•Combined effects of psychological stress and X-rays on wild type mice were analysed.•Either psychological stress or X-rays reduced the number of splenocytes.•Psychological stress alone did not ...induce chromosomal aberrations in splenocytes.•Psychological stress did not appear to synergize with the clastogenicity of X-rays.•Psychological stress may not synergize with radiocarcinogenesis in wild type mice.
Both ionizing radiation (IR) and psychological stress (PS) cause detrimental effects on humans. A recent study showed that chronic restraint-induced PS (CRIPS) diminished the functions of Trp53 and enhanced radiocarcinogenesis in Trp53-heterozygous (Trp53+/−) mice. These findings had a marked impact on the academic field as well as the general public, particularly among residents living in areas radioactively contaminated by nuclear accidents. In an attempt to elucidate the modifying effects of CRIPS on radiation-induced health consequences in Trp53 wild-type (Trp53+/+) animals, investigations involving multidisciplinary analyses were performed. We herein demonstrated that CRIPS induced changes in the frequency of IR-induced chromosomal aberrations (CAs) in splenocytes. Five-week-old male Trp53+/+ C57BL/6J mice were restrained for 6h per day for 28 consecutive days, and total body irradiation (TBI) at a dose of 4Gy was performed on the 8th day. Metaphase chromosome spreads prepared from splenocytes at the end of the 28-day restraint regimen were painted with fluorescence in situ hybridization (FISH) probes for chromosomes 1, 2, and 3. The results obtained showed that CRIPS alone did not induce CAs, while TBI caused significant increases in CAs, mostly translocations. Translocations appeared at a lower frequency in mice exposed to TBI plus CRIPS than in those exposed to TBI alone. No significant differences were observed in the frequencies of the other types of CAs (insertions, dicentrics, and fragments) visualized with FISH between these experimental groups (TBI+CRIPS vs. TBI). These results suggest that CRIPS does not appear to synergize with the clastogenicity of IR.
The formation of stable back beads in the first layer weld during one side multilayer welding is important to achieve high quality welded metal joints. The authors thus employed the switch back ...welding method for welding of V groove joints, from 2mm to 4.5mm root gap, without using backing plates. In this method, a power source, a wire feed unit and robot manipulators are the computer based cooperative control. In this robotic welding system, there are 4 personal computers, which control the welding robot, the digital welding power source and the wire feeder unit. Each unit is connected with Ethernet and UDP, User Datagram Protocol. By using this system, the authors investigate the relationship between the torch weaving and the pulsed welding current. For this purpose, the arc behaviors are taken with a high speed video camera. By analyzing these images, the waveform of the pulsed welding current is determined, i.e., in order to get a good back bead, it is important to discharge the arc to the root edge and the groove surface. The weaving frequency is up to 3Hz so that the switch back welding is applied to V groove backing less welding by using conventional welding robots.In the weaving frequency of 10Hz, 5Hz and 2.5Hz, the relationship between the pulsed welding current and the back bead shape are investigated. The suitability of the welding conditions for each root gap was verified by observation of the arc, molten pool and external appearance of back beads. A good quality of the welding was obtained under 2.5Hz weaving frequency. The feed-forward controller was designed to get a good back bead regardless of the gap variation. In order to verify the validity of the controller, the welding experiments were carried out. A wide and stable back bead was obtained regardless of the gap variation from 4.5 to 2mm.
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