Experimental study of the underwater plasma based on the phased array vibrator system
In this paper, a set of underwater plasma vibroseis system was developed, which included three big systems, i.e. charge system, discharge system and trigger system. At the same time, an experimental platform was set up through tketornix digital oscilloscope, seismic detector and desktop computer for collecting and processing data. On this basis, three working stages (breakdown, detonation and spread) of the underwater plasma were carried out the experimental research and summary. By experiment, the electrical properties of the underwater plasma were investigated under the different electrode materials, different number of electrodes, different voltages, different electrode gap spacing conditions. By using the ORIGIN data analysis software, the plasma channel resistance and the trend of the change of discharge power in time domain were obtained. It laid a foundation for choosing the optimal transducer structure and its material. In addition, the process of pulsed discharge in water was analysed. By comparing and summarizing, it found that the efficiency of corona discharge significantly is higher than that of arc discharge. This research provides references for the design of the plasma source in water.
Transient regime of pulsed breakdown in low-conductive water solutions
The transient regime of pulsed electrical breakdown in both distilled and low-conductive water (σ<15 µS cm-1) has been investigated in a point-to-plane electrode system using quasi-rectangular voltage pulses with a repetition frequency of 25 Hz. Two individual current pulses were observed within the interval of voltages of 18.5-20 kV. The appearance of the transient regime was limited by the minimal capacitance of the storage capacitor C4 nF. While the time lag of the first current was not apparently affected by the capacitance of the storage capacitor, a growth in time lag of the second current pulse was observed as the capacitance was increased. The distortion of the electric field at the head and an increase of the leader channel resistance due to accumulation of the electrostatic charge on the inside wall of the gaseous channel are two most likely mechanisms effective in the transient regime. The enhancement of OH radical production in such a regime can be surmised from spectroscopic observations.
The bradykinin B1 receptor and the central regulation of blood pressure in spontaneously hypertensive rats
We evaluated if the brain bradykinin (BK) B1 receptor is involved in the regulation of blood pressure (BP) in conscious rats. Basal mean BP and HR were 115±2 and 165±3 mmHg and 345±10 and 410±14 beats min−1 in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR), respectively. Intracerebroventricular (i.c.v.) injection of 1 nmol B1 receptor agonist Lys‐desArg9‐BK significantly increased the BP of WKY and SHR by 7±1 and 19±2 mmHg, respectively. One nmol Sar[D‐Phe8]‐desArg9‐BK, a kininase‐resistant B1 agonist, increased the BP of WKY and SHR by 19±2 and 17±2 mmHg, respectively and reduced HR in both strains. I.c.v. injection of 0.01 nmol B1 antagonists, LysLeu8‐desArg9‐BK or AcLys[D‐βNal7,Ile8]‐desArg9‐BK (R715), significantly decreased mean BP in SHR (by 9±2 mmHg the former and 14±3 mmHg the latter compound), but not in WKY. In SHR, the BP response to R715 was associated to tachycardia. I.c.v. Captopril, a kininase inhibitor, increased the BP of SHR, this response being partially prevented by i.c.v. R715 and reversed into a vasodepressor effect by R715 in combination with the B2 antagonist Icatibant. I.c.v. antisense oligodeoxynucleotides (ODNs) targeted to the B1 receptor mRNA decreased BP in SHR, but not in WKY. HR was not altered in either strain. Distribution of fluorescein‐conjugated ODNs was detected in brain areas surrounding cerebral ventricles. Our results indicate that the brain B1 receptor participates in the regulation of BP. Activation of the B1 receptor by kinin metabolites could participate in the pathogenesis of hypertension in SHR.