Because of its high prevalence worldwide, osteoporosis is considered a serious public health concern. Many known risk factors for developing osteoporosis have been identified and are crucial if planning health care needs. Recently, an association between uric acid (UA) and bone fractures had been explored. Extracellular UA exhibits antioxidant properties by effectively scavenging free radicals in human plasma, but this benefit might be disturbed by the hydrophobic lipid layer of the cell membrane. In contrast, intracellular free oxygen radicals are produced during UA degradation, and superoxide is further enhanced by interacting with NADPH oxidase. This intracellular oxidative stress, together with inflammatory cytokines induced by UA, stimulates osteoclast bone resorption and inhibits osteoblast bone formation. UA also inhibits vitamin D production and thereby results in hyper-parathyroidism, which causes less UA excretion in the intestines and renal proximal tubules by inhibiting the urate transporter ATP-binding cassette subfamily G member 2 (ABCG2). At normal or high levels, UA is associated with a reduction in bone mineral density and protects against bone fracture. However, in hyperuricemia or gout arthritis, UA increases bone fracture risk because oxidative stress and inflammatory cytokines can increase bone resorption and decrease bone formation. Vitamin D deficiency, and consequent secondary hyperparathyroidism, can further increase bone resorption and aggravated bone loss in UA-induced osteoporosis.

This work investigates the statistical behavior including the dimensions and electrical properties of a single microdischarge (MD) generated in a planar atmospheric-pressure air dielectric barrier discharge reactor using a kHz sinusoidal power source with a gap of 1.4 mm. The MD diameters and surface wave (SW) dimensions are captured by an intensified charge-coupled device camera with currents and charge transferred being recorded. The average currents measured in positive and negative half periods (HPs) are 58.9 and 50.5 mA, respectively. The average diameters measured are 256 and 258 μm in positive and negative HPs, respectively. Therefore, the average current densities calculated in positive and negative HPs are 1.14 × 106 and 9.66 × 105 A m−2, respectively. The high current density leads to the high density of surface charge reaching up to 51.5 nC cm−2 in the positive HP at the anode, which is one order of magnitude higher than those observed in filamentary discharges using He/N2 mixtures. The gap dimension is adjusted to 2.0 mm to investigate the effect of the gap dimension on MD properties. Larger MD diameters, currents, SW dimensions, and the charge transferred are measured in the gap of 2.0 mm although the average current densities evaluated in positive and negative HPs are lower than those of gap 1.4 mm as 9.39 × 105 and 8.15 × 105 A m−2, respectively. The average density of surface charge evaluated in the positive HP at the anode of gap 2.0 mm is 51.7 nC cm−2, which is almost identical to that evaluated in the gap of 1.4 mm.

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In this work, a semi-empirical 1.5D plasma fluid model (PFM) is proposed to model a single microdischarge (MD) in atmospheric pressure air dielectric barrier discharges (APADBDs). The species continuity equations and the electron energy density equation are solved in onedimensional domain, while the Poisson equation is solved in the axisymmetric domain to capture the enhancement of the electric field in front of the streamer. The framework of air chemistry is considered and the effect of photoionization is modeled in the axisymmetric domain. The accumulation factor (AF) is introduced and determined by experimental data to model the accumulation of charged particles on the dielectric surface. The simulated results in two gaps are compared with experimental measurements. In the gap of 1.4 mm, the simulated electric current reaches 72 mA, which is close to the typically measured electric current. The simulated maximum wave velocity is around 1.7×10 6 m s −1 , which is close to the available experimental data. The change of simulated charge density implies that the average accumulation of charged particles on the dielectric surface during each half period (HP) is around 40 nC cm −2 , which is in the same order of magnitude as the average charge density evaluated in the previous measurements as 51.5 nC cm −2 . The effect of AF is studied and shows that the AF determines both peak and duration of the electric current. In the gap of 2.0 mm, the simulated current reaches 113 mA, which is close to the typically measured current. Although the gap voltage of the 2.0 mm gap is higher than that of the 1.4 mm gap, the average electric field of the 2.0 mm gap is lower than that of the 1.4 mm gap before breakdown due to larger gap distance. The maximum wave velocity is faster than that simulated in the gap of 1.4 mm due to the longer gap distance for developing higher wave velocity as 2.4×10 6 m s −1 . During each HP, the average accumulation of charge density on the dielectric surface reaches around 40 nC cm −2 which is almost identical to that simulated in the gap of 1.4 mm as observed experimentally. In general, the proposed semi-empirical 1.5D PFM captures the dynamics of a single MD in APADBDs.

This work investigates O3 production in a planar atmospheric pressure air dielectric barrier discharge reactor numerically and experimentally. The surface temperature of the reactor is measured by an infrared (IR) thermal imager, and the O3 densities of cases in the reactive zone are measured by ultraviolet absorption spectroscopy. The 1.5D plasma fluid model (PFM) with transverse convection is employed to capture the average properties of a single microdischarge (MD) generated in the reactor and is integrated with the 3D gas flow model for modeling species densities in the reactor. The simulated temperature distribution of the reactor surface is validated by that measured and the simulated O3 densities agree with those measured at different locations and flow rates. In the 1.5D PFM, the simulated results show that the O3 molecules produced in the case of 4 SLM are much more than those produced in the case of 1 SLM though the O atoms produced in the case of 1 SLM are around 20 % more than those produced in the case of 4 SLM. In the case of 1 SLM, more than 48% of O3 molecular generated are destructed, while only around 14% of O3 molecules are destructed in the case of 4 SLM. The analysis shows that around 73% of O atoms generated in the 1.5D PFM are consumed in the formation of O3 molecules in the case of 4 SLM, while only 18% of O atoms generated in the case of 1 SLM are consumed in the formation of O3 molecules. The overall O3 yield efficiency reaches 97 g/kWh with the O3 concentration increasing to 2700 ppm in the case of 4 SLM, while the O3 yield efficiency decreases to 10 g/kWh and O3 concentration drops to 1400 ppm in the case of 1 SLM.