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Nanoscale polymer particles produced by immersion electrospraying
Shichen Li,Bong-Kee Lee(이봉기) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.6
The present study outlines a novel method for fabricating polymer nanoparticles using immersion electrospraying. Electrospraying is considered one of the most commonly used methods to manufacture polymer nanoparticles because of its simplicity and scalability. In immersion electrospraying, which is an advanced variant of the typical electrospraying process, both the nozzle and collector are placed in a liquid. This unique configuration, which is very different from the typical case, leads to a different mechanism directly associated with the nanoparticle’s morphology. Therefore, it is expected that the polymer nanoparticles with unique shapes can be fabricated by immersion electrospraying. However, in-depth studies on the product morphology in immersion electrospraying have been rarely conducted. In this regard, this study investigates the morphological characteristics of polymer nanoparticles produced by immersion electrospraying. Similar to the typical electrospraying case, the concentration of the polymer solution is considered the significant factor determining the nanoparticle morphology. From the experiments, it is found that the aggregated nanoparticles are formed during immersion electrospraying, which is hard to be found in typical cases. In addition, the produced polymer nanoparticles become more aggregated with increasing polymer concentration. However, there is no significant change in the size of polymer nanoparticles. The present result shows the feasibility of immersion electrospraying in producing polymer nanoparticles with peculiar shapes. [그림 본문 참조]
Shichen Li,Hanghai Zhou,Chunlei Chen,Feng Zeng,Gang Zheng,Xingpeng Wang,Chunfang Zhang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4
A laboratory-scale study was conducted to investigate the effect of rhamnolipids (RLs) supplement on the amelioration of saline-alkali soils. The RLs supplement improved the soil aggregates stability and promoted the formation of macro-aggregates which increased by up to 10.84% and 15.92% in alkaline soil and saline soil, respectively. In addition, RLs amendment led to a pH reduction from initial 8.87 to 7.80-7.84 in alkaline soil, and a salt rejection up to 20.72% in saline soil, remarkably alleviating the saline-alkali stress on microorganisms and plants. Meanwhile, microbial growth and activity as well as the seed germination performance were greatly improved in both types of soil. Furthermore, RLs addition greatly altered the microbial community structure and supported the proliferation of bacterial species (e.g., Pseudomonas oleovorans, Pseudomonas stutzeri, and Alcanivorax dieselolei) that favored the improvement of soil properties and nutrients circulation, thus markedly enhancing the microecological functions including carbon and nitrogen metabolisms. Further supplement of γ-PGA only exhibited promoting effect on aggregates formation and microbial growth and activity. The findings obtained in this study prove the application of RLs as a promising approach for saline-alkali soil amelioration.
( Shichen Li ),( Bong-kee Lee ) 한국센서학회 2021 센서학회지 Vol.30 No.3
In this study, the degree of alignment of polymer microfibers produced by electrospinning using a rotating water collector was evaluated. Aligned micro- and nano-fibers are required in various practical applications involving anisotropic properties. The degree of fiber alignment has many significant effects; hence, and accurate quantitative analysis of fiber alignment is necessary. Therefore, this study developed a simple and efficient method based on two-dimensional fast Fourier transform, followed by ellipse fitting. As a demonstrative example, the polymer microfibers were electrospun on the rotating water collector as the alignment of microfibers can be easily controlled. The analysis shows that the flow velocity of the liquid collector significantly affects the electrospun microfiber alignment, that is, the higher the flow velocity of the liquid collector, the greater is the degree of microfiber alignment. This method can be used for analyzing the fiber alignment in various fields such as smart sensors, fibers, composites, and textile engineering.