A two-step process was used to synthesize the high molecular weight poly (lactic acid) using thionyl chloride as an activator for the polycondensation of prepolymer of lactic acid. The products were characterized by G...A two-step process was used to synthesize the high molecular weight poly (lactic acid) using thionyl chloride as an activator for the polycondensation of prepolymer of lactic acid. The products were characterized by GPC, DSC, and 1H-NMR. Poly (L-lactic acid) (PLLA) with molecular weight Mw: 32875 was obtained when thionyl chloride was used, while low molecular weight PLLA Mw: 7350 was yielded without thionyl chloride. Effects of the concentration of thionyl chloride, polymerization time and bases on the molecular weight of poly (lactic acid) were investigated. In DSC scans the glass transition temperatures (Tg) of the resulting polymers varied from 25.3 to 57.6℃, and the Tg of poly(L-lactic acid) was higher than that of poly (D,L-lactic acid) (PDLLA). The melting points of poly (L-lactic acid) and poly (D, L-lactic acid) could not be found unless the polymers were obtained by thionyl chloride activator.展开更多
Fermented chile pepper mash （Capsicum annuum cv. Mesilla Cayenne） is a major industrial food product in New Mexico. The fermentation of chile pepper mash depends on temperature, acidity, salt concentration, dissolve...Fermented chile pepper mash （Capsicum annuum cv. Mesilla Cayenne） is a major industrial food product in New Mexico. The fermentation of chile pepper mash depends on temperature, acidity, salt concentration, dissolved air, available carbohydrates and enzymes. The objective of this study was to evaluate the effects of the addition of calcium chloride （CaCI2） on the microbial characteristics of the pepper mash fermentation. Nine five gallon buckets were prepared with pepper that had been washed and ground by the manufacturer, each with 15% sodium chloride added. The buckets were allotted randomly to 1 of 3 treatments. The treatments included no CaCl2, 0.2% CaCl2 and 0.4% CaCl2 added to the pepper mash. Samples were stored at room temperature and sampled over a 3 months period to examine changes in the microflora. Chile mash samples were serially diluted in butterfield＇s phosphate buffer for microbial enumeration. Aerobic plate counts were conducted by pour plating with an overlay. Petrifilms were used for E. coil/coliform counts and Enterobacteriaceae. Yeasts and molds were surface plated on Rose Bengal Chloramphenicol agar while streptococci and lactobacilli were plated onto M17 and acidified MRS respectively. Aerobic plate counts, coliforms, E. coli, Enterobacteriaceae, yeast, mold, lactobacilli, and streptococci were not affected by CaCl2 level. The addition of 0.4% CaCl2 was found to have no effect on the chile pepper mash fermentation.展开更多
The authors prepared,characterized and preliminary studied the properties of some neoteric solvents-ionic liquids based on choline chloride,i.e.,three ionic liquids based on the eutectics of choline chloride（2-hydrox...The authors prepared,characterized and preliminary studied the properties of some neoteric solvents-ionic liquids based on choline chloride,i.e.,three ionic liquids based on the eutectics of choline chloride（2-hydroxyN,N,N-trimethylethanaminium chloride） with,respectively,urea,malonic acid and citric acid.The obtained mixtures were clear and colorless ionic liquids at room temperature.The thermophysical properties,namely,density,viscosity,and electrical conductivity of these mixtures were investigated as a function of temperature within a range of 298-353 K.Correlations for the temperature dependence of the measured properties were generated and discussed in terms of Arrhenius theory.Finally the electrochemical windows of the eutectic liquids were determined.展开更多
基金National Science Foundation of China (2977 6035)
文摘A two-step process was used to synthesize the high molecular weight poly (lactic acid) using thionyl chloride as an activator for the polycondensation of prepolymer of lactic acid. The products were characterized by GPC, DSC, and 1H-NMR. Poly (L-lactic acid) (PLLA) with molecular weight Mw: 32875 was obtained when thionyl chloride was used, while low molecular weight PLLA Mw: 7350 was yielded without thionyl chloride. Effects of the concentration of thionyl chloride, polymerization time and bases on the molecular weight of poly (lactic acid) were investigated. In DSC scans the glass transition temperatures (Tg) of the resulting polymers varied from 25.3 to 57.6℃, and the Tg of poly(L-lactic acid) was higher than that of poly (D,L-lactic acid) (PDLLA). The melting points of poly (L-lactic acid) and poly (D, L-lactic acid) could not be found unless the polymers were obtained by thionyl chloride activator.
基金Supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (2015BAD16B01)Tianjin Key Technology Research and Development Support Program (13ZCDNC01900)
文摘Fermented chile pepper mash （Capsicum annuum cv. Mesilla Cayenne） is a major industrial food product in New Mexico. The fermentation of chile pepper mash depends on temperature, acidity, salt concentration, dissolved air, available carbohydrates and enzymes. The objective of this study was to evaluate the effects of the addition of calcium chloride （CaCI2） on the microbial characteristics of the pepper mash fermentation. Nine five gallon buckets were prepared with pepper that had been washed and ground by the manufacturer, each with 15% sodium chloride added. The buckets were allotted randomly to 1 of 3 treatments. The treatments included no CaCl2, 0.2% CaCl2 and 0.4% CaCl2 added to the pepper mash. Samples were stored at room temperature and sampled over a 3 months period to examine changes in the microflora. Chile mash samples were serially diluted in butterfield＇s phosphate buffer for microbial enumeration. Aerobic plate counts were conducted by pour plating with an overlay. Petrifilms were used for E. coil/coliform counts and Enterobacteriaceae. Yeasts and molds were surface plated on Rose Bengal Chloramphenicol agar while streptococci and lactobacilli were plated onto M17 and acidified MRS respectively. Aerobic plate counts, coliforms, E. coli, Enterobacteriaceae, yeast, mold, lactobacilli, and streptococci were not affected by CaCl2 level. The addition of 0.4% CaCl2 was found to have no effect on the chile pepper mash fermentation.
文摘The authors prepared,characterized and preliminary studied the properties of some neoteric solvents-ionic liquids based on choline chloride,i.e.,three ionic liquids based on the eutectics of choline chloride（2-hydroxyN,N,N-trimethylethanaminium chloride） with,respectively,urea,malonic acid and citric acid.The obtained mixtures were clear and colorless ionic liquids at room temperature.The thermophysical properties,namely,density,viscosity,and electrical conductivity of these mixtures were investigated as a function of temperature within a range of 298-353 K.Correlations for the temperature dependence of the measured properties were generated and discussed in terms of Arrhenius theory.Finally the electrochemical windows of the eutectic liquids were determined.
