Nano-sized CeO_2 powders were synthesized by homogeneous precipitation method in alcohol-water solution with HMT as precipitator and the nano-particles were characterized by TEM and BET. The process parameters which i...Nano-sized CeO_2 powders were synthesized by homogeneous precipitation method in alcohol-water solution with HMT as precipitator and the nano-particles were characterized by TEM and BET. The process parameters which influenced the sizes and agglomeration of nanometer CeO_2 powders were studied and the influence mechanism was discussed. The results show that the average size of the particles prepared by the above method with the best process parameters is about 8 nm, and the particles are of smaller size and better dispersion than those obtained from the ordinary powders synthesized by homogeneous precipitation in water solution.展开更多
Objective:To optimize the technological conditions of ultrasonic-assisted extraction of Amomum longiligulare T.L.Wu polysaccharides and increase the yield of polysaccharides.Methods:The polysaccharide was prepared by ...Objective:To optimize the technological conditions of ultrasonic-assisted extraction of Amomum longiligulare T.L.Wu polysaccharides and increase the yield of polysaccharides.Methods:The polysaccharide was prepared by water extraction and alcohol precipitation method,and the yield of polysaccharide was taken as an index.The effects of ultrasonic time,extraction times,ultrasonic temperature,and water-to-material ratio on polysaccharide yield were investigated through a single factor experiment.Combined experimental design and response surface analysis were used to optimize the extraction process of Amomum longiligulare T.L.Wu polysaccharides.Results:The optimum conditions of ultrasonic-assisted extraction were determined as follows:extraction time of 29 min,three extraction times,water bath extraction temperature of 68℃,water-to-material ratio of 15:1;under these conditions,the polysaccharide yield was 10.69%.Conclusion:The results are close to the predicted values of the model.This optimization test is effective and feasible,and provides a reference for the related research of Amomum longiligulare T.L.Wu.展开更多
文摘Nano-sized CeO_2 powders were synthesized by homogeneous precipitation method in alcohol-water solution with HMT as precipitator and the nano-particles were characterized by TEM and BET. The process parameters which influenced the sizes and agglomeration of nanometer CeO_2 powders were studied and the influence mechanism was discussed. The results show that the average size of the particles prepared by the above method with the best process parameters is about 8 nm, and the particles are of smaller size and better dispersion than those obtained from the ordinary powders synthesized by homogeneous precipitation in water solution.
基金National Natural Science Foundation of China(No.81660649)Hainan Medical College Student Innovation and Entrepreneurship Training Program Project(No.201811810007)。
文摘Objective:To optimize the technological conditions of ultrasonic-assisted extraction of Amomum longiligulare T.L.Wu polysaccharides and increase the yield of polysaccharides.Methods:The polysaccharide was prepared by water extraction and alcohol precipitation method,and the yield of polysaccharide was taken as an index.The effects of ultrasonic time,extraction times,ultrasonic temperature,and water-to-material ratio on polysaccharide yield were investigated through a single factor experiment.Combined experimental design and response surface analysis were used to optimize the extraction process of Amomum longiligulare T.L.Wu polysaccharides.Results:The optimum conditions of ultrasonic-assisted extraction were determined as follows:extraction time of 29 min,three extraction times,water bath extraction temperature of 68℃,water-to-material ratio of 15:1;under these conditions,the polysaccharide yield was 10.69%.Conclusion:The results are close to the predicted values of the model.This optimization test is effective and feasible,and provides a reference for the related research of Amomum longiligulare T.L.Wu.