Nuclear microscopy of single whole cultured cells: Beam damage studies

Elemental analysis of individual whole cultured cells using Particle Induced X-ray Emission (PIXE), Scanning Transmission Ion Microscopy (STIM) and Rutherford Backscattering Spectrometry (RBS) can yield quantitative results at the parts per million level. During a continuous scan over a single cell using 2 MeV protons (with a beam current of 100 pA, spot size of 1 μm), elemental loss was monitored and a 60% reduction in hydrogen and oxygen was observed. Concentrations of C, Na, Mg, P, S, Cl, K, Ca, Fe, Cu, and Zn remained constant. The elemental analysis, at the parts per million level, of single whole cultured cells is therefore not limited by beam damage. However, during the irradiation, the size of the cell was observed to shrink by 20%, placing severe restrictions on the imaging and analysis of subcellular structures such as organelles.     

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.     

电离辐射对人肝细胞MXR7基因表达的影响及放射性工作人员外周血MXR7的表达分析

为探讨电离辐射对人正常肝细胞及外周血MXR7基因表达的影响,利用⁶⁰Co γ射线对培养的人肝细胞HL-7702进行照射,同时,抽取某工厂放射性工作人员外周血,通过实时荧光定量PCR对照射后的各剂量组肝细胞及放射性工作人员外周血MXR7基因的表达情况进行检测分析。结果表明,电离辐射可诱导人正常肝细胞MXR7基因的差异表达,且基因表达与照射剂量存在一定的剂量相关性;放射性工作人员外周血MXR7基因表达与非放射性工作人员相比显著升高。     

Nuclear microscope analysis of blood cells from the tropical ascidian Phallusia philippinensis

The present study examines the concentrations of vanadium, bromine and sulphur contained within cryofixed/freeze dried blood cells of the ascidian Phallusia philippinensis (Millar, 1975). Elemental profiles of seven cell types were obtained using the National University of Singapore nuclear microscope. Morula cells were found to contain the following mean values; 0.8% vanadium, 3.5% bromine and 6.1% sulphur. Signet ring cells contained 0.5% vanadium, 2.4% bromine and 1.5% sulphur. Compartment cells had 0.1% vanadium, 2.1% bromine and 2.4% sulphur. Other less abundant cell types such as lymphocytes, macrogranular amoebocytes, carotenoid pigment cells and granular amoebocytes were also analysed and found to contain 0.4%, 0.7%, 0.2% and 1.0% vanadium, 2.0%, 1.6%, 0.6% and 1.2% bromine and 1.3%, 1.5%, 0.3% and 4.3% sulphur respectively. Sulphur occurred in high levels in all cell types, which could indicate its involvement in the vanadium concentration process, while bromine, incorporated into complexes, may be utilised for anti-fouling rather than as a deterrent to predators.     

人肝中元素含量的中子活化分析研究

用仪器中子活化分析方法测定了我国天津市47例正常人（意外死亡）肝脏中Ca、Cd、Co、Cr、Fe、Mo、La、Sm、Zn等16种的含量。用t检验比较了男、女性肝脏中这些元素含量的差别,发现对大多数元素无显著性差异,但Cd、Co、Fe、Mo、La、Zn的含量在男、女性肝脏中存在显著或非常显著性差异。将这些测定值与文献报道的国内外不同地区正常人的值进行了比较,未发现有明显的异常。还用多元统计分析方法研究了正常人肝脏中不同元素间的相关性,并根据不同元素在电子结构、化学性质方面的相似程度及它们在人体中的生理功能等给予一定的解决,它可为探索人体内各种微量元素间的内在联系有意义的信息。     

Recent results in ion beam induced charge microscopy: Unconnected junction contrast and an assessment of single contact IBIC

The recent development of Ion Beam Induced Charge Microscopy (IBIC) promises to deliver a powerful imaging tool for the analysis of active regions in microelectronics devices. The high penetration power (47 μm for 2 MeV protons in Si) allows direct high resolution access to buried structures, a feature not available to the well established EBIC (Electron Beam Induced Current) technique. As multi-level designs become more prevalent this deep penetration is a significant advantage. We report several results: firstly, that contrast is present in IBIC images from junctions that are not directly connected to the preamplifier. The contrast from unconnected junctions vanishes if these junctions are short circuited. Secondly, we discuss the degradation of IBIC images under prolonged irradiation for protons and He⁺ ions. Finally, we discuss the feasibility of single connection IBIC imaging. We demonstrate that IBIC imaging is possible with only one connection to the device substrate.     

Nuclear design and analysis of a magnetic fusion production reactor

Tandem-mirror- and tokamak-based magnetic fusion production reactors are predicted to have tritium breeding ratios of 1.67 and 1.49, respectively. The latter value replaces one (1.56) that is used elsewhere in the sequence of papers in this issue. Blanket energy multiplication for both is predicted to be about 1.3. With the tandem mirror operating in the plutonium production mode, the net plutonium-plus-tritiurn breeding ratio is 1.74. Blanket energy multiplication for the plutonium mode is predicted to be 2.4 at a plutonium-uranium ratio of 0.7% and a uranium volume fraction of 3%.This paper represents work carried out from 1980 to 1982 and was in draft form in 1982. It was received for publication with only minor editing of its 1982 version, explaining the fact that some of the material is dated.     

Imaging of single cells and tissue using MeV ions

With the attainment of sub-100 nm high energy (MeV) ion beams, comes the opportunity to image cells and tissue at nano-dimensions. The advantage of MeV ion imaging is that the ions will penetrate whole cells, or relatively thick tissue sections, without any significant loss of resolution. In this paper, we demonstrate that whole cells (cultured N2A neuroblastoma cells ATCC) and tissue sections (rabbit pancreas tissue) can be imaged at sub-100 nm resolutions using scanning transmission ion microscopy (STIM), and that sub-cellular structural details can be identified. In addition to STIM imaging we have also demonstrated for the first time, that sub-cellular proton induced fluorescence imaging (on cultured N2A neuroblastoma cells ATCC) can also be carried out at resolutions of 200 nm, compared with 300–400 nm resolutions achieved by conventional optical fluorescence imaging. The combination of both techniques offers a potentially powerful tool in the quest for elucidating cell function, particularly when it should be possible in the near future to image down to sub-50 nm.     

Limited angle STIM and PIXE tomography of single cells

STIM (scanning transmission ion microscopy) tomography has been shown to be a valuable method for the three-dimensional characterization of microsamples. It has, however, rarely been employed for the study of single cells, since a free-standing sample is needed for an ordinary tomography experiment. This requirement places high demands on sample preparation techniques.In this study cells fixated on a substrate rather than free-standing were used for tomography. Since the substrate prevented a full rotation of the sample an algorithm for limited-angle tomography was devised. STIM projections covering only a limited angular range of ca. 120° were supplemented with simulated projections generated from a back and forth iteration between real space and Radon space. The energy loss caused by the substrate was subtracted from each projection. The cells were reconstructed using filtered backprojection. The surface of the cells as well as some interior structures could be reconstructed.Following the STIM projections a lesser number of PIXE (particle induced X-ray emission) projections were taken in order to obtain information about the elemental distribution of the sample. From the PIXE projections the three-dimensional phosphorus distribution within the cell was reconstructed using limited-angle tomography. Superimposition of the STIM and PIXE tomograms revealed the location of intracellular structures.Whereas STIM tomography is sensitive to density contrast, which are greatest at the surface, PIXE tomography is sensitive to changes in elemental concentration. Hence, the combination of the two methods can be very fruitful, while the limited angle approach can compensate some of the difficulties associated with tomography of single cells, namely preparation difficulties and excessive sample damage.     

肝癌栓塞治疗剂~(131)I-碘化油的制备和动物实验

以丙酮为溶剂进行同位素交换反应制备~(131)I-碘化油,操作简便,标记率可达95％以上。室温放置15d及高压灭菌后未见脱碘现象。γ照相显示~(131)I-碘化油注入狗的肝动脉后,仅选择性地蓄积于注入动脉的供血区内,甲状腺及肺等其它部位未见核素蓄积。~(131)I-碘化油在肝内的有效半衰期为4.92±0.66d。每毫升血液放射性仅为注入量的0.09±0.04％,提示~(131)I-碘化油性能稳定,适宜临床应用。     

Nuclear microprobe analysis of brain tissue: Quantitative aspects and concentration variability of minor and trace elements

Specimen mass loss, major element loss, and alterations in minor and trace elements during nuclear microprobe bombardment were studied for various types of human brain tissues. The results were quite similar to those of an earlier study on bovine liver (Van Lierde et al., 1995). Special efforts were made to obtain accurate micro-PIXE concentration data (expressed in μg/g dry weight). This involved determination of the local specimen mass thickness. From a comparison of the micro-PIXE data with the results of macro-PIXE it was concluded that micro-PIXE data with an accuracy of better than 20% can be obtained. The variability in elemental concentrations over various types of brain tissue and within a single tissue type were examined. From a scan over the substantia nigra, it appeared that Fe exhibits a complex concentration pattern in this tissue type.     

大亚湾及岭澳两核电站机组同步并网特点及相关故障分析

介绍了大亚湾核电站及岭澳核电站汽轮机控制系统在机组并网、同步及带最小负荷过程中的控制原理,并首次用时序图的形式把控制机理直观地表示出来。针对大亚湾核电站1号机组在并网过程中出现的故障进行了分析说明。     

Nuclear power development in China and uranium demand forecast: Based on analysis of global current situation

There are 438 units of operable nuclear reactors all over the world with a combined capacity of 374,127 MWe today, which generated a total of 2560 TWh in 2009, accounting for 14% of total electricity generation. By contrast, the corresponding indicators in China are merely 11 units, 8587 MWe, 65.7 TWh and 1.9% respectively. Nuclear energy has been regarded as an important component of China’s energy development strategy, and the development of nuclear power industry has been paid high attention by government. In order to speed up the development of nuclear power industry, government has increased the target of installed nuclear power capacity from original 40,000 MWe up to 70,000 MWe by 2020, as well as the under construction capfrom 18,000 MWe up to 30,000 MWe in the same stage. Based on the current development situation and the new national plan on nuclear power, prediction and analysis have been made for uranium supply and demand according to the future national nuclear power development, drawing the conclusion that China’s uranium resources could not satisfy with the demand of nuclear power, and the degree of external dependence would reach as high as 90% or more, indicating that in less than 10 years, nuclear energy, instead of oil, would become the energy with the highest dependence on foreign. In the end of this paper, some suggestion has been proposed for development of nuclear power in China.     

Multi-modality measurement and comprehensive analysis of hepatocellular carcinoma using synchrotron-based microscopy and spectroscopy

The visualization and data mining of tumor multidimensional information may play a major role in the analysis of the growth, metastasis, and microenvironmental ...     

质子激发X射线荧光分析法测定头发、肾和肝中的微量元素

本文使用质子激发X射线荧光分析法(PIXE)测定正常人发、肝和肾组织中的微量元素。详细介绍了样品的采集制备、实验测定和定量方法,并且使用标准参考物质小牛肝(NBS)、马肾(IAEA)和比对粉末发样检查校正测量系统的准确性。报道了三种器官组织中近二十种微量元素的含量,初步探讨了人体自身器官组织中微量元素含量分布之间的相互关系。     

High resolution channeling contrast microscopy and channeling analysis of SiGe quantum well structures

High resolution channeling contrast microscopy (CCM) and channeling measurements were carried out to characterize SiGe quantum well structures on micron thick graded layers (i.e. virtual substrates). The virtual substrates were grown by gas source molecular beam epitaxy at a pressure of 10⁻⁵ mbar and low pressure chemical vapor deposition at 10⁻² mbar on boron doped Si(0 0 1) substrates respectively. A homoepitaxial silicon buffer layer was grown prior to the deposition. The nominal structure is a 20 nm Si_0.75Ge_0.25 layer at the surface, followed by 10 nm pure Si, 500 nm Si_0.75Ge_0.25 and a 1000 nm thick graded SiGe (0–26%) layer. RBS was used to measure the depth profiles, and angular scans around the (1 0 0) axis were carried out to assess crystal and interface quality. CCM was used to acquire depth resolved images of micron-sized lateral inhomogenities (‘cross-hatch') present on both samples.     

Radiochemical analysis of rubble and trees collected from Fukushima Daiichi Nuclear Power Station

To characterize the rubble and trees contaminated by radionuclides released by the recent accident at the Fukushima Daiichi Nuclear Power Station, the radiochemical analysis protocols were modified using those developed by the Japan Atomic Energy Agency for the waste generated by research, industrial, and medical facilities. The radioactivity concentrations of gamma-ray-emitting nuclides ⁶⁰Co, ⁹⁴Nb, ¹⁵²Eu, and ¹⁵⁴Eu, and beta-particle-emitting nuclides ¹⁴C, ¹²⁹I, ³⁶Cl, ⁷⁹Se, and ⁹⁹Tc were successfully applied by the modified analytical method. In contrast, the radioactivity concentrations of ³H, ⁹⁰Sr, ¹³⁷Cs, and alpha-particle-emitting nuclides were applied by the conventional method. Unfortunately, ³⁶Cl, ⁹⁴Nb, ¹²⁹I, ¹⁵²Eu, ¹⁵⁴Eu, and alpha-particle-emitting nuclides were below the detection limit of the conventional method. The measured radioactivity concentrations, except for that of ³H, were not uniform in the area but depended on the reactor unit. Although the radioactivity concentrations were varied widely, this analysis successfully clarified the characteristics of the radioactivity concentrations of the rubble and trees.     

Nuclear analysis and shielding optimisation in support of the ITER In-Vessel Viewing System design

The In-Vessel Viewing System (IVVS) units proposed for ITER are deployed to perform in-vessel examination. During plasma operations, the IVVS is located beyond the vacuum vessel, with shielding blocks envisaged to protect components from neutron damage and reduce shutdown dose rate (SDR) levels. Analyses were conducted to determine the effectiveness of several shielding configurations. The neutron response of the system was assessed using global variance reduction techniques and a surface source, and shutdown dose rate calculations were undertaken using MCR2S.Unshielded, the absorbed dose to piezoelectric motors (PZT) was found to be below stable limits, however activation of the primary closure plate (PCP) was prohibitively high. A scenario with shielding blocks at probe level showed significantly reduced PCP contact dose rate, however still marginally exceeded port cell requirements. The addition of shielding blocks at the bioshield plug demonstrated PCP contact dose rates below project requirements. SDR levels in contact with the isolated IVVS cartridge were found to marginally exceed the hands-on maintenance limit. For engineering feasibility, shielding blocks at bioshield level are to be avoided, however the port cell SDR field requires further consideration. In addition, alternative low-activation steels are being considered for the IVVS cartridge.