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In order to prolong the storage period of ‘Huangguan’ pear and reduce the deterioration of fruit quality during long-term storage and subsequent shelf life, this study conducted preharvest treatment with different concentrations of aminoethoxyvinylglycine (AVG) to ‘Huangguan’ pear. Before and after refrigeration for 180 days and after subsequent shelf life for 7 days, quality indicators were tested. The results showed that compared with the control group, preharvest AVG treatment delayed the decline of fruit firmness, maintained higher contents of soluble solids and titratable acids, and effectively inhibited fruit surface browning and core browning, the most pronounced effect being observed at 200 mg/L AVG. During long-term cold storage, the contents of arbutin, chlorogenic acid and total phenols increased with the occurrence of core browning, and the activity of polyphenol oxidase (PPO) increased. The expression levels of PbPAL1, PbPAL2, PbPPO1, PbPPO5, PbLOX1 and PbLOX5 were up-regulated during cold storage, but down-regulated during shelf life. Preharvest treatment with 200 mg/L AVG significantly reduced the consumption of arbutin, chlorogenic acid and total phenols, inhibited the increase of PPO activity along with the expression of PbPAL1, PbPAL2, PbPPO1, PbPPO5 and PbLOX5, and thus effectively reduced core browning in ‘Huangguan’ pear .

In this work, mesoporous HZSM-5 (M-HZSM-5) was synthesized with [gamma]-(2,3-epoxypropoxy) propyltrimethoxysilane as poreexpanding agent through one-pot method and was studied for its catalytic activity and stability in ethanol dehydration. The resultant samples were characterized by various techniques, including Brunauer-Emmett-Teller, Scanning electron microscopy, Fourier transform infrared spectroscopy, the temperature-programmed desorption of N[H.sub.3], and Thermogravimetric. Based on the analysis of the results, M-HZSM-5 with the typical MFI structure displays a specific surface area of 450 [m.sup.2] [g.sup.-1]. Furthermore, the improvement of the activity and anti-coking ability of the catalyst for ethanol dehydration to ethylene is attributed to the existence of mesopores in HZSM-5, which can provide the reaction space and acid sites. Key words: HZSM-5, mesoporous materials, ethanol dehydration Dans le cadre de ces travaux, nous avons synthetise par une methode monotope des zeolithes HZSM 5 mesoporeuses (M HZSM 5) a l'aide du [[gamma] (2,3 epoxypropoxy)-propyl]-trimethoxysilane (EPS) comme agent d'expansion poreuse et nous avons etudie leur activite catalytique et leur stabilite pour effectuer la deshydratation de l'ethanol. Nous avons caracterise les echantillons resultants par diverses techniques, dont la methode de Brunauer-Emmett-Teller (BET), la microscopie electronique a balayage (MEB), spectroscopie infrarouge a transformee de Fourier (FT IR), la desorption thermoprogrammee d'ammoniac (DTP NH3) et la thermogravimetrie (TG). Selon l'analyse des resultats, la zeolithe M HZSM 5 de structure MFI typique affiche une surface specifique de 450 m2/g. De plus, l'amelioration de l'activite et de la capacite anti-cokefaction du catalyseur pour la deshydratation de l'ethanol en ethylene s'explique par l'existence de mesopores dans la zeolithe HZSM 5, qui peuvent constituer des espaces de reaction et fournir des sites acides. [Traduit par la Redaction] Mots-cles : HZSM-5, materiaux mesoporeux, deshydratation de l'ethanol, 1. Introduction Ethylene, as one of the significant feedstocks, is widely used in the synthesis of resin, fiber, and rubber. (1,2) The method of ethylene production includes the thermal cracking [...]

In this work, the corrosion inhibition effects of octadecyl trimethyl ammonium chloride (OTAC) and dioctadecyl dimethyl ammonium chloride (DDAC) on Q235 steel in a 0.5 mol/L H2SO4 solution are studied. The results of the electrochemical experiment, contact angle measurement, and scanning electron microscopy indicate that the two ionic liquids belong to mixed-type corrosion inhibitors with good anti-corrosion performance. Additionally, OTAC has a better anti-corrosion ability than DDAC, implying that the steric hindrance effect of the double alkyl chain is not conducive to the adsorption of DDAC on the electrode surface. [ABSTRACT FROM AUTHOR]

In this article, carbon nanotubes (CNTs) was modified with conducting polymer polyaniline (PANI) to produce composite supporters (PANI-CNTs), and then the MnO2/PANI-CNTs composite material was prepared by hydrothermal route through the oxidation of manganese sulfate using ammonium persulphate (APS) as oxidizing agent. XRD, FT-IR, SEM and laser Raman spectroscopy were used to characterize the composition and structure of materials, meanwhile the electrochemical properties of the material were also investigated. In addition, a series of materials such as MnO2, MnO2-CNTs, MnO2-PANI with different supporters were also prepared to investigated the support effects on the structure and electrochemical properties of composite materials. The characterization results show that the dispersion of MnO2 in composites was greatly affected by the constitution of supports. In comparison with poor MnO2 dispersion on MnO2/CNTs, as for the composite materials including PANI, the anchoring of Mn2+ through covalent bond between PANI and Mn2+, which would help to disperse the MnO2, and then uniform 'starfish-type' MnO2 was achieved on MnO2/PANI-CNTs composite. Moreover, the addition of PANI would improve the conductivity of composite materials. In conclusion, high electrical conductivity and MnO2 dispersion on MnO2/PANI-CNTs composite results in higher specific capacitance (391F/g), which was triple value of specific capacitance for pure MnO2 (132 F/g). Moreover, high specific capacitance retention (90%) for MnO2/PANI-CNTs composite displays good electrochemical stability in comparison with other composites. [ABSTRACT FROM AUTHOR]