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Structurally natural chitosan films decorated with Andrographis paniculata extract and selenium nanoparticles: Properties and strawberry preservation

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FOOD BIOsciENCE 2023年第3期53卷 1630-1640页

作者： Huong, Quach Thi Thanh Nam, Nguyen Thanh Hoai Duy, Bui Thanh An, Hoang Hai, Nguyen Duy Ngan, Hoang Thuy Kim Ngan, Lam Thanh Nhi, Tran Le Hoai Linh, Dang Thi Yen Khanh, Tran Nhat Thu, Dang Vu Anh Nguyen, Huu Hieu Ho Chi Minh City univ Technol HCMUT Key Lab Chem Engn & Petr Proc Key CEPP Lab VNU HCM 268 Ly Thuong Kiet StDist 10 Ho Chi Minh City Vietnam Ho Chi Minh City univ Technol HCMUT Fac Chem Engn 268 Ly Thuong Kiet StDist 10 Ho Chi Minh City Vietnam Vietnam Natl univ Ho Chi Minh City Linh Trung Ward Ho Chi Minh City Vietnam univ sci hcmus vnu 227 Nguyen CuDist 5 Ho Chi Minh City Vietnam

In this study, selenium nanoparticles (SeNPs) were synthesized using Annona glabra leaf extract as a reducing agent. In addition, the solution-casting method was employed to prepare the food preservation film from the chitosan-Andrographis paniculata extract-selenium nanoparticles (CS-APE-Se). The effects of SeNPs with different contents (equivalent to 1, 2, 3, and 4% of chitosan mass) on fundamental properties and bioactivities of the films were also tested. According to the results, the prepared films possess good biodegradability after 30 days of burial. Besides, the antioxidant activity of the material was also investigated via free radical scavenging toward 2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2 '-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), which showed the inhibition rate up to 45 and 82%, respectively. Additionally, the antibacterial performance of the films was assessed against Staphylococcus aureus and Pseudomonas aeruginosa, which indicated the highest antibacterial capacity with the inhibition diameter of 18.1 +/- 0.03 and 19.25 +/- 0.01 mm, respectively. Furthermore, the coating of the CS-APE-Se films also effectively prevented physical damage and prolonged the shelf life of the strawberries by up to 10 days. The aforementioned results demonstrated the potential for applying chitosan (CS) film in combination with Andrographis paniculata leaf extract and SeNPs as a secure alternative to the harmful chemicals currently used in food preservation.

关键词： Chitosan Food packing Andrographis paniculata Selenium nanoparticles

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Thermodynamic Behavior of Manganese and Phosphorus between Liquid Iron and CaO-MgO-SiO_2-Al_2O_3-Fe_tO-MnO-P_2O_5 Slags

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Journal of university of science and Technology Beijing 2001年第3期8卷 171-176页

作者： Bo Song, Seon-Hyo Kim, Jinghong Mao, Qing Lin Metallurgy School, university of science and Technology Beijing, Beijing 100083, China Department of Materials science & Engineering, Pohang university of science & Technology, Pohang 790-784, Korea Material S univ sci & Technol Beijing Met Sch Beijing 100083 Peoples R China Pohang univ sci & Technol Dept Mat Sci & Engn Pohang 790784 South Korea univ sci & Technol Beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-Al2O3-FetO-MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron containing Mn and P and the ladle slag at 1873 K. The Mn distribution ratio L-Mn increases with increasing FetO content and decreasing the basicity ((%CaO + %MgO)/(%SiO2 + %Al2O3 + %P2O5)) in slag, while the P distribution ratio Lp seems to be increased as FetO content and the basicity increases. The values of L-Mn and L-p decrease by the addition of Al2O3 into slag. The expression of the dependence of L-Mn and L-p on the basicity and FetO content in slag was obtained.

关键词： manganese phosphorus liquid iron ladle slag thermodynamic behavior

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REACTION MECHANISM OF BENZOPHENONE-PHOTOINITIATED CROSSLINKING OF POLYETHYLENE

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Chinese Journal of Polymer science 2002年第4期20卷 291-307页

作者： Bao-jun Qu State Key Laboratory of Fire science and Department of Polymer science and Engineering university of science and Technology of China Hefei 230026 China univ sci & Technol China State Key Lab Fire Sci Hefei 230026 Peoples R China univ sci & Technol China Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The radical intermediates, the crosslink microstructures, and the reaction mechanism of benzophenone (BP)-photoinitiated crosslinking of low-density polyethylene (LDPE) and model compounds (MD) have been reviewed in detail. The spin-trapping electron spin resonance (ESR) spectra obtained from the LDPE/BP systems with spin-trap agents show that two kinds of polymer radical intermediates are mainly formed: tertiary carbon and secondary carbon radicals. The spin-trapping ESR studies of MD/BP systems give further evidence that photocrosslinking reactions of PE predominantly take place a sites of tertiary carbon, secondary carbon, and especially allylic carbon when available. The high resolution C-13-NMR spectra obtained from LDPE and MD systems show that the crosslink microstructures have H- and Y-type links and that their concentrations are of the same order. The fluorescence, ESR, C-13 and H-1-NMR spectra from the PE and MD systems demonstrate that the main photoreduction product of BP (PPB) is benzpinacol formed by the recombination of two diphenylhydroxymethyl (K-.) radical intermediates. Two new PPB products: an isomer of benzpinacol with quinoid structure, 1-phenylhydroxymethylene-4-diphenylhydroxymethyl-2,5-cyclobexadiene and three kinds of alpha-alkyl-benzhydrols have been detected and identified. These results provide new experimental evidence for elucidating the reaction mechanism in the BP-photoinitiated crosslinking of polyethylene.

关键词： photocrosslinking mechanism polymer radical intermediates crosslink microstructures photolytic products of benzophenone polyethylene model compound

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Bright soliton dynamics for resonant nonlinear Schrödinger equation with generalized cubic-quintic nonlinearity

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CHINESE PHYSICS B 2024年第12期33卷 278-288页

作者： Bao, Keyu Tang, Xiaogang Wang, Ying Jiangsu univ sci & Technol Sch Sci Jiangsu 212100 Zhenjiang Peoples R China

For systems modeled by the resonant nonlinear Schr & ouml;dinger equation (RNLSE) with generalized cubic-quintic nonlinearity, we derive the bright soliton solution of the equation in (1+1) dimensions, using the modified F-expansion method along with the novel ansatz of F-base function. Furthermore, we extend the analytical study of soliton dynamics to higher (2+1) and (3+1) dimensions by using the self-similar method, and demonstrate the soliton behavior via graphical illustration. Moreover, we investigate the effect of the resonance term on bright soliton solution in (1+1) dimensions. Additionally, we consider the nonlinear equation models with perturbation terms and derive the bright soliton solutions for the one-dimensional (1D) to three-dimensional (3D) cases. The theoretical results derived can be used to guide the experimental studies and observations of bright solitons in systems described by RNLSE model.

关键词： soliton resonant nonlinear Schr & ouml dinger equation F-expansion method 42.65.Tg 42.81.Dp 02.30.Jr 42.50.Md

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Effect of the Fourth Element on Bonding of Silicon Nitride Ceramics with Y_2O_3-Al_2O_3-SiO_2 Glass Solders

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Journal of Rare Earths 2001年第2期19卷 90-96页

作者：周飞 Jiangsu univ sci & Technol Sch Mat Sci Zhejiang 212013 Peoples R China

Bonding of Si 3N 4 ceramic was performed with Y 2O 3 Al 2O 3 SiO 2(YAS) X glass solders,which were mixed with TiO 2 (YT) and Si 3N 4 (YN), respectively. The effects of bonding conditions and interfacial reaction on the joint strength were studied. The joint strength in different bonding conditions was measured by four point bending tests. The interfacial microstructures were observed and analyzed by SEM, EPMA and XRD. It is shown that with the increase of bonding temperature and holding time, the joint strength increases reaching a peak, and then decreases. When TiO 2 is put into YAS solder,the bonding interface with Si 3N 4/(Y Sialon glass+TiN)/TiN/Y Sialon glass is formed. When YAS solder is mixed with Si 3N 4 powder, the interfacial residual thermal stress may be decreased, and then the joint strength is enhanced. According to microanalyses, the bonding strength is related to interfacial reaction.

关键词： rare earths Si 3N 4 ceramic yttria titanium oxide oxynitride glass bonding

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Aging Characteristics, Stress Corrosion Behaviour and Role of Mg Segregation at Grain Boundary in 7175High-strength Al Alloy

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Journal of Materials science & Technology 1998年第3期14卷 259-264页

作者： Song, Renguo Geng, Ping Zeng, Meiguang Zhang, Baojin Northeastern univ Coll Sci Dept Mat Sci Shenyang 110006 Peoples R China

The aging characteristics, stress corrosion behavior and chemical composition of grain boundary in 7175 high-strength Al alloy during long term aging process have been investigated by hardness measurement, constant elongation rate testing (CERT) and energy spectroscopy analysis. The results indicate that double peaks in aged state feature the hardness and strength of 7175 Al alloy. Although the intensity of double peaks is almost equal, the stress corrosion resistance in the second peak-aged state is better than that of the first peak-aged state. The effects of Mg segregation on the binding energy of grain boundary have been calculated by using free electron theory developed in this paper. The results showed that Mg segregation plays a significant role in controlling stress corrosion susceptibility, which is consistent with the experimental results. (Edited author abstract) 32 Refs.

关键词： Aluminum alloys

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Microstructural Features During Strain Induced Ferrite Transformation in 08 and 20Mn Steels

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Journal of university of science and Technology Beijing 2001年第2期8卷 105-110页

作者： Ping Yang, Feng-e Cui, Fuming Wang (Materials science and Engineering School, university of science and Technology Beijing, Beijing 100083, China) (Metallurgy School, university of science and Technology Beijing, Beijing 100083, China) univ sci & Technol Beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China univ sci & Technol Beijing Met Sch Beijing 100083 Peoples R China

The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 20Mn steels. The influences of carbon equivalence and initial austenite grain size on ferrite grain refinement and the volume fraction of ferrite during straining were inspected. The results revealed that the accelerating effect of ferrite transformation by strain was increased as the carbon equivalence decreased. However, finer ferrite grains were obtained at higher carbon content. At strain of similar to1.5 ferrite grains less than 3 mum and 2 mum can be obtained in 08 and 20Mn steels respectively. Whereas the ferrite grain refinement in 08 steel was due to both effects of strain induced transformation and ferrite dynamic recrystallization, that in 20Mn was mainly due to strain induced transformation. Heavy strain can produce fine ferrite grains in coarse austenite grained 08 steel, but it would lead to band microstructure in coarse austenite grained 20Mn.

关键词： clean carbon steel strain induced transformation grain refinement ferrite dynamic recrystallization

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Bonding of Silicon Nitride Ceramic Composite with RE_2O_3Al_2O_3SiO_2 Glass Solders

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Journal of Rare Earths 1999年第3期17卷 194-199页

作者：周飞李志章罗启富 Jiangsu univ sci & Technol Dept Mat Sci & Engn Zhenjiang 212013 Peoples R China Zhejiang univ Dept Mat Sci & Engn Hangzhou 310027 Peoples R China

Liquid bonding of Si 3N 4 ceramic composite was carried out with RE 2O 3 Al 2O 3 SiO 2 glass solders. The effect of bonding conditions and interfacial reaction on the joint strength was studied. The joint strength under different bonding conditions was measured by four point bending tests. The interfacial microstructures were observed and analyzed by SEM, EPMA and XRD. It is shown that the liquid glass solders react with Si 3N 4 at interface, forming the Si 3N 4/Si 2N 2O/Y(La) sialon glass/Y(La) sialon glass gradient interface. With the increase of bonding temperature and holding time, the joint strength first increased reaching a peak, and then decreased. According to microanalyses, LaYO 3 precipitated from joint glass improves joint strength at room and high temperature.

关键词： Rare earths Si 3N 4 ceramic composite Lanthana Yttria Bonding

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A NEW SYNERGIST FOR INTUMESCENT FLAME RETARDANT POLYPROPYLENE

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Chinese Journal of Polymer science 2002年第4期20卷 377-380页

作者： Qiang Wu Bao-jun Qu State Key Laboratory of Fire science and Department of Polymer science and Engineering university of science and Technology of China, Hefei 230026 China univ sci & Technol China State Key Lab Fire Sci Hefei 230026 Peoples R China univ sci & Technol China Dept Polymer Sci & Engn Hefei 230026 Peoples R China

The synergistic effects of silicotungstic acid (SiW12) as a catalyst in the phosphorus-nitrogen compounds AM-based intumescent flame-retardant (IFR) polypropylene (PP) were studied using the limiting oxygen index (LOI), the UL-94 test, thermogravimetric analysis (TGA), real time Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS). The LOI data show that SiW12 added to PP/IFR systems has a synergistic FR effect with an IFR additive named AM. The TGA data show that SiW12 apparently increases the thermal stability of the PP/IFR systems at high temperature (T > 500degreesC). The FTIR results provide the positive evidence that IFR can improve the thermal stability of PP and SiW12 can induce a higher rate of formation of phosphoric acid and its derivatives. The LRS measurements provide useful information on the carbonaceous microstructures. In short, a suitable amount of SiW12 (1.5 wt%) exerts synergistic effects with the IFR by increasing the LOI value and the thermal stability at high temperature and promoting the formation of charred structures on the burning PP surface.

关键词： silicotungistic acid synergistic effect intumescent flame retardant polypropylene

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Predication of Plastic Flow Characteristics in Ferrite/Pearlite Steel Using a Fern Unit Cell Method

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上海交通大学学报 2004年第z2期38卷 61-66页

作者： Hong Li Jingtao Han Jing Liu Lv Zhang School of Material sci. & Eng. Univ. Of Sci. &Tech. Beijing Beijing100083 China School of Material Sci. & Eng. Univ. Of Sci. &Tech. Beijing Beijing100083 China School of Material Sci. & Eng. Univ. Of Sci. &Tech. Beijing Beijing100083 China School of Material Sci. & Eng. Univ. Of Sci. &Tech. Beijing Beijing100083 China

The flow stress of ferrite/pearlite steel under uni-axial tension was simulated with finite element method (FEM) by applying commercial software MARC/MENTAT. Flow stress curves of ferrite/pearlite steels were calculated based on unit cell model. The effects of volume fraction, distribution and the aspect ratio of pearlite on tensile properties have been investigated.

关键词： ferrite/pearlite steel unit cell flow curve finite element method simulation

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