Efficient and biologically safe mode of cold atmospheric plasma jet (CAPJ) is crucial for the development of CAPJ-based anticancer therapy. In the experiment and numerical simulations, by changing the pulse duration of a positive-pulsed voltage, we found the optimal CAPJ mode with regular streamer propagation. CAPJ regimes with a maximum discharge current at a temperature T<42 C substantially suppressed the viability of cancer cells. To enhance cell killing, gold nanoparticles (NPs) were added to the cells before and after the CAPJ exposure. Combination of CAPJ, generated with positive pulsed voltage, and gold nanoparticles decreased viability of NCI-H23 epithelial-like lung adenocarcinoma, A549 lung adenocarcinoma, BrCCh4e-134 breast adenocarcinoma and uMel1 uveal melanoma cells. Polyethylene glycol-modified nanoparticles with attached fluorescent label were used to visualize the uptake of NPs. We demonstrated that NPs efficiently entered the cells when were added to the cells just before CAPJ exposure or up to two hours afterwards. The efficiency ofNPs penetration into cells positively correlated with the induced cytotoxic effect: it was maximal when NPs was added to cells right before or immediately after CAPJ exposure. Summarizing, the treatment with optimal CAPJ modes in combination with modified NPs, bearing the cancer-addressed molecules and therapeutics may be next strategy of strengthening the CAPJ-based antitumor approaches.

The flow field studied was eight strongly impinging, radially injected jets, into a non-swirling mainstream flow in a cylindrical duct. Our previous paper (Heat Mass Transf. (2020) 56:2285-2302), showed that asymmetry in the solution is very likely to be an indication of the flow unsteadiness. Also, if the flow is asymmetric, even a time dependent flow solver would not represent the flow correctly if the computational domain is less than the complete cylindrical duct. Thus, the current numerical and topological study was conducted in a 360 degree (complete cylindrical duct) computational domain using a time dependent Unsteady Reynolds-Averaged Navier-Stokes URANS code. Results of this study confirm that the flow of strongly impinging jets is unsteady and asymmetric after the establishment of a regular flow pattern. The asymmetry appears to be cyclic at a frequency of < 2 Hz. Also, the computational fluid dynamics (CFD) results agree with the rules of topological analysis from applied mathematics.

The main goal of this research was to determine the key reagents during the highly Si3N4/SiO2 selective etching. The experiments were conducted, where both Si3N4 and SiO2 samples were etched by NF3/O2 and NF3/O2/N2/H2 plasmas. The sources of the plasmas were removed from the etched sample to exclude a damaging from UV emission and ion bombardment. Optical emission spectroscopy and mass-spectroscopy were used during the etching. The reaction mechanisms were studied using quantum chemistry methods. It was suggested analytical models, which quantitively describe dependence of Si3N4 and SiO2 etch rate on the fluxes of key reactants in NF3/O2 and NF3/O2/N2/H2 downstream plasmas. The densities of the kye reagents were measured and calculated using plasma simulation. Thus, the Si3N4 etch rate curve in NF3/O2 mixture has a peak, where NO density peaks. The high and narrow Si3N4/SiO2 selectivity peaks, which appears in NF3/O2/N2/H2, correlates with high and narrow density peak of vibration excited HF(v1) molecule. Also, this research was aimed to study a mechanism of precursor formation of boron nitride nanotubes growth during high temperature synthesis. It was shown that boron consumption (it is the main impediment to large scale production) occurs through the reactions of N2 dissociative adsorption on small boron clusters (N2 fixation) resulting in generation of B4N4 and B5N4 chains. The liquid boron is only source of the small boron clusters. A subsequent formation of longer chains occurs via collisions of B4N4 and B5N4 with each other. It was also shown that slow gas cooling rate and high pressure enhance liquid boron consumption during the synthesis, creating a good condition to large scale production of high purity and quality BNNT.