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Study on the Trajectory of Free-End Fiber in Jet Vortex Spinning Based on the Elastic Thin-Rod Finite Element Model of Flexible Fiber

100%

Han C. , Gao W. , Chen L.

tom Vol. 20, no. 1

43--48

During the air flow twisting process of jet vortex spinning, the moving characteristics of flexible free-end fiber are complex. In this paper, the finite element model of the fiber is established based on elastic thin rod element. According to the air pressure and velocity distribution in the airflow twisting chamber of jet vortex spinning, this paper analyzes the undetermined coefficients of the finite element kinetic differential equation of the free-end fiber following the principle of mechanical equilibrium, energy conservation, mass conservation and momentum conservation. Based on numerical simulation, this paper gets the trajectory of the free-end fiber. Finally, the theoretical result of the free-end fiber trajectory by finite element simulating is tested by an experimental method. This paper has proposed a new method to study the movement of the fiber and learn about the process and principle of jet vortex spinning.

Composition of norfloxacin-resistant bacteria and isolation of norfloxacin-degrading bacteria in subtropical aquaculture ponds in China

75%

Mao L. , Chen L. , Wang X. , Xu Z. , Ouyang H. , Huang B. , Zhou L.

tom Vol. 48, no. 4

95--101

To analyze the composition of norfloxacin-resistant bacteria and norfloxacin-degrading bacteria in pond water and sediment in subtropical China, the composition of antibiotic resistant bacteria in pond water and sediment enriched with norfloxacin-containing medium was analyzed by high-throughput sequencing. Sediment and water samples were collected from 3 fish ponds in subtropical China, and domesticated with norfloxacin, subsequently norfloxacin-resistant bacteria through high-throughput sequencing of 16S rDNA, and isolated norfloxacin--degrading bacteria. Our results showed that the pond sediment and water contain a variety of norfloxacin-resistant bacteria, mainly from Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, and Chloroflexi. Moreover, we isolated two norfloxacin-degrading bacteria (NorXu-2 and NorXu-3). The norfloxacin-degrading rate by NorXu-2 and NorXu-3 in the culture mediums with 200 μg/mL was the highest, which was up to 49.71% and 35.79%, respectively. When the norfloxacin concentration was 200 μg/mL, NorXu-2 and NorXu-3 had the best norfloxacin- -degrading effect at pH of 6, and the degradation rates were 53.64% and 45.54%, respectively. Moreover, NorXu-3 exhibited a good tolerance to high NaCl concentration. These results not only provided basic data for the follow-up study of the molecular mechanism of antimicrobial microbial degradation, but also provided potential norfloxacin degrading bacteria for norfloxacin removal and bioremediation in aquaculture environment.