空中设备太阳辐射试验方法研究

高空驻留设备面临严酷的低温、低气压和强太阳辐射综合环境,但现有环境试验方法均采用接近海平面的太阳辐射光谱和强度,在地面温度和压力条件下开展试验,对空中综合环境效应欠考核。分析了空中太阳辐射环境的环境效应,提出了空中低温、低气压和强太阳辐射环境应力条件的确定方法与试验程序,为设备耐高空太阳辐射能力的设计验证和试验考核提供了新方法和新思路。

Comet assay and cytokinesis-blocked micronucleus test for monitoring the genotoxic effects of X-ray radiation in humans

Obejctive To assess the genotoxic effects of X ray radiation on human populations Methods The single cell gel electrophoresis (SCGE) and cytokinesis blocked micronucleus (CBMN) test were applied as biological dosimeters to detect DNA damage and abnormalities in human peripheral lymphocytes of subpopulation exposed to X ray radiation The subjects were divided into four groups: 12 radiation patients; 13 intervention radiation therapy doctors; 32 radiation diagnostians; 28 controls Results The average comet lengths of the four groups were 128 17±4 49?μm, 88 09±5 39?μm, 72 68±2 57?μm and 32 87±0 57?μm, respectively The difference in average comet length between any two groups was highly significant ( P <0 01) The average micronucleated cell (MNC) rates (‰) of the four groups were 12 33±0 85, 9 75±1 02, 8 48±0 66 and 3 18±0 36, respectively The difference of MNC rates of Group 1 vs 3, 1 vs 4, 2 vs 4 and 3 vs 4 was highly significant ( P <0 01), and the difference of Group 1 vs 2 was significant ( P <0 05), but there was no difference of MNC rate in Group 2 vs 3 ( P >0 05) Conclusions This study showed that both the comet assay and the CBMN test could be used to monitor populations exposed to X ray radiation, but the comet assay seems to be more sensitive than the CBMN test

Synchrotron Radiation X-Ray Inducing a Significant Increase in the CD38 Level of Rodent Testes by Generating Oxidative Stress

Synchrotron radiation(SR) X-ray has significant potential for medical applications. However, the mechanisms underlying the effects of SR X-ray on biological tissues remain unclear. Because increasing evidence has indicated critical roles of cluster of differentiation 38(CD38) in various cellular functions and cell survival, in this study we used rodent testes as a model to determine the effects of SR X-ray irradiation on the CD38 level of the testes. We found that SR X-ray irradiation led to a significant increase in the CD38 level of rodent testes one day after the irradiation. In contrast, the SR X-ray irradiation did not produce a significant increase in the CD38 level of the testes from the rats that were administered with the antioxidant N-acetyl cysteine, thus suggesting that oxidative stress plays a significant role in the SR X-ray irradiation-induced increase in the CD38 levels. Our study has also provided evidence suggesting that poly(ADP-ribose) polymerase(PARP) activity is not involved in the SR X-ray irradiation-produced effect on the CD38 levels. Collectively, this study has provided first in vivo evidence indicating that CD38 levels can be increased by ionizing radiation, in which oxidative stress plays an important role. Because oxidative stress occurs in ionizing radiation as well as such diseases as cerebral ischemia and Parkinson's disease, oxidative stress may produce pathological effects by inducing increased CD38 levels.

In situ observation of grain evolution in ceramic sintering by SR-CT technique

Grain evolution of boron carbide ceramic powder during isothermal sintering process was in situ investigated by synchrotron radiation X-ray computed tomography (SR-CT) technique. The process of grain growth and material migration during three sintering stages was clearly distinguished from the 2-D and 3-D reconstructed images. The results show that from room temperature to 1 200 ℃ (0-270 min), grains gradually approach each other and form the sintering neck but grain growth does not start, which is indicated as the initial sintering stage. While the sintering time is between 270-390 min (temperature is 1 200 ℃), material migration between grains starts, while grains and sintering neck grow up, which is defined as the middle sintering stage. As the sintering time exceeds 390 min (temperature is 1 200 ℃), pores become isolated and spheroidized, which shows the final sintering stage. The double logarithm curve of mean grain radius and time logarithm during middle stage of isothermal sintering process is obtained from reconstructed images and the grain growth exponent is 0.364 03, falling in the predicted range of the traditional sintering theory. The experiment results are in accordance with those of the traditional sintering theory and provide effective experimental data for further analysis of the sintering process and the mechanical characteristics of ceramics.

JJG1078医用数字摄影(CR、DR)系统X射线辐射源检定规程分辨力检定分析

在开展疾病的诊断的过程中,所要应用到的非常重要的设备就是数字摄影系统,要想其能够在实际的诊断工作中对患者的疾病作出准确的诊断,保证其计量参数的准确可靠性是非常必要的,这就涉及到医用数字摄影系统检定的问题,本文就主要对JJG1078医用数字摄影(CR、DR)系统X射线辐射源检定规程中有关分辨力检定的问题予以简单分析。