Low-temperature plasma applications and diagnostics
Remotely Floating Wire-Assisted Generation of High-Density Atmospheric Pressure Plasma and SF6-Added Plasma Etching of Quartz Glass
High-density, large-volume atmospheric pressure-inductively coupled plasma sources with different geometrical designs were developed using the floating wire that is able to increase the electric field beyond that of the breakdown threshold, resulting in an ignition at low supplied powers.
Thi-Thuy-Nga Nguyen, Kenji Ishikawa et al. Journal of Applied Physics 125 (6), 063304 (pp. 1-11) (February 14, 2019). link
Systematic diagnostics of the electrical, optical, and physicochemical characteristics of low-temperature atmospheric-pressure helium plasma sources
Two plasma sources were assessed by examining three primary aspects, (i) electrical, (ii) plasma parameters, (iii) levels of gas-phase oxygen atoms and liquid-phase radicals. As the time-averaged electrical currents flowing to the target and the amount of liquid phase OH radicals showed a large difference, especially when the plume made contact with the target.
Keigo Takeda, Kenji Ishikawa et al. Journal of Physics D:Applied Physics 52 (16), 165202 (pp. 1-13) (February 15, 2019). link
Liquid dynamics in response to an impinging low-temperature plasma jet
Atmospheric-pressure plasma jets (APPJ) generate a variety of reactive oxygen and nitrogen species (RONS) while maintaining a low gas temperature. An increase in liquid flow velocities and circulation size was observed in the liquid bath as a result of increased jet impact force and additional shear across the liquid surface, evidenced by the increase in cavity size and the increase in jet adherence to the liquid surface as seen by schlieren imaging. The acidification of the solution was independent of buffers during plasma treatment, and helium-only treatments basified the solution through evaporation and ensuing increase in buffer concentrations.
Timothy R. Brubaker, Kenji Ishikawa et al. Journal of Physics D: Applied Physics 52 (7), 075203 (pp. 1-11) (February 13, 2019). link
Electronic properties and primarily dissociation channels of hydrofluoroethane compounds
Electronic properties of fluoroethane compounds were investigated using computational chemistry. Primary dissociation channels in the process plasma for fluoroethane compounds are revealed that C–C bond scission occurred by excitation and ionization and C–F bond scission occurred by excitation and electron attachment.
Toshio Hayashi, Kenji Ishikawa et al. Japanese Journal of Applied Physics 58 (SE), SEEF01 (pp. 1-18) (May 1, 2019). link
Nonthermal plasma-activated medium (PAM) modified metabolomic profiles in glycolysis of U251SP glioblastoma
Plasma activated medium (PAM) induced PAM-specific apoptotic cell-death. PAM inhibits the glycolysis pathway and enhances the pentose phosphate pathway in U251SP glioblastoma cells. Metabolomic profile of U251SP glioblastoma cells analyzed using capillary electrophoresis mass spectrometry (CE-MS).
Naoyuki Kurake, Kenji Ishikawa et al. Archives of Biochemistry and Biophysics 662, pp.83-92 (February 15, 2019). link
Gene expression of osteoblast-like cells on carbon nanowall as scaffolds during incubation with electrical stimulation
Osteoblast-like cells (Saos-2) were enhanced in proliferation when they were incubated in the presence of electrical stimulation (ES) on nanostructured cell-culture scaffolds of carbon nanowalls (CNWs) with the wider average wall-to-wall distance of 220 nm. Differentiation gene expression levels of Runt-related transcription factor 2 (Runx2) and osteocalcin (OC) were suppressed after 10 day incubation, which indicated that the average wall-to-wall distances of the CNW scaffolds affect suppression of Runx2 and OC gene expression.
Tomonori Ichikawa, Kenji Ishikawa et al. ACS Applied Bio Materials 2 (7), pp. 2698-2702 (July 15, 2019). link
Effect of electrical stimulation on proliferation and bone-formation by osteoblast-like cells cultured on carbon nanowalls scaffolds
When the cells were incubated on the Carbon nanowalls (CNWs) scaffold, electrical stimulation promoted proliferation but bone formation and the formation of calcified nodules were suppressed in contrast to the case without electrical stimulation (ES). The utility of cell culture methods is demonstrated using CNWs with ES to control osteoblast proliferation and bone formation for use in regenerative medicine
Tomonori Ichikawa, Kenji Ishikawa et al. Applied Physics Express 12 (2), 025006 (pp. 1-4) (February 1, 2019). link
Single-Step, Low-Temperature Formations and In-Situ Binding of Tin Oxide Nanoparticles to Graphene Nanosheets by In-Liquid Plasma for Potential Applications in Gas Sensing and Li-Ion Batteries
Single-step atmospheric-pressure processing was achieved at a low temperature by employing in-liquid plasma in a solution of tin chloride (SnCl2·2H2O) in ethanol as the only precursor. The in situ binding of tin oxide (SnO2) nanoparticles (SNp) and graphene nanosheets (GNs) was successfully synthesized the composite (SNp/GNs) with SNp of sizes 2−3 nm, which were distributed uniformly and attached to both sides of the GNs.
Ranjit R. Borude, Kenji Ishikawa et al. ACS Applied Nano Materials 2, pp. 649-654 (February 22, 2019). link
Facile synthesis of SnO2-graphene composites employing nonthermal plasma and SnO2 nanoparticles-dispersed ethanol
Tin oxide (SnO2)-graphene composite was synthesized by the in-liquid plasma method using SnO2 nanoparticles (average diameter ~30 nm) dispersed ethanol as a carbon precursor. The SnO2 nanoparticles were distributed uniformly on flaky graphene sheets.
Ranjit R. Borude, Kenji Ishikawa et al. Journal of Physics D: Applied Physics 52 (17), 175301 (pp. 1-9) (February 18, 2019). link