Single cell elemental analysis using nuclear microscopy

The use of Particle Induced X-ray Emission (PIXE), Rutherford Backscattering Spectrometry (RBS) and Scanning Transmission Ion Microscopy (STIM) to provide quantitative elemental analysis of single cells is an area which has high potential, particularly when the trace elements such as Ca, Fe, Zn and Cu can be monitored. We describe the methodology of sample preparation for two cell types, the procedures of cell imaging using STIM, and the quantitative elemental analysis of single cells using RBS and PIXE. Recent work on single cells at the Nuclear Microscopy Research Centre,National University of Singapore has centred around two research areas: (a) Apoptosis (programmed cell death), which has been recently implicated in a wide range of pathological conditions such as cancer, Parkinson’s disease etc, and (b) Malaria (infection of red blood cells by the malaria parasite). Firstly we present results on the elemental analysis of human Chang liver cells (ATTCC CCL 13) where vanadium ions were used to trigger apoptosis, and demonstrate that nuclear microscopy has the capability of monitoring vanadium loading within individual cells. Secondly we present the results of elemental changes taking place in individual mouse red blood cells which have been infected with the malaria parasite and treated with the anti-malaria drug Qinghaosu (QHS).     

The new nuclear reaction analysis facility at the Lund Nuclear Microprobe

A versatile system for the analysis of the light elements at a Nuclear Microprobe has been constructed. Special reactions for analysis of H (H(p,p)H), Li (⁷Li(p,)), B (¹¹B(p,)2) and F (¹⁹F(p,₁e⁻e⁺)¹⁶O)as well as the general techniques pNRA, PIXE and STIM are employed simultaneously. The set-up is mainly, but not only, intended for thin samples.     

Nuclear microscopy study of fish scales

Fish scales are useful to ichthyologists for purposes of classification, identification, age determination and history study. So far, all studies of fish scales, for whatsoever purposes, have relied on the use of optical or electron microscopes to study their form and structure. Employing the NUS nuclear microscope, we measured the concentrations of Sr, Zn, Fe, Mn, Ni, Cu, Cr, As, Se, Br and Pb in the scales of 17 fish species. The objective was to test the hypotheses that the trace elements in scales could be used for species differentiation, and that the fish scale could potentially be used as a monitor for the environment. Our preliminary results gave positive indications.     

Nuclear microprobe analysis of U-doped (Bi,Pb)2Sr2Ca2Cu3Oy/Ag superconducting tapes

Superconducting (Bi,Pb)₂Sr₂Ca₂Cu₃O_y/Ag tapes are doped with uranium compounds to introduce flux pinning defects from neutron-induced fission. The composition and distribution of elements in cross sections of the tapes were probed with a scanned 3 MeV proton microbeam using proton induced X-ray emission (PIXE). Distributions of the constituent elements were found to be heterogeneous on a scale of 10 μm. By combining the PIXE analysis with Rutherford backscattering spectrometry, the stoichiometry of the superconductor within the tape was measured, including oxygen from elastic scattering, revealing a departure from the desired 2223 composition. In one of the tapes, PIXE elemental maps of the Ag distribution showed diffusion of Ag into the superconductor from the enclosing jacket. Crystals of the same material, not fabricated into tapes, did not contain the contaminants and had a more ideal stoichiometry. Correlation maps between the constituent elements, deduced from the elemental maps, indicate the presence of secondary or unreacted phases.     

Trace elements in sera from patients with renal disease

In hemodialysis (HD) patients, an accumulation of trace elements such as aluminum, copper, silicon and vanadium has been reported. Aluminum-caused encephalopathy and aluminum-related bone diseases are important trace element-related complications. Using particle induced X-ray emission (PIXE) we determined concentrations of aluminum, silicon, copper, zinc, selenium and bromine in sera of 29 patients with HD, 14 nondialysis patients with renal disease (RD) and 27 normal controls. The concentration of serum silicon of the patients with HD was 107.4 ± 61.3 μmol/l, which is markedly higher than that of normal controls (48.3 ± 25.8 μmol/l, p < 0.0001). The serum concentrations of zinc and bromine in patients with HD were 11.9 ± 1.7 and 21.3 ± 3.0 μmol/l, respectively. Both were markedly lower than those of normal controls (15.6 ± 2.6, 69.2 ± 8.3 μmol/l, p < 0.0001). The concentrations of aluminium and bromine in the serum of patients with RD were 171.9 ± 64.3 and 81.9 ± 11.6 μmol/l, which were markedly higher than those of normal controls (p < 0.0001, p < 0.001). No significant differences were observed in the concentration of copper and selenium among three groups.     

Nuclear microscopy of rat colon epithelial cells

Using Nuclear microscopy, we have investigated iron distributions in the colons of Sprague Dawley rats, in order to elucidate heme uptake. Four groups of five Sprague Dawley rats (mean weight 180 g) were fed different purified diets containing either heme diet (2.5% w/w hemoglobin), high fat diet (HFD) (18% w/w fat, 1% w/w cholesterol), ‘western’ diet (combination of hemoglobin 2.5% and 18% fat, 1% cholesterol) or control diet (7% w/w fat). After 4 weeks, animals were sacrificed by exsanguination after anaesthesia.Thin sections of frozen colon tissue were taken, freeze dried and scanned using nuclear microscopy utilising the techniques PIXE, RBS and STIM. The new data acquisition system (IonDaq) developed in CIBA was used to obtain high resolution images and line scans were used to map the iron distributions across the colon boundaries.The nuclear microscope results indicate that when HFD is given in addition to heme, the iron content of the epithelial cells that line the colon decreases, and the zinc in the smooth muscle wall increases. This implies that the level of heme and fat in diet has an important role in colon health, possibly by influencing epithelial cells directly or changing luminal composition such as bacterial flora or levels of metabolites and cytotoxins.     

Nuclear microscopy study of neurofibrillary tangles in Alzheimer''s disease

The NUS nuclear microscope has been utilized to determine aluminium concentrations in normal and neurofibrillary-tangle-bearing neurons in brain tissue sections from Alzheimer's patients. It was demonstrated that both neurons and neurofibrillary tangles can be identified by STIM in situ in thin tissue. High aluminium levels of up to 500 parts per million were found in tissue fixed with osmium tetroxide, with higher concentrations present in neurons than in surrounding tissue. Preliminary results on untreated freeze dried sections however have yielded an absence of aluminium down to the minimum detection limits of 20 ppm, implying that aluminium is an artifact introduced during sample preparation.     

核动力潜艇核应急救援中的若干问题研究

介绍了核动力潜艇的事故类别，分析了潜艇核事故应急响应的特点，对海上核救援中的一些特殊问题——应急状态与应急计划区划分、专业技术救援力量的构成及任务、港区烟羽内外复合照射的防护、海上核救援装备与技术保障能力建设、与失事核潜艇处置的相关问题等作了讨论。     

秦山核电厂核测系统的调试

本文介绍了秦山核电厂核测系统在装料前后、零功率和功率试验阶段的调试过程、方法和主要数据以及源量程、中间量程和功率量程之间的复盖情况。最后对将来核测系统的设计提出了几点建议。     

Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering

Recent activities in the field of Nuclear Operational Management and Nuclear Safety Engineering, the studies related to risk analysis methodology, design, and operational management, physical phenomena, and emergency preparedness and nuclear security, have been progressed. Especially, ‘risk analysis methodology’ and ‘design and operational management’ are the main categories of the field, in which more than half of published articles on Journal of Nuclear Science and Technology are related to these categories.     

发展中的核电子学

本文简要介绍了核电子学的现状和广泛应用的情况。阐述了核电子学的学科特点及其存在和持续发展的原因。     

核电子学与核探测技术领域中的计算机应用问题

文中对近十年来核电子学与核探测技术领域内计算机应用的状况作了概括;简要的讨论了能谱数据获取、计算机断层成象、以及大型数据获取等系统方面的技术进展。对值得注意引用的计算机学科内发展起来的一些新技术与新技术产品作了简单的评价。     

世界核电史三次严重事故的反思

1979年美国三哩岛核事故、1986年前苏联切尔诺贝利核事故和2011年日本福岛核事故是世界核电发展史上三次严重核事故。前事不忘,后事之师。从核事故中总结吸取经验和教训,有利于进一步加强核安全,更好地发展和利用核能为民造福。     

核医学仪器中的微计算机

本文简要评价了Z80 CPU在智能核医学仪器发展中的地位和作用,介绍了智能核医学仪器中内含的Z80微计算机设计中的几个问题。     

核设施机械去污技术及应用

总结了现有的机械去污染及其技术特点,简要介绍了核设施机械去污染技术发展方向的一些去污实践,针对我国去污工作的现状,提出了点建议。     

秦山核电厂核空气净化系统试验与运行

本文介绍了秦山核电厂核空气净化系统的设置,系统功能及运行方式,净化部件的性能参数。文章着重叙述安装工作完成后所进行的现场试验的项目、目的、方法和评价标准。已完成的现场试验证实,秦山核电站核空气净化系统将是可靠高效率的,文章最后介绍了运行管理的要点,指出强化运行管理是核空气净化系统能否发挥预定功能的关键。目前,秦山核电站正向满功率进军,核空气净化系统运行正常,满足了秦山核电厂安全运行的要求。     

我国核电设备国产化的研究

本文根据我国核电站设备设计和制造的经验与实际能力,分析了600MW 核电站设备国产化的必要性和可能性。笔者指出:抓好核岛设备的设计,是国产化的关键;在核电设备制造方面,我国已有一定的基础,只要稍加措施,增添少量关键加工设备和测试仪器,估计可以适应当前的要求。笔者还提出了对现阶段核电设备国产化的步骤和措施。最后,具体分析了我国首套600MW 核电机组的设备制造情况,综合测算其国产化率为70%左右。     

核设备制造中的不符合项控制

不符合项控制对顺利完成核设备制造至关重要。本文以东方锅炉(集团)股份有限公司在广东岭澳核电站2×1000MW电功率压水堆核岛主设备分包制造中的不符合项控制实践为例,阐述了核设备制造中不符合项的控制原则和处理程序等,供从事我国核设备制造行业质量保证工作的有关人员参考。