Hydrogen peroxide (HO) acts as a signaling molecule in response to cold stress. Mitogen-activated protein kinases (MAPKs) and C-repeat/dehydration-responsive factor (CBF) play important roles in cold response regulation. To investigate the roles of MAPKs and CBF in HO-induced chilling tolerance, tomato (Solanum lycopersicum cv. Ailsa Craig) plants were treated with 1 mM HO before chilling treatment. The results showed that HO treatment protected subcellular structure, increased concentrations of abscisic acid (ABA), zeatin riboside (ZR), and methyl jasmonate (MeJA), but decreased the concentration of gibberellic acid (GA). Furthermore, 1 mM HO treatment enhanced the activities of antioxidant enzymes. Meanwhile, relative expressions of SlMAPK1/2/3 and SlCBF1 in HO-treated plants were higher than those in the control. Our findings suggest that HO treatment might enhance the chilling tolerance of tomato plants by activating SlMAPK1/2/3 and SlCBF1 gene expression and by regulating phytohormone concentrations and antioxidant enzyme activities.
Curcumin, a natural polyphenolic compound, offers a wide range of pharmacological benefits such as antioxidant, anti-inflammatory and anti-cancer. The oil-in-water nanoemulsions containing curcumin were obtained by high pressure homogenization and effects of various emulsifiers (Tween-80, lecithin, whey protein isolate and acacia) and different surfactant-to-oil ratios (SOR) on physicochemical characteristics, physical stability and storage stability of curcumin loaded nanoemulsions were evaluated in this study. The result showed that smaller particle size, better physical and storage stabilities and higher curcumin content were found in curcumin loaded nanoemulsions stabilized with Tween-80 and lecithin. Compared with nanoemulsions prepared with lecithin, nanoemulsions fabricated with Tween-80 exhibited better uniformity and distribution as demonstrated by microscopic observations. It was found that SOR was positively correlated with particle size but negatively correlated with curcumin content in the emulsion droplets. Neither the emulsifier nor SOR values were found to have significant effects on zeta-potentials of the droplets. This result implied that curcumin loaded nanoemulsions prepared with Tween-80 and higher SOR values helped curcumin to achieve better physical stability and storage stability.
In the present study, different ratios of layered double hydroxides (LDHs) were synthesized via co-precipitation method. The synthesized LDHs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nitrogen adsorption-desorption analysis, point of zero charges (pHpzc), scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM). Phosphate adsorption performances were estimated by batch adsorption experiments, desorption hysteresis and adsorption mechanism were also investigated. The XRD, SEM and TEM results confirmed the multilayer structure of the synthesized LDHs. The pseudo-second-order kinetic model and the Freundlich model describes the adsorption behavior of LDHs best. The maximum adsorption capacity is 185.86 mg-KH2PO4/g for Mg2Al-NO3 LDH. When the dosage of LDHs is greater than 2 g/L, the phosphorus content in the solution decreased from 30 mg-P/L to 0.077 mg-P/L after adsorption by Mg2Al-NO3 LDH. All the results reveal that Mg2Al-NO3 LDH is a potential adsorbent for removing phosphate from aqueous solution.
In this study, a new type of ammonium polyphosphateintercalated organic montmorillonite (APP/OMt) was synthesized using in-situ polymerization, and the chemical structure and surface morphology of APP/OMt was confirmed by FT-IR, XRD, EDS and SEM. Moreover, the intumescent flame retardant (IFR) composed of APP/OMt, pentaerythritol (PER) and melamine (MA) was added into polypropylene (PP) to fabricate the PP/IFR APP/OMt composites, and their flame-retardant and mechanical properties were characterized systematically. When the additive mass of the flame retardants was 30 %, the limiting oxygen index (LOI) value reached 33.3 %, and the UL-94 test passed the V-0 level when the added amount was only 20 %. Especially, compared to the counterpart of IFR APP , the addition of IFR APP/OMt dramatically decreased the released smoke of PP during combustion, and the quality of carbon layer after combustion was obviously improved. The flame-retardant mechanism of IFR APP/OMt was deeply explored. In addition, the mechanical properties of PP composites with IFR APP/OMt were significantly improved compared with IFR APP . The enhanced flame retardancy and mechanical strength were attributed to the synergistic effect between OMt and IFR particles along with improved the dispersion of IFR APP/OMt within the PP matrix.
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