Polypropylene (PP), as a general thermoplastic polymer, is broadly used in different fields. However, the high flammability, melt dripping and poor mechanical properties of PP are a constraint to the expansion of its applications. In this paper, PP composites containing a combination of a phenethyl-bridged DOPO derivative (PN-DOPO) and organic montmorillonite (OMMT) were prepared via melt blending. The synergistic effects of PN-DOPO and OMMT on the flame retardancy, thermal stability and mechanical properties of PP composites were investigated systematically. The results showed that 20 wt% addition of PN-DOPO with OMMT improved the flame retardancy of PP composites. In particular, the introduction of 17 wt% PN-DOPO and 3 wt% OMMT increased the LOI values of the PP matrix from 17.2% to 23.6%, and the sample reached the V-0 level and reduced the heat release rate and total heat release. TGA indicated that OMMT could improve the thermal stability of the PP/PN-DOPO blends and promote the char residues of PP systems. Rheological behaviour showed a higher storage modulus, loss modulus and complex viscosity of PP/PN-DOPO/OMMT composites, suggesting a more effective network structure. In addition, the tensile strength, flexural properties and impact strength of the PP/PN-DOPO/OMMT composites actually increased for a good dispersion effect. Combined with the char layer analysis, the introduction of OMMT promoted more continuous and compact structural layers containing an aluminium–silicon barrier and phosphorus-containing carbonaceous char in the condensed phase. OMMT can improve the flame retardancy, thermal stability and mechanical properties of PP, and, thus, PN-DOPO/OMMT blends can serve as an efficient synergistic system for flame-retarded PP composites.
The graphene nanosheets (GNS)/polydimethylsiloxane (PDMS) composite films with out-of-plane dielectric actuation behavior were prepared through a layer-by-layer spin coating process. The GNS-PDMS/PDMS composite films with 1~3 layers of GNS-PDMS films were spin coated on top of the PDMS film. The dielectric, mechanical, and electromechanical actuation properties of the composite films were investigated. The dielectric constant of the GNS-PDMS3/PDMS composite film at 1 kHz is 5.52, which is 1.7 times that of the GNS-PDMS1/PDMS composite film. The actuated displacement of the GNS-PDMS/PDMS composite films is greatly enhanced by increasing the number of GNS-PDMS layers. This study provides a novel alternative approach for fabricating high-performance actuators with out-of-plane actuation behavior.
Background: Blueberry anthocyanin such as Cyanidin-3-O-glucoside may help prevent Alzheimer’s disease. We aimed to investigate the preventive and therapeutic effects of Cyanidin-3-O-glucoside against Aβ1–42-induced apoptosis of SH-SY5Y cells as well as the underlying mechanisms. Methods: Cell viability and intracellular and mitochondrial reactive oxygen species were detected by MTT, a reactive oxygen species detection kit, and a MitoSOX red mitochondrial superoxide indicator. The mitochondrial membrane potential, intracellular calcium ion content, and adenotriphophate (ATP) were identified via a mitochondrial membrane potential detection kit, calcium ion detection kit, and ATP detection kit, and apoptosis was detected via flow cytometry. Transcription of apoptosis-related genes was detected using real-time fluorescence quantitative polymerase chain reaction, and expression of apoptosis-related proteins was identified using Western blot. Results: We found that Cyanidin-3-O-glucoside could downregulate the expression of cytochrome c, caspase 9, caspase 3, and other genes and proteins, which consequently reduced the rate of apoptosis. Additionally, it could upregulate Bcl-2 gene and protein expression, downregulate Bax gene and protein expression, regulate mitochondrial membrane permeability and calcium-release channels, reduce calcium influx into mitochondria, maintain intracellular calcium ion levels, reduce intracellular levels of reactive oxygen species and increase ATP levels, maintain the mitochondrial membrane potential at a normal level, maintain normal mitochondrial functioning, and prevent apoptosis. Discussion: Taken together, Cyanidin-3-O-glucoside showed dose-dependent preventive and therapeutic effects against Aβ1–42-induced apoptosis of SH-SY5Y cells. Conclusions: Cyanidin 3-O-glucoside showed a better preventive effect than therapeutic effect against Aβ1–42-induced apoptosis in SH-SY5Y cells.
A 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based derivative (PN-DOPO) combined with aluminium phosphates-coated sepiolite (Sep@AlPO4) was used to improve the flame retardance, thermal stability and mechanical performances of poly (ethylene oxide) (PEO)/poly (butylene adipate-co-terephthalate) (PBAT) blends. The synergistic effects of PN-DOPO and Sep@AlPO4 on flame-retarded PEO/PBAT composites were systematically discussed. Results indicated that introducing 5 wt% Sep@AlPO4 with 10 wt% PN-DOPO into PEO/PBAT achieved a V-1 rating for the UL-94 test and increased the limiting oxygen index value to 23.7%. Moreover, the peak heat release rate (p-HRR), average HRR and total heat release values of PEO/PBAT/PN10%/Sep5% composites decreased by 35.6%, 11.0% and 23.0% compared with those of PEO/PBAT, respectively. Thermogravimetric analysis (TGA) results confirmed that PN-DOPO/Sep@AlPO4 enhanced the initial thermal stability and char yield of PEO/PBAT matrix, and TGA/Fourier transform infrared spectrometry results revealed that the composites exhibited the characteristic absorption peaks of phosphorous-containing groups and an increase in gas-phase volatiles during thermal degradation. The morphological structures of the residues indicated that PN-DOPO and Sep@AlPO4 mixtures produced a more dense and continuous char layer on the composite surface during burning. Rheological behaviour revealed that higher complex viscosity and modulus values of PEO/PBAT/PN-DOPO/Sep@AlPO4 sample could also promote the crosslinking network structure of condensed phases during combustion. Furthermore, the PEO/PBAT/PN-DOPO/Sep@AlPO4 composites exhibited superior elongation at break and flexural performance than the PEO/PBAT system. All results demonstrated that the PEO/PBAT system modified with PN-DOPO/Sep@AlPO4 showed remarkable flame retardance, and improved thermal stability and mechanical properties, indicating its potential application in areas requiring fire safety.
Postharvest autolysis severely compromises the commercial value of fresh Dictyophora rubrovolvata. This study integrated physiological, ultrastructural, and metabolomic analyses to elucidate the underlying mechanism. Results indicated a continuous decline in cellular adenosine triphosphate levels during storage, leading to an energy crisis and triggering cellular stress responses. Metabolomic analysis revealed that the fruiting bodies activate pathways such as glycolysis and the pentose phosphate pathway through metabolic reprogramming to maintain homeostasis. However, the intensifying energy crisis inhibited Calcium ion ATPase activity, disrupting ion homeostasis and leading to Ca2+ influx. This activated phospholipases and initiated membrane lipid degradation, accompanied by a burst of reactive oxygen species and elevated levels of H2O2 and malondialdehyde, creating a vicious cycle of oxidative stress. Concurrently, cell wall components (chitin, β-1,3-glucan, cellulose) are accelerated in degradation due to the upregulation of corresponding hydrolases. Transmission electron microscopy confirmed progressive disintegration of cellular structures, including mitochondria, the plasma membrane, and the cell wall. These findings establish an “energy-membrane lipid-cell wall” cascade framework, revealing that D. rubrovolvata autolysis is an active, orderly form of programmed cell death under energy stress. This study provides new insights into the physiological mechanisms of postharvest quality deterioration in edible fungi.
A bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (PN-DOPO) in combination with aluminum phosphates coated sepiolite (Sep@AlPO4) was used to improve the flame retardancy, thermal stability and mechanical properties of poly (ethylene oxide) (PEO)/poly (butylene adipate-co-terephthalate) (PBAT) blends. The synergistic effects of PN-DOPO and Sep@AlPO4 on the fire resistance, thermal decomposition behavior and mechanical properties of PEO/PBAT composites were investigated systematically. The results indicated that 5 wt % Sep@AlPO4 combined with 10 wt% PN-DOPO into PEO/PBAT achieved a V-1 rating in UL-94 test and the LOI value increased to 23.7%, meanwhile, the peak-heat release rate (p-HRR), av-HRR and total heat release (THR) values of PEO/PBAT/PN10%/Sep5% composites decreased by 35.6%, 11.0% and 23.0% compared with those of PEO/PBAT, respectively. The thermogravimetric analysis (TGA) results confirmed that PN-DOPO/Sep@AlPO4 could enhance the initial thermal stability and char yield of PEO/PBAT matrix, and TGA/Fourier transform infrared spectrometry (TGA-FTIR) results revealed that the composites exhibited the absorption peaks of phosphorous-containing groups and an increase in gas-phase volatiles during the thermal decomposition process. The digital photographs and morphological structures of char residues demonstrated that PN-DOPO and Sep@AlPO4 mixtures benefited to the formation of a more continuous and dense carbon layer on the composites surface during combustion. Rheological behavior revealed that a higher storage modulus, loss modulus and complex viscosity of PEO/PBAT/PN-DOPO/Sep@AlPO4 composites could also promote the cross-linking structure during burning. Furthermore, the PEO/PBAT/PN-DOPO/Sep@AlPO4 composites exhibited excellent mechanical properties in terms of elongation at break and flexural performance than the PEO/PBAT system. All the results demonstrated that PEO/PBAT system modified by the combination of PN-DOPO and Sep@AlPO4 not only exhibited excellent synergistic effect on the flame retardance, but also had good improvement on thermal stability and mechanical properties, indicating the potential application in areas requiring fire safety.