A novel coaxial surface dielectric barrier discharge (SDBD) non-thermal atmospheric pressure plasma device, driven by a 35.7-kHz DC pulse and adjustable by a pulse-width modulation, was developed in this study and preliminarily tested for its killing effects of a cancer cell type. This study was divided into three phases, namely, air phase, liquid phase, and cell phase. First, the electrical characteristics and emissions were examined. Two-beam UV-LED absorption spectroscopy was also newly developed to measure the absolute hydroxyl radical (OH⋅) density in the filamentary discharge. Then, the effects of energy doses and treatment durations on three types of liquids and on the colorectal adenocarcinoma cell, SW620, were examined. From Lissajous figures (Q–V plot), the developed SDBD possesses the maximum power density and energy dose of 0.33 ± 0.05 W/cm2 and 19.5 ± 3.00 J/cm2, respectively, when the voltage was set at 3.44 kV and the power at 115 mW. From two-beam UV-LED absorption spectroscopy results, the OH⋅ density increased by 0.32, 0.58, and 0.86 × 1019 m−3, with operational powers of 29, 58, and 115 mW, respectively, within 1-min treatment. In liquid phases, the plasma device can increase the concentrations of H2O2 and NO2− in a time-dependent manner. Finally, cell-phase studies, including the examination of the cell morphology, cell viability, and gene expression of the SW620 cell, show that the device can time-dependently induce the mortality of the SW620 cell, relevant to the up-regulation of the Bax/Bcl-2 expression ratio. Taken together, this novel SDBD plasma device shows potential as another alternative for cancer treatment, although further modification is required.

Abstract. Titanium nitride (TiN) coatings have been used very successfully in a variety of applications because of their excellent properties, such as the high hardness meaning good wear resistance and also used for covering medical implants. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. This paper aims to explain how to optimize deposition conditions for films synthesis on PEEK by varying sputtering parameters such as nitrogen flow rate and direction, deposition time, d-s (target-to-substrate distance) and 13.56 MHz RF power. The plasma conditions used to deposit films were monitored by the optical emission spectroscopy (OES). Titanium nitride/Hydroxyapatite composite films were performed by gas mixture with nitrogen and argon ratio of 1:3 and target-to-substrate distance at 8 cm. The gold colour, as-deposited film was found on PEEK with high hardness and higher surface energy than uncoated PEEK. X-ray diffraction characterization study was carried to study the crystal structural properties of these composites.

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The color of fresh-cut fruits is indicated by the appearance and quality of their products. A sliced apple is a highly putrefying fruit that is sensible to react with oxygen gas, which causes the color, taste, smell, and nutritional value to change during storage in ambient air. Non-thermal atmospheric pressure plasma jet (NTAPPJ) is one of the most crucial applications for food preservation. This study was divided into two parts. First, the emission intensities of the plasma spectrum and electrical properties were investigated. Then, the colorimetric was used to investigate plasma-treated effects on different liquids (tap water, deionized water, and saline water) to delay color changes of fresh-cut apples. The I-V characteristic curve was used to obtain an optimal power of 8.5 kHz-AC pulse-driven NTAPPJ with argon gas. Additionally, the parameter a*, L*, b*, ΔE, h*, YI, Chroma, and browning index (BI) using the colorimeter method were examined. We then demonstrated that using the Ar-NTAPPJ can be considered a novel approach to increasing fresh-cut apple’ toleration and shelf life. Furthermore, plasma exposure is one of the nondestructive processes that does not have any side effects on the products and can significantly delay degradation and discoloration. Keywords: Plasma jet, Shelf life, Colorimeter, Browning index