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This work is devoted to the investigation of the discharge characteristics of an ac arc plasma torch with a well-type cathode working in air and CO2. The electrical characteristics, plasma jet image and optical emission profile are investigated by varying the discharge power and the gas flow rate. The dynamic behaviour of arc voltage and current is characterized by smooth-shaped waveforms, regularly iterated with a driving frequency. The moving of arc spot positions is inferred from the measured waveforms, and compared with that observed in dc torches. A simple lifetime test is performed to verify the speculation that the arc spots in ac operation move continuously over a wide region with a very high speed. The result shows that the electrode lifetime can be enhanced by combining the vortex motion of arc gas with the ac driving. [ABSTRACT FROM AUTHOR]

A novel temporal contrast filter (TCF)-based method was developed to detect supersonic small infrared targets. The proposed hysteresis threshold-based detection followed by the TCF can enhance the accuracy of the target position, the robustness to background clutter and the velocity range of moving targets compared with the conventional temporal variance filter-based method. [ABSTRACT FROM AUTHOR]

Flavonoid has anti-oxidant properties and has been shown to protect cells against oxygen radical damage. This study therefore, evaluated the effect of flavonoid on the in vitrodevelopment ability of porcine embryos produced by parthenogenesis (PA) or somatic cell nuclear transfer (SCNT). Porcine embryos were produced from abattoir-derived prepubertal oocytes either by PA or SCNT of fetal fibroblast into enucleated oocytes essentially as we described earlier (Gupta et al.2008 Mol. Reprod. Dev. 75, 588–597). One-cell embryos were subsequently cultured in NCSU23 + 0.4% polyvinyl alcohol supplemented with or without 10 μmflavanoid for 7 days at 39°C in a humidified atmosphere of 5% CO2in air. Results showed that the presence of flavonoid in the culture medium increased (v. controls) the rate of blastocyst in both PA (31.7 ± 4.0 v. 20.4 ± 2.0%) and SCNT (20.6 ± 2.5 v. 12.2 ± 2.9%) groups, respectively (P< 0.05). These blastocysts also had higher ability to hatch (PA: 53.7 ± 3.6 v. 34.0 ± 2.4%; SCNT: 70.9 ± 2.5 v. 45.7 ± 2.9%) and contained higher cell number (PA: 38.9 ± 2.0 v. 31.3 ± 2.1; SCNT: 37.5 ± 2.0 v. 29.7 ± 2.5) than those of control groups (P< 0.05). Western blot analysis of parthenogenetic blastocysts showed that, flavonoid also reduced the expression of caspase-3 and p38 mitogen-activated protein kinase (MAPK) proteins by 3.1 ± 0.1 and 7.7 ± 0.2 fold, respectively while expression of ERK1/2 protein was increased by 4.7 ± 2.3 fold. The 2′,7′-dichlorofluorescene fluorescence staining of embryos further revealed that the activity of reactive oxygen species (ROS) was significantly reduced in flavonoid treated embryos by 2 fold(P< 0.05). These data therefore, suggest that flavonoid may improve the in vitrodevelopment rate and quality of porcine embryos by reducing ROS activity and change in protein expression. [ABSTRACT FROM AUTHOR]