A 2D drift diffusion fluid model was employed to study the plasma uniformity of different capacitively coupled plasma (CCP) in argon discharges based on the COMSOL platform. The numerical results show that compared with the traditional CCP device that discharges between plates, the plasma uniformity of CCP device discharge by inner capacitors (CCP-ICD) has been significantly improved overall. Then, the influence of the number of capacitors and the capacitor spacing on the plasma uniformity of CCP-ICD was analyzed. The plasma uniformity can reach 89.5% in the radial direction under the best parameters, but the electron number density is reduced by an order of magnitude. In order to obtain a CCP source with high density and better uniformity, a new multi-directional source CCP-ICD was designed and numerically analyzed. The simulation results show that the new multi-directional source CCP-ICD can improve the uniformity in both radial and axial directions by about 40% without reducing the plasma density. The above conclusions show that the multi-directional source CPP-ICD device designed in this paper has great application prospects in the microelectronic and semiconductor industries.

In this study, polylactic acid (PLA)/sulfadiazine sodium/proteinase K composite nanofibers were prepared by electrospinning, and their morphology was observed by scanning electron microscope. The novel nanofibers were characterized by Fourier transform infrared spectroscopy and drug release curve. The activity of different groups of drugs loaded nanofibers in frostbite wound of rats was studied and compared with the blank control group. Hematoxylin-eosin staining and transmission electron microscope were used to access the histological changes of frostbite wounds on the back of rats before and after treatment.CD31 fluorescence staining was used to track the reconstruction and improvement of blood vessels in tissues. The results revealed that the drug release rate of PLA/sulfadiazine sodium/proteinase K nanofibers group was more than 50% at 1 h, and the cumulative drug release rate was more than 88% at 168 h, and CD31 fluorescence showed that its vascular density was 13.27% ± 0.9%, which was significantly higher than that of other groups. Therefore, PLA/sulfadiazine sodium/proteinase K composite nanofibers could promote the healing of frostbite wounds, which indicated the increase of capillaries and the regeneration of hair follicles. PLA/sulfadiazine sodium/proteinase K composite nanofibers have great potential in the application of frostbite.

In recent years, the interaction of electromagnetic waves (EM) with plasma sources under argon and helium discharges has been extensively studied due to its potential applications in plasma stealth. However, nitrogen, as a more economical discharge gas, has been ignored in terms of its absorption of EM waves and stealth effect. In this work, a numerical calculation model combining two-dimensional capacitively coupled plasma (CCP) fluid model and EM wave model was developed to investigate the plasma uniformity degree and broadband microwave absorption effects in helium and nitrogen CCP. It is concluded that the two-dimensional model in this paper has more accurate and reasonable through comparison with the one-dimensional and experimental results in helium CCP. Nitrogen CCP shows better broadband absorption effects than that of helium, and helium plasma has better uniformity than nitrogen under the same discharge parameters. But the uniformity degree of nitrogen plasma is not much different from that of helium under the same electron density, which means that nitrogen can significantly improve its broadband wave absorption properties to some extent without loss of uniformity degree. Based on the above conclusions, the absorption characteristics of nitrogen CCP under different radio frequency (RF) power and pressure are analyzed. The attenuation effect of nitrogen CCP increases with the increasing RF power, and it is interesting that the influence of pressure on the attenuation of EM waves is not monotonically increasing, and the related mechanism is discussed. Finally, discussion of skin depth under different RF power and pressure validates the above conclusions. The absorption band of nitrogen CCP under the best parameters in this work can reach the X-band, which shows great application potential in plasma stealth.

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