摘要 :
A series of surface functionalized silica submicrospheres by distillation-precipitation polymerization were embedded into chitosan (CS) matrix to fabricate the hybrid membranes for direct methanol fuel cell (DMFC). SEM characteriz...
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A series of surface functionalized silica submicrospheres by distillation-precipitation polymerization were embedded into chitosan (CS) matrix to fabricate the hybrid membranes for direct methanol fuel cell (DMFC). SEM characterization indicated that the submicrospheres could disperse homogenously within the CS matrix via tuning the polymer/particle and particle/particle interfacial interactions. The incorporation of sulfonated silica and carboxylated silica led to the reduced fractional free volume (FFV), whereas the incorporation of quaternary aminated silica resulted in increased FFVin the hybrid membranes, which was confirmed by the free volume characteristics analysis using positron annihilation lifetime spectroscopy (PALS). The correlation between methanol crossover and FFV was established: the hybrid membranes with lower FFV displayed higher methanol resistance. Meanwhile, the correlation between the proton acceptor/donor capability and proton conductivity in the hybrid membranes was established. Compared with sulfonated silica and quaternary aminated silica, carboxylated silica possessed the optimum matching in proton acceptor and donor capabilities. Therefore, the membrane embedded with carboxylated silica displayed the highest proton conductivity. In particular, embedding carboxylated silica simultaneously reduced the methanol permeability by 63% and increased the proton conductivity by 40% in comparison with pure CS membrane.
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摘要 :
Online merchant rating is an important determinant of online merchant success, and plays an essential role in building consumer trust. Based on a rich data set collected from Yahoo's merchant review system, we applied content anal...
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Online merchant rating is an important determinant of online merchant success, and plays an essential role in building consumer trust. Based on a rich data set collected from Yahoo's merchant review system, we applied content analysis to identify the most important factors that affect the overall rating of online merchants. We find that consumers in general put more weight on post-transaction services than online-transaction services when they rate online merchants' performance. This research can help e-commerce practitioners understand potentially problematic areas with their business. This research will also provide some easy-to-implement strategies for e-tailing managers to improve their service quality as well as their overall rating in the online feedback systems.
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摘要 :
Experimental drying curves of udon noodles in an air temperature (dry bulb) range of 15 to 65 deg. C and a relative humidity range of 60 to 80/100 were evaluated to develop and appropriate mathematical model to predict the moistur...
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Experimental drying curves of udon noodles in an air temperature (dry bulb) range of 15 to 65 deg. C and a relative humidity range of 60 to 80/100 were evaluated to develop and appropriate mathematical model to predict the moisture content of udon noodles at any time during the air-drying process.
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