecule grafting onto NR chains. Differing from the general concept of spherical rubber particles being formed after dynamic vulcanization, the cross-linked NR was found to be a “netlike” continuous phase in the PLA matrix. This novel structure explained the surprising shape memory property of PLA/NR TPVs well (shape fixities ∼ 100%, shape recoveries > 95%, and fast recovery speed < 15 s at the switching temperature, ∼60 °C): the cross-linked NR continuous phase offers strong resilience and the PLA phase serves as the heat-control switch. We envision that the “green” raw materials and excellent shape memory properties of the dynamically vulcanized PLA/NR SMPs will open up a wide range of potential applications in intelligent medical devices.
► We explore using CNs to reinforce XSBR matrix for preparation of a nanocomposite. ► CNs could form a strong filler network in the XSBR matrix. ► Good compatibility and interfacial adhesion between ...XSBR and CNs. ► Significant increase in tensile strength and tear strength with increasing CNs.
A series of carboxylated styrene-butadiene rubber (XSBR)/cellulose nanocrystals (CNs) latex composites were successfully prepared. The vulcanization process, morphology, dynamic viscoelastic behavior, dynamic mechanical property, thermal and mechanical performance of the XSBR/CNs composites were investigated in detail. The results revealed that CNs were dispersed uniformly in the XSBR matrix and formed a strong filler–filler network. The dynamic mechanical analysis (DMA) showed that the glass transition temperature (Tg) of XSBR matrix was shifted from 48.45 to 50.64°C with 3phr CNs, but decreased from 50.64 to 46.28°C when further increasing CNs content up to 15phr. The composites exhibited a significant enhancement in tensile strength (from 16.9 to 24.1MPa) and tear strength (from 43.5 to 65.2MPa) with loading CNs from 0 to 15phr. In addition, the thermo-gravimetric analysis (TGA) showed that the temperature at 5% weight loss of the XSBR/CNs composites decreased slightly with an increase of the CNs content.
In humans, the metabolic and immune changes occurring during perinatal period also describe metabolic syndrome. Gut microbiota can cause symptoms of metabolic syndrome in pregnant women. Increased ...gut permeability is also involved in metabolic disorders in non-pregnant hosts. However, longitudinal studies investigating the changes in metabolic characteristics, gut microbiota, and gut permeability of sows throughout pregnancy and lactation are lacking. The correlation between gut microbiota and metabolic status of sows is also poorly known. The present study was conducted to investigate the temporal variations in sow metabolic characteristics, gut microbiota, gut permeability, and gut inflammation at days 30 (G30) and 109 (G109) of gestation and days 3 (L3) and 14 (L14) of lactation. Results showed that insulin sensitivity was decreased in L3. Circulating concentrations of pro-inflammatory cytokine IL-6 increased in G109 and L3. 16S rRNA gene sequencing of the V3-V4 region showed that gut microbiota changed dramatically across different reproductive stages. The bacterial abundance and alpha diversity in L3 were the lowest. The phyla
and
exhibited the highest relative abundance in L3. Among the genera,
,
, and
were highest, but
the lowest, in relative abundance in L3. The fecal levels of acetate and total short-chain fatty acids were increased in G109, but fecal butyrate concentrations were markedly decreased in L3. The plasma zonulin concentrations, a biomarker for gut permeability, were increased in G109 and L3. The plasma endotoxin concentrations were increased in L3. Furthermore, levels of fecal lipocalin-2 and pro-inflammatory cytokines IL-6 and TNF-α were increased in G109 and L3. In contrast, fecal levels of anti-inflammatory cytokine IL-10 were significantly decreased in G109 and L3. Additionally, the increased relative abundances of
in L3 were positively correlated with plasma zonulin and fecal endotoxin but negatively correlated with fecal IL-10. These findings indicate that the mother sow exhibits a metabolic syndrome and dramatical changes in gut microbiota during perinatal period, especially in early lactation. Besides, increased gut permeability and plasma endotoxin concentrations caused by negative microbial changes would possibly be the potential mechanisms under which sow's metabolic disorders and inflammatory status were exacerbated during early lactation.
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•CMCS assisted to the dispersion of Fe3O4 and reduced the agglomeration of Fe3O4.•The interfacial compatibility between Fe3O4 and XSBR matrix had improved.•Hybrid filler-network of ...regenerated CMCS-Fe3O4 improve mechanical properties.•Tensile strength 12.66 MPa, Tg 4.22 °C, saturation magnetization 11.27 emu/g.
Achieving fillers well-distributed in the polymeric matrix via a green and eco-friendly method is critical for composites preparation to gain considerable comprehensive properties. In this work, we describe Fe3O4-based magnetic elastomer composites with superior mechanical, thermal and magnetic properties via a latex film-forming approach by using carboxylic styrene butadiene rubber (XSBR) as rubber matrix and carboxymethyl chitosan (CMCS) as a dispersant for Fe3O4. It was found that CMCS promoted the dispersion of Fe3O4 remarkably and improved the interfacial compatibility between Fe3O4 and XSBR matrix. Simultaneously, the XSBR/CMCS/Fe3O4 composite with 25 wt% Fe3O4 displayed a higher tensile strength was about 2.5 times of the neat XSBR. And the saturation magnetization of the XSBR/CMCS/Fe3O4 composite was about 1.2 times that of XSBR/Fe3O4 at the same filler content. Therefore, this report provided a new solution to uniformly disperse Fe3O4 in rubber composites by latex film-forming method without any dispersion guarantee measures.
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