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The successful encapsulation of human hepatocellular carcinoma (HepG2) cells would greatly assist a broad range of applications in tissue engineering. Due to the harsh conditions during standard chitosan fiber fabrication processes, encapsulation of HepG2 cells in chitosan fibers has been challenging. Here, we describe the successful wet-spinning of chitosan-alginate fibers using a coaxial flow microfluidic chip. We determined the optimal mixing conditions for generating chitosan-alginate fibers, including a 1:5 ratio of 2% (w∕w) water-soluble chitosan (WSC) solution to 2% (w∕w) alginate solution. Ratio including higher than 2% (w∕w) WSC solution increased aggregation throughout the mixture. By suspending cells in the WSC-alginate solution, we successfully fabricated HepG2 cell-laden fibers. The encapsulated HepG2 cells in the chitosan-alginate fibers were more viable than cells encapsulated in pure alginate fibers, suggesting that cross-linked chitosan provides a better environment for HepG2 cells than alginate alone. In addition, we found that the adhesion of HepG2 cells on the chitosan-alginate fiber is much better than that on the alginate fibers. 相似文献
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Undergraduate subjects taught identifying traits of animals (fish, reptiles, amphibians, mammals) to a fifth grade student confederate over a microphone. Subjects were randomly assigned to one of four conditions in which they failed (F) or succeeded (S) in teaching five animal comparison problems. The four conditions were (a) F, S, S, S, S; (b) F, F, F, S, S; (c) S, F, F, F, S; and (d) S, S, S, F, S. The teaching sessions were tape recorded and analyzed for Teaching Time, Word Rate, and Voice Amplitude. Analyses revealed increased Teaching Time and decreased Word Rate following failure. Voice Amplitude increased across teaching sessions independent of success or failure. Findings were interpreted as more consonant with frustration-aggression than frustrative nonreward energizing theory. 相似文献