内照射核素诱发免疫和遗传效应

机体的免疫系统是生物体防御机制的重要部分,免疫细胞对放射性核素内照射有高度的敏感性。受放射性核素内照射损伤的机体,可诱发免疫器官的功能严重障碍及器质性变化,可抑制免疫细胞的分化与增殖,并诱发不可逆的后遗症,导致中枢免疫器官和外周免疫器官一系列的免疫损伤效应发生。探讨内污染辐射效应对遗传物质损伤带来的后果的研究内容,已从对本代健康影响的观察,进而深入发展到对下一代危害的研究。文中探讨了受放射性核素内照射诱发体细胞和生殖细胞的遗传损伤效应,以及内照射核素诱发放射遗传效应的分子基础DNA损伤与基因突变和染色体畸变的关系。     

辐射免疫学研究的某些进展

本文综述了辐射免疫效应研究中的若干进展,着重点是辐射免疫学与辐射致癌的关系。文中第一部分讨论了淋巴细胞的放射敏感性,强调淋巴细胞群体的异质性,不同淋巴细胞亚群及其亚组的相对放射敏感性,以及激活状态对淋巴细胞放射敏感性的影响。第二部分涉及免疫监视学说的要点,抗肿瘤免疫的特异和非特异成分,以及辐射对它们的影响。第三部分是关于辐射引起的免疫增强现象和辐射刺激作用在免疫系统的表现,并简述了著者实验室有关辐射刺激作用的某些资料。文章强调指出需要对低水平辐射对免疫系统和其它防御适应功能可能引起的刺激作用及其机制进行更细致的研究。     

电离辐射与淋巴细胞

早期的临床工作是了解淋巴细胞的辐射剂量与效应关系,作为初期最敏感的指标之一。对原子弹受害者的淋巴细胞也进行了远期效应的观察。实验室工作方面研究了淋巴细胞的活力、死亡率,玫瑰花结、细胞膜和DNA等分子的变化。染色体畸变,微核率及其相互关系的研讨也引起人们重视。 应用PHA、ConA、PWM、LPS分别激活淋巴细胞的各个亚群,研究其辐射效应。有关PHA激活的T淋巴细胞的辐射效应研究得较多。作者察觉PWM和ConA激活的淋巴细胞对辐射敏感,均减弱了辅助B淋巴细胞转化的作用,PHA激活的淋巴细胞受影响较轻,LPS激活的淋巴细胞变化最小。 单克隆抗体技术研究淋巴细胞亚群的进展为进一步研究淋巴细胞的辐射效应提供条件,可以了解辐射影响免疫功能的主要环节。 有的作者研究了各种病人的淋巴细胞的辐射敏感性,以了解免疫方面存在的缺陷,还可作为制定辐射治疗某些白血病方案的依据。     

13 DNA损伤谱的模拟和分析

随着科学技术的发展，辐射生物效应的研究越来越引起人们的重视。脱氧核糖核酸（deoxvribonucleic acid，DNA）是生物体的遗传物质，也是辐射生物学效应研究的最重要的靶分子，DNA的辐射损伤问题一直是分子放射生物学的中心课题。对DNA原初损伤谱的模拟和计算，是对辐射作用机理解释和预测的第1步，DNA损伤谱的理论模拟已成为本领域的一个强有力的工具。辐照损伤的复杂程度对于细胞的修复、细胞凋亡以及放射治疗等等有很大的影响，因而DNA损伤的研究对于癌症的治疗、辐射环境的健康评估以及辐射防护等等是非常重要和必要的。     

辐射致癌效应与机制

电离辐射是已确定的物理致癌因子.辐射致癌效应的发现要追溯到上世纪初,当时,从事超量放射性物质操作却未做有效防护的职业研究人员中,有不少后来身患癌症,随后大量的动物实验也证实辐射的致癌性.在对日本原爆幸存者、有关矿工等受照人群的癌症发生率和死亡率的流行病学研究的基础上,建立了癌症危险估算模型.辐射致癌的细胞和分子机理的研究,近年来取得了重要进展,包括辐射致DNA集簇性损伤与基因突变的启动事件、基因组不稳定性、细胞增殖调控的信号转导机制、旁效应引申出的辐射非靶效应等.对辐射致癌相关基因的分离鉴定和功能研究,也取得了重要进展.     

浓缩铀诱发免疫细胞凋亡的形态观察及IL-2和IL-6的防护作用

对浓缩铀２３５Ｕ内照射人淋巴细胞白血病细胞株Ｍｏｌｔ４细胞和巨噬细胞株Ａｎａ１细胞诱发的细胞凋亡及细胞因子的防护作用进行了研究。实验中估算了２３５Ｕ在不同阶段培养细胞中的辐射累积吸收剂量。通过荧光显微镜形态观察，发现免疫细胞在受２３５Ｕ辐照后，可诱发明显的以核断裂和核固缩为特征的细胞凋亡。微观放射自显影研究显示，２３５Ｕ可迅速被免疫细胞吞噬，在细胞内以吞噬小泡的形式均匀地弥散于胞浆和胞核内。研究发现，ＩＬ２和ＩＬ６这两个细胞因子对由２３５Ｕ诱发的免疫细胞ＤＮＡ链断裂具有显著的防护作用。研究结果对于临床上寻找提高内照射放射治疗病例的免疫功能措施，具有一定的价值。     

DNA损伤谱的模拟和分析

随着科学技术的发展,辐射生物效应的研究越来越引起人们的重视。脱氧核糖核酸(deoxyribonucleic acid,DNA)是生物体的遗传物质,也是辐射生物学效应研究的最重要的靶分子,DNA的辐射损伤问题一直是分子放射生物学的中心课题。对DNA原初损伤谱的模拟和计算,是对辐射作用机理解释和     

重离子束辐射生物学效应研究热点及其进展

随着生物学技术的发展,重离子束辐射生物学效应的研究在研究手段和研究对象上都经历着由表型到基因型、定性到定量的转变,逐步深入到分子层次。在分子水平上,生命物质对重离子束辐射具有特定的损伤、修复行为,而相应数学物理模型的构建可实现重离子束辐射生物学效应的定量评估,同时,重离子束辐射诱导旁观者效应的研究对于减轻病灶周围健康组织在重离子放疗中的损伤具有重要意义。     

耐辐射球菌PprI蛋白对急性放射损伤小鼠防护作用的初步研究

研究耐辐射球菌PprI蛋白对哺乳动物急性放射损伤的防护作用,初步探讨其作为一种新的抗辐射蛋白的作用机制。将PprI蛋白或生理盐水注射入小鼠肌肉内,观察辐照后第1、7、14、28天小鼠外周血象以及小鼠骨髓、胸腺和脾脏淋巴细胞的凋亡情况。研究结果表明：与生理盐水注射组相比,PprI蛋白注射组外周血白细胞计数于照后第28天显著增高（p〈0．05）;外周血小板数和淋巴细胞百分率于照后第1、7天显著增高（p〈O．05）;PprI蛋白注射组脾脏淋巴细胞凋亡率在照后第1、7、14天明显降低（p〈0．05）;胸腺淋巴细胞凋亡率于照后第14和28天明显降低（p〈0．05）;骨髓细胞凋亡率在照后第1、14和28天明显降低（p〈0．05）;并且骨髓细胞凋亡率于照后第28天基本恢复正常。上述结果初步表明,耐辐射球菌PprI蛋白对哺乳动物急性放射损伤有着明显的防护作用。     

微剂量及微剂量辐射效应

介绍发生在分子水平的原发辐射效应,射线能量在微组织水平的沉积,次级电子微剂量效应在细胞损伤中的作用,以及基因微剂量效应对细胞存活的影响,为定量描述各种微观辐射效应,更加准确认识和理解低剂量辐射诱导的各种生物效应,科学评估低剂量辐射的健康危害,引出微剂量和微剂量事件等术语和概念。     

微束单细胞照射的研究和发展

了解低剂量辐射效应等辐射生物学基本问题的关键是研究单一粒子与生物体的相互作用。然而 ,由于粒子在能量、径迹上的随机分布 ,这种单一粒子与生物体的相互作用很难在实验室中用常规照射的方法进行。微束的发展 ,特别是单粒子微束通过将精确数量的粒子准确地射入细胞或细胞的特定位置为回答这些问题提供了一个直接 ,有用的手段。该文论述了微束的历史 ,现状和未来发展 ,以及微束在辐射生物学研究中的应用。     

On-site production of butt welds for pipes by mechanized equipment

In the field of welding technology significant steps towards automation and mechanization have so far only been made with resistance welding in the automobile industry. By contrast relatively modest progress has been achieved with electric arc welding. One impediment in the field of electric arc welding is the difficulty encountered with fixed positions. Only the development of pulsed inert gas welding, in particular of pulsed TIG welding with cold filler wire addition, made it possible to execute mechanized welding of the most difficult joints in all fixed positions (horizontal 1G or 1F, vertical 3G or 3F, flat overhead 4G or 4F, horizontal 2G) and difficult root passes as well as filler passes. Furthermore the development of transistorized power sources allowed parameters, once established, to be reproduced with great precision. However it was not until computer-controlled programming equipment was matched to the welding systems that the step towards automated, freely programmable arc welding became possible. A number of examples is cited to demonstrate the possibilities that these systems now afford.     

Ultrasonic Imaging Modalities for Medical Applications

The ability to "see" with sound has long been an intriguing concept. Certain animals, such as bats and dolphins can do it readily but the human species is not so endowed by nature. However, this lack of natural ability has been overcome by developing an appropriate technology. For example, in various laboratories recently, workers were able to obtain true-focused orthographic images in real time of objects irradiated with sound rather than with light. Cross-sectional images have been available for a much longer period of time stemming from the development of pulse-echo techniques first used in the sonar systems of World War I. By now a wide variety of system concepts for acoustic imaging exist and have been or are being applied for medical diagnosis. The newer systems range from tomographic types using computers to holographic ones using lasers. These are dealt with briefly here.     

DYN3D-MSR spatial dynamics code for molten salt reactors

The development of spatial dynamics code for molten salt reactors (MSRs) is reported in this paper. The graphite-moderated channel type MSR – one of the ‘Generation IV’ concepts – was selected for the numerical simulation. It has several peculiarities (e.g. the drift of delayed neutrons precursors), which disable the use of standard dynamics codes. Therefore, the own DYN3D-MSR code was developed. It is based on the light water reactor code DYN3D and it allows transients simulation by 3D neutronics and parallel channel thermal-hydraulics. The neutronics and thermal-hydraulics were modified for the MSR peculiarities, where the experience from DYN1D-MSR development was exploited. The code was validated on experimental results from the MSRE experiment done in Oak Ridge National Laboratory and by the comparison with other codes especially with the 1D version. However, by the 3D code transients can be simulated, where space-dependant efforts are relevant, like local blockage of fuel channels or local temperature perturbations.     

Status and prospect of the development of liquid lithium limiters for stellarotor TJ-II

Stellarator concept is considered as a promising approach for power fusion reactor development because it basically free from disruptions and other extreme thermal load events. However, the potential problem of impurity accumulation in stellarator plasma should be taken into account. Very promising results in density control, plasma reproducibility and confinement characteristics have been obtained with application of “lithiation” technology. The next step in the improvement of TJ-II Heliac plasma performance is the development and creation of two poloidal liquid lithium limiters (LL). Experimental possibilities, design, structural materials and main parameters of LL based on capillary-pore structure (CPS) filled with liquid lithium are considered. Understanding in hydrogen isotope interaction with liquid lithium surface is an important aspect of lithium technology development for fusion reactor application. Therefore study of deuterium sorption/desorption process on a lithium surface of LL is stipulated. The development of lithium CPS based devices decreasing intensity of plasma–wall interaction on a central “groove” of TJ-II vacuum camera is proposed as the further step in plasma performance improvement owing to decrease in impurity flux from the wall.     

Nuclear fuel considerations for the 21 century

There are many external influences that may control the path that nuclear power deployment follows. In the next 50 years several events may unfold. Fear of the consequences of the greenhouse effect may produce a carbon tax that would make nuclear power economically superior very quickly. This, in turn, would increase the rate at which uranium reserves diminish due to the increased rate of nuclear power deployment. However, breakthroughs in the extraction of uranium from the sea or deployment of fast breeder reactors would greatly extend the uranium reserves and, as well, utilize the thorium cycle.On the other hand, carbon sequestering technology breakthroughs could keep fossil fuels dominant for the remainder of the century. Nuclear power may only then continue, as today, in a lesser role or even diminish. Fusion power or new developments in solar power could completely displace nuclear power as we know it today.Even more difficult to predict is when the demand for mobile fuel for transportation will develop such that hydrogen and hydrogen rich fuel cells will be in common use. When this happens, nuclear power may be the energy source of choice to produce this fuel from water or methane. In a similar vein, the demand for potable and irrigation water may be another driver for the advent of increased deployment of nuclear power.With all these possibilities of events that could happen it appears impossible to predict with any certainty which path nuclear power deployment may take. However, it is necessary to define a strategy that is flexible enough to insure that when a technology is needed, it is ready to be deployed.For the next few decades there will be an evolutionary improvement in the performance of uranium oxide and mixed uranium oxide-plutonium oxide (MOX) LWR fuels. These improvements will be market driven to keep the cost of fuel and the resulting cost of nuclear power electricity as competitive as possible. The development of fuels for accelerator transmutation and for reactor transmutation with inert matrix fuels is in its infancy. A great deal of research has been initiated in a number of countries, which has been summarized in recent conferences. In Europe the work on these fuels is directed at the same problem as their utilization of MOX; namely to reduce the inventory of separated plutonium, minor actinides, and Long Lived Fission Products (LLFP). In the United States there is no reprocessing and thus no inventory of separated civilian plutonium. However, in the United States there is a resistance to a permanent spent fuel repository and thus accelerator transmutation presents a possible alternative. If nuclear power does have a long-term future, then the introduction of the fast reactor is inevitable. Included in the mission of the fast reactors would be the elimination of the inventory of separated plutonium while generating useful energy. The work that is ongoing now on the development of fuel concepts for assemblies that contain actinides and LLFP would be useful for fast reactor transmutation.There is still a great deal of work required to bring the fast breeder reactor option to maturity. Fortunately there is perhaps a fifty-year period to accomplish this work before fast breeders are necessary. With regard to fast reactor fuel development, future work should be considered in three stages. First, all the information obtained over the past forty years of fast reactor fuel development should be completely documented in a manner that future generations can readily retrieve and utilize the information. Fast reactor development came to such an abrupt halt world-wide that a great deal of information is in danger of being lost because most of the researchers and facilities are rapidly disappearing. Secondly, for all of the existing fast reactor fuels, and this includes, oxides, carbides, nitrides, and metallic fuels, the evolutionary work was far from being completed. Although mixed oxide fuels were probably the furthest advanced, there were many concepts for improved claddings and advanced fabrication methods that were never fully explored. Finally, with such an extended period before fast reactors are needed there is ample time for truly innovative fuels to be developed that are capable of performing over a wide range of conditions and coolants.     

Nuclear energy strategy in the environment of utility business deregulation

Nuclear power has contributed to the reduction and stabilization of electricity rate in Japan. However, its economic competitiveness has been eroding since mid 80's. Deregulation is hitting nuclear power just at the time its competitiveness is declining, and it poses a threat to drive short-sighted market orientation and precludes long term focus on achieving a balance between “environmental agenda” and “competitiveness in market”. Lowering the electricity rate is one of the important agenda to improve the nation's industrial competitiveness in the global market. However, it will be very difficult to win the competition of gas and oil prices with other developed countries in Europe and North America due to a handicap of long transportation distance. Only nuclear power and natural energy have no relation to such a handicap of economic distance from resources. Without securing economic superiority of those energy sources, Japan will not be able to clear the handicap of energy costs. The Japanese utilities are trying hard to regain the competitive edge of nuclear power. We have established short-term strategies for both existing and new LWRs as well as a long-term strategy for technological development. With these strategies we will be able to regain the competitiveness of nuclear power.     

事故应急计划和准备的某些问题的讨论

核能发展的历史证明,核能是一种清洁的、安全的能源。但现代科学技术还不能绝对排除严重事故发生的可能性,因此有必要制定事故应急计划和作好应急准备。事故应急计划的要求应符合正当性的原则,对所采取的防护措施应进行最优化的分析。在制定应急计划时,应充分发挥现有人力和物力的作用;并需十分注意教育、培训和演习。     

Special issue on selected papers from CEPC 2020

The development of electric propulsion has taken decades and in fact,began flight testing as early as the 1960s.However,it was initially slow to develop as an alternative to chemical propulsion systems due to the lack of available on-board electrical power for space vehicles.Since the turn of this century,the booming satellite market,and in particular for small satellites,has driven the demand for propulsion systems with high specific impulse,precisely adjustable thrust,long lifetime,and adaptable for different kinds of small vehicles.At the same time,Hall,ion,arcjet and other forms of electric thruster technologies have reached a mature level,the success of in-orbit testing further stimulated the applications of electric propulsion technology.In recent years,a number of commercial compa-nies have proposed plans for small satellite constellations in low Earth orbit,providing broader opportunities for the development and application of electric propulsion technology.The age of electric propulsion has arrived.     

薄窗型多阳极气体探测器研究进展

薄窗型气体探测器是最近发展并用于低能量加速器质谱探测技术。该探测器的入射窗采用氮化硅膜，薄而均匀，分辨率高，目前已在低能量粒子探测技术中得到初步应用，显示出广泛的应用前景。本文主要从薄窗型气体探测器基本原理、薄氮化硅膜与Mylar膜的对比、不同质子数Z的低能量粒子脉冲高度对比、薄窗型气体探测器与硅探测器的对比，以及应用等方面进行阐述。