Hideya Nishiyama

A nonequilibrium argon plasma jet with oxygen addition, generated in a planar dielectric duct and issuing into ambient air with one edge stuck on a dielectric plane, is reported for the first time. This argon-oxygen plasma jet can be operated at low applied voltage as a filamentary discharge at atmospheric pressure. The addition of a small amount of oxygen results in the increase of produced ozone concentration and continuous emissions of centering at about 185 nm, 205 nm, 230 nm, and 253 nm. The synergistic generation of short wavelength ultraviolet emissions and active species is significantly important for plasma applications.

Radical hysterectomy (RH) is a standard treatment for locally advanced non-squamous cell carcinoma (N-SCC) of the uterine cervix, but there have been no reports on whether neoadjuvant chemotherapy (NAC) followed by radical hysterectomy could improve the outcome of patients with this disease. This multicenter retrospective study enrolled 77 patients with Stage IB2 to IIB N-SCC of the uterine cervix. Of these, 27 patients were treated with NAC prior to radical hysterectomy (NAC group) and 50 with RH alone (RH group). The two-year recurrence-free survival (RFS) rate, progression-free survival (PFS), and overall survival (OS) were compared between the two groups. Clinical parameters such as clinical stage, histological type, and postoperative treatment were also examined between the groups. While the two-year RFS rates were 81.5% and 70.0% in NAC and RH groups, respectively (p = 0.27) and the median PFS was 51 months and 35 months in NAC and RH groups, respectively (p = 0.35), the median OS was 58 months and 48 months in NAC and RH groups, respectively, which was significant (p = 0.0014). The median OS of patients with mucinous adenocarcinoma in NAC group was significantly higher than that in RH group: 58 months versus 37 months (p = 0.03). NAC prior to RH may offer the prognostic advantage of patients with locally advanced N-SCC of the uterine cervix, especially mucinous adenocarcinoma.

A real-time computational simulation on the entire cold spray process is carried out by the integrated model of compressible flow field, splat formation model, and coating formation model, in order to provide the fundamental data for the advanced high performance cold gas dynamic spray process with electrostatic acceleration. In this computation, viscous drag force, flow acceleration added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis, and electrostatic force are all considered in the particle equation of motion for the more realistic prediction of in-flight nano∕microparticle characteristics with electrostatic force and also for the detailed analysis of particle-shock-wave-substrate interaction. Computational results show that electrostatic acceleration can broaden the smallest size of applicable particle diameter for successful adhesion; as a result, wider coating can be realized. The utilization of electrostatic acceleration enhances the performance of cold dynamic spray process even under the presence of unavoidable shock wave.

A thermal plasma flow is regarded as a multifunctional fluid with high energy density, high chemical reactivity, variable properties, and controllability by electromagnetic fields. Especially a radio frequency inductively coupled plasma (RF-ICP) flow has a large plasma volume, long chemical reaction time, and a high quenching rate. Besides, it is inherently clean because it is produced without internal electrodes. An RF-ICP flow is, therefore, considered to be very useful for nanoparticle synthesis. However, nanoparticle synthesis using an RF-ICP flow includes complicated phenomena with field interactions. In the present study, numerical analysis was conducted to investigate the synthesis of metallic nanoparticles using an advanced RF-ICP reactor. An advanced RF-ICP flow is generated by adding direct current (DC) discharge to a conventional RF-ICP flow in order to overcome the disadvantages of a conventional one. The objectives of the present work are to clarify the formation mechanism of metallic nanoparticles in advanced RF-ICP flow systems and to detect effective factors on required synthesis. A two-dimensional model as well as a one-dimensional model was introduced for nanoparticle growth to investigate effects of spatial distributions of thermofluid fields in RF-ICP flows on synthesized nanoparticles. In an advanced RF-ICP flow, a characteristic recirculation zone disappears due to a DC plasma jet. Larger numbers of nanoparticles with smaller size are produced by using an advanced RF-ICP flow. Thermofluid fields in RF-ICP flows can be controlled by applied coil frequency by means of skin effect. Larger numbers of nanoparticles with smaller size are produced near the central axis. Dispersion of particle size distributions can be suppressed by higher applied coil frequency through control of RF-ICP flows. Applied coil frequency can be a remarkably effective factor to control nanoparticle size distribution.