Real-Time Reconstruction of Arbitrary Slices for Quantitative and In Situ 3D Characterization of Nanoparticles

A detailed 3D investigation of nanoparticles at a local scale is of great importance to connect their structure and composition to their properties. Electron tomography has therefore become an important tool for the 3D characterization of nanomaterials. 3D investigations typically comprise multiple steps, including acquisition, reconstruction, and analysis/quantification. Usually, the latter two steps are performed offline, at a dedicated workstation. This sequential workflow prevents on-the-fly control of experimental parameters to improve the quality of the 3D reconstruction, to select a relevant nanoparticle for further characterization, or to steer an in situ tomography experiment. Here, an efficient approach to overcome these limitations is presented, based on the real-time reconstruction of arbitrary 2D reconstructed slices through a 3D object. Implementation of this method may lead to generalized implementation of electron tomography for routine nanoparticle characterization in 3D.     

Ultra-high resolution 3D NMR spectra from limited-size data sets

The advantage of the filter diagonalization method (FDM) for analysis of triple-resonance NMR experiments is demonstrated by application to a 3D constant time (CT) HNCO experiment. With a 15N-,13C-labeled human ubiquitin sample (1.0 mM), high spectral resolution was obtained at 500 MHz in 25 min with only 6-8 increments in each of the CT dimensions. This data set size is about a factor of 50-100 smaller than typically required, yet FDM analysis results in a fully resolved spectrum with a sharp peak for each HNCO resonance. Unlike Fourier transform (FT) processing, in which spectral resolution in each dimension is inversely proportional to the acquisition time in this dimension, FDM is a true multi-dimensional method; the resolution in all dimensions is determined by the total information content of the entire signal. As the CT dimensions of the 3D HNCO signal have approximate time-reversal symmetry, they can each be doubled by combining the usual four hyper-complex data sets. This apparent quadrupling of the data is important to the success of the method. Thus, whenever raw sensitivity is not limiting, well-resolved n-dimensional spectra can now be obtained in a small fraction of the usual time. Alternatively, to maximize sensitivity, evolution periods of faster relaxing nuclei may be radically shortened, the total required resolution being obtained through chemical shift encoding of other, more slowly relaxing, spins. Improvements similar to those illustrated with a 3D HNCO spectrum are expected for other triple-resonance spectra, where CT evolution in the indirect dimensions is implemented.     

Performance evaluation of a new reading technique of LR115 cellulose nitrate track detectors

LR115 cellulose nitrate SSNTD are routinely used for Radon detection. A reading technique with high resolution optical microscope coupled with a scanning system has been recently proposed.In this technique, the efficiency correction that was formerly performed on the residual thickness of the detector is performed on the track area distribution. So all the information that is needed for the measurement is obtained directly during the scanning. This leads to a much simpler and faster reading procedure, when compared to the classical technique that required both spark counting and micrometer residual thickness measure.A complete characterization and performance evaluation of the detector response is discussed, including a measuring range evaluation, a combined uncertainty theoretical calculation and a blind test validation at HPA.     

Direct Synthesis of ZIF-8 on Transmission Electron Microscopy Grids Allows Structure Analysis and 3D Reconstruction

The first example of layer-by-layer growth of a metal–organic framework (MOF) directly on transmission electron microscopy (TEM) grids is described. ZIF-8 is deposited on thin amorphous carbon films and subjected to a structure analysis by (scanning) TEM ((S)TEM). This method serves as a two-in-one synthesis and TEM sample-preparation technique and allows straightforward analysis of ZIF-8 crystallites. Artifacts resulting from sample preparation are completely avoided by this approach. The morphological properties, crystal structure, and the chemical composition of the material are investigated with high spatial resolution by a variety of methods of (analytical) electron microscopy. Furthermore, the incorporation of metallic nanoparticles in ZIF-8 by integrating a corresponding step into the layer-by-layer deposition process is examined. The formation of ZIF-8 crystals on the film proceeds as under the absence of nanoparticle-forming synthesis steps. However, the nanoparticles rather cover the supporting amorphous carbon film than being incorporated in the ZIF-8 material. This information cannot be obtained from standard characterization techniques but requires the application of analytical (S)TEM techniques.     

X射线衍射增强成像中吸收、折射以及散射衬度的计算层析

X射线相位衬度成像是一种新型的X射线成像技术,通过记录射线穿过物体后相位的改变对物体进行成像,可以提供比传统的X射线吸收成像更高的图像衬度以及空间分辨力。衍射增强成像方法(Diffraction enhancedimaging,DEI)是X射线相位衬度成像方法之一,利用一块放置在物体和探测器之间的分析晶体提取物体的吸收、折射以及散射信息并进行成像。将衍射增强成像方法与计算机断层成像技术(Computerized Tomography)进行结合,利用吸收、散射以及折射信息,分别采用滤波反投影以及雷登(Radon)变换,对昆虫样品——蜜蜂进行计算层析重建,获得了好于X射线吸收计算层析的重建结果,验证了衍射增强成像信息分离计算层析的优越性。     

基于同步辐射显微CT的肾结石微观结构特征研究

肾结石是全球的泌尿系统常见病、多发病,且复发率高居不下。一般认为,尿中结石晶体的盐类呈超饱和状态,以及尿中抑制晶体形成物质不足是肾结石产生的主要因素。肾结石病因较复杂,目前提出了多种有关肾结石病因的学说,主要是从人体种族遗传、疾病、代谢和饮食习惯等方面研究结石病因,来推测其导致不同的种类的产生,再针对性制定治疗方案,但临床上肾结石内科治疗效果仍欠佳。积极探索肾结石形成和生长机制,无疑能对科学治疗肾结石有积极的意义。直观观察到结石的内部结构,并根据这些结构特征推测出结石的形成和成长轨迹,是研究肾结石形成和生长机制的重要一环。传统的研究手段难以无损获得结石的内部结构,目前未见肾结石微观结构相关报道。高分辨率显微CT特别是同步辐射X射线显微CT的出现,无疑能为这一研究提供先进的检测手段。上海同步辐射光源作为第三代优质同步辐射光源,具有高光子通量、高准直性、高极化性、高相干性及宽频谱范围等特点,其配合高分辨的X射线探测器可实现精确、灵敏的组织结构信息的快速、无损检测,在保持标本完整性的前提下,清晰再现样品内部的三维显微结构,从而克服了传统的二维切片技术存在破坏组织结构的完整性、无法准确获得组织结构的三维空间信息和基质成份等局限性。利用上海同步辐射光源Ｘ射线显微CT技术,对32例肾结石患者的结石微观结构进行了解析。实验结果表明肾结石内部结构差异明显,可归纳为6种类型：Ⅰ两相密实型;Ⅱ结晶型;Ⅲ连续多层沉积型; Ⅳ非连续多层沉积型;Ⅴ镶嵌式多孔型;Ⅵ复合型。研究结果有助于进一步深入揭示肾结石生长机制,也为肾结石更为精准治疗提供了新的科学视角和依据。     

Elemental distribution by synchrotron X-ray microfluorescence of prostate 3D cell culture

Prostate cancer is a highly prevalent disease and ranks second among malignant neoplasms that affect men around the world, behind lung cancer alone. Trace elements are very important and are involved in many cellular processes. The X-ray microfluorescence technique is an advanced tool of high spatial resolution, sensitivity, multielemental analysis, and nondestructiveness for trace element study. This study aimed to investigate the elemental distribution in spheroids obtained through the following human prostate cell lines using synchrotron X-ray microfluorescence: tumor cell line androgen independent (DU145), tumor cell line androgen dependent (LNCaP), and normal cell line (RWPE-1). The measurements were performed with a standard geometry of 45° of incidence, excited by a white beam using a pixel of 25 μm and an acquisition time of 300 ms/pixel at the X-ray fluorescence beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). The synchrotron X-ray microfluorescence results showed differences between groups in all elements analyzed and suggested that further studies should be performed to understand the relationship of these trace elements with the progression and development of the disease.     

近场光学用于激光解吸飞行时间质谱的亚微米级空间分辨成像

基于激光离子源的飞行时间质谱法作为一门新兴的成像方法,已经被广泛应用于材料、地质、环境、药物和生命科学领域中。但受限于光学衍射极限、聚焦透镜的焦距和数值孔径等因素,使其难以实现亚微米尺寸的高空间分辨率成像。近场技术的引入成功地解决了光学衍射极限的限制,将近场技术与激光电离技术相结合,可以实现对固体样品表面纳米级弹坑的剥蚀。此外,传统的质谱成像技术常常假设样品表面是平整的,忽略其表面形貌的高低起伏,但这往往会导致信号强度不稳定和成像假象。为此,不仅需要获得样品中的化学组成与空间分布,还需同时获得样品表面的形貌信息,才能实现多功能的原位表征。在自行研制的激光解吸/电离飞行时间质谱的基础上,采用近场纳米有孔针尖离子源代替传统的远场激光聚焦,以532 nm波长激光为第一束解析激光,355 nm波长激光为后电离激光,音叉式原子力显微镜控制系统针尖与样品之间的距离维持在近场范围内,对酞菁铜镀层样品表面进行了弹坑剥蚀实验,获得了直径为550～850 nm的弹坑点阵;并对7.5 μm×7.5 μm的标准酞菁铜网格样品进行了铜离子亚微米级的高分辨率成像;此外,纳米有孔针尖离子源作为原子力显微镜的一种变体,还可同时获得成像区域的表面形貌信息,这一结合优势大大拓展了质谱技术在微纳尺度下的原位表征能力。     

Application of XPS spectral subtraction and multivariate analysis for the characterization of Ar ion beam modified polyimide surfaces

This paper presents results of a detailed X-ray photoelectron spectroscopy (XPS) characterization of complex changes at a polyimide surface resulting from Ar⁺ ion beam modification. The changes in chemical composition in the surface layer lead to formation of a layer that can act as an alignment layer for liquid crystals. The goal of this paper is to report on the result of a combination of spectral subtraction and multivariate analysis for analysis of XPS spectra. Principal component analysis (PCA), applied to curve-fitting results of difference spectra and multivariate curve resolution (MCR), applied to raw spectra, provided consistent results, and allowed for extraction of chemical anisotropy, defining factor in the ion beam (IB) alignment mechanism. This study demonstrated that more detailed chemical information about complex systems can be obtained through application of multivariate analysis to XPS spectra and curve-fits. Further, this approach can be effectively used in the characterization of various complex materials to link chemical structure to their properties.     

A comparative study of fracture strength, ultrasonic properties and chemical constituents of kidney stones

Ultrasonic properties of kidney stones were studied with a double-probe-through-transmission technique, the micro hardness was studied using the Viker indentation method and the chemical composition studied using an X-ray technique. The microhardness is found to vary with chemical composition as well as ultrasonic propagation velocity. The comparative results obtained are discussed in detail.     

A multi‐technique approach for the characterization of decorative stones and non‐destructive method for the discrimination of similar rocks

In this paper, a multi‐technique approach, at different scale of observation, is used to characterize a group of decorative stones and to permit to distinguish rocks with similar aspect but coming from different areas. In particular, the samples under study are sedimentary and metamorphic rocks, widely used as building blocks of modern and historical constructions and sculptures. The petrographic and mineralogical features of such rocks were performed by optical microscopy and Raman and Fourier transform infrared absorbance spectroscopies. These techniques permitted to obtain a complete structural, textural, and mineralogical characterization. At elemental level, the investigation was carried out by X‐ray fluorescence (XRF). In particular, XRF and Raman measurements were collected using portable instrumentations, whose advantages for the in situ analysis have been pointed out. The obtained results evidenced the high discriminant capability of the portable XRF for the decorative stones especially when this method is coupled with mineralogical and petrographic information. In this context, we propose to create a database for precious ornamental stones, which could be a starting point for a non‐destructive characterization, even useful for provenance study and/or certification of origin. Copyright © 2013 John Wiley & Sons, Ltd.     

In Vivo Laser Tomographic Imaging of Mouse Leg by Coherent Detection Imaging Method

The coherent detection imaging (CDI) technique based on the optical heterodyne detection method enables selective filtering of the directional coherent retaining emergent photons from biological tissues with a highly scattering nature. Therefore, the CDI can acquire on-axis information in the transillumination mode and use the same data-acquisition protocol and reconstruction algorithm as those in X-ray computed tomography (CT). Although the CDI-based laser CT cannot image thick subjects such as the head and chest, it can delineate subjects with a thickness up to several cm at a spatial resolution of sub-millimeters. We are planning to apply the technique to early diagnosis of rheumatoid arthritis (RA). Here, we performed an experiment using mice to confirm the feasibility. We compared in vivo CT images at the level of ankle joints of two mice, one normal and the other with collagen induced arthritis (CIA) as an RA model, and demonstrated that there occur significant discrepancies between the two distributions of image intensities, i.e., reconstructed scattering coefficients in each region of interest (ROI) prepared. We suggest that combining the morphological information with the quantitative information can be effective for early diagnosis of bone diseases and disorders such as rheumatoid arthritis.     

Analysis of degradation phenomena in ancient,traditional and improved building materials of historical monuments

A review is presented on constructive techniques plus materials and the processes involved in degradation phenomena observed in two historical monuments: the Zambujeiro dolmen (Portugal) and the Roman Aqueduct of Carthage (Tunisia). Dolmens are particularly impressive megalithic constructions for the dimensions of granite blocks. At Zambujeiro, the upright stones have undergone a catastrophic evolution after the archaeological exploitation due to accelerated weathering through a process apparently distinct from natural granite decay in nearby outcrops. The biological attack of granite minerals by lichen exudates has emphasized the hazardous character of bromine and more has been learnt about construction techniques, namely, the insertion in the mound of an impermeable clay stratum that hinders water penetration into the dolmen chamber. The characterization of original Roman ashlar blocks, including masonry and the diagnosis of Byzantine and medieval reconstruction testimonies in the Aqueduct of Carthage were the object of a detailed study by X-ray diffraction and synchrotron radiation X-ray fluorescence. Traditional constructive techniques and local construction materials were studied and successive historical, modern and recent rehabilitations were reappraised. PACS  83.80.Nb; 64.70.Kb; 78.70.En; 41.60.Ap     

基于能谱CT的材料组分彩色表征研究

基于光子计数探测器的X射线能谱CT,通过增加能谱分辨率实现了CT图像由灰度向彩色的转变,提高了材料识别能力。然而随着能谱通道数量的增加,通道中的噪声也显著增加,降低了材料识别的准确性。为充分利用能谱CT图像的稀疏性以及能谱通道之间图像的相关性,提出一种多约束窄谱CT迭代重建算法,可在降低噪声的同时有效保留图像的边缘及细节部分。进一步利用主成分分析对窄谱CT图像中的能谱信息进行估计,并建立主成分图像与R,G和B颜色分量之间的映射关系,最后获取彩色CT图像。该方法通过材料组分的彩色表征可以有效识别材料,同时降低图像中的背景噪声。仿真实验和实际实验结果验证了多约束窄谱CT迭代重建算法的有效性以及利用主成分分析进行材料组分彩色表征的可行性。     

Full-field technique for measuring the spectral evolution of reconfigurable photonic filters

This Letter demonstrates a measurement technique based on frequency-to-time mapping and coherent detection, which enables the complete (i.e., amplitude and phase) characterization of dynamically reconfigurable photonic filters. We apply this technique to a unit cell from a silicon CMOS-compatible photonic lattice filter that has a rapidly changing transfer function with an 8.33 ns update time, 120 MHz spectral resolution, and 12 GHz bandwidth. These dynamic measurements allow characterization of transients, thermal effects, filter fidelity, and other time-dependent phenomena during switching.     

The 3D characteristics of post‐traumatic syringomyelia in a rat model: a propagation‐based synchrotron radiation microtomography study

Many published literature sources have described the histopathological characteristics of post‐traumatic syringomyelia (PTS). However, three‐dimensional (3D) visualization studies of PTS have been limited due to the lack of reliable 3D imaging techniques. In this study, the imaging efficiency of propagation‐based synchrotron radiation microtomography (PB‐SRµCT) was determined to detect the 3D morphology of the cavity and surrounding microvasculature network in a rat model of PTS. The rat model of PTS was established using the infinite horizon impactor to produce spinal cord injury (SCI), followed by a subarachnoid injection of kaolin to produce arachnoiditis. PB‐SRµCT imaging and histological examination, as well as fluorescence staining, were conducted on the animals at the tenth week after SCI. The 3D morphology of the cystic cavity was vividly visualized using PB‐SRµCT imaging. The quantitative parameters analyzed by PB‐SRµCT, including the lesion and spared spinal cord tissue area, the minimum and maximum diameters in the cystic cavity, and cavity volume, were largely consistent with the results of the histological assessment. Moreover, the 3D morphology of the cavity and surrounding angioarchitecture could be simultaneously detected on the PB‐SRµCT images. This study demonstrated that high‐resolution PB‐SRµCT could be used for the 3D visualization of trauma‐induced spinal cord cavities and provides valuable quantitative data for cavity characterization. PB‐SRµCT could be used as a reliable imaging technique and offers a novel platform for tracking cavity formation and morphological changes in an experimental animal model of PTS.     

氧化物薄膜研制中的电子能谱技术

随着科学技术的不断发展，人们正在寻求更新的实用材料．金属氧化物，包括金属氧化物薄膜的各种实用材料，在工业界、信息产业界和能源开发等方面的应用前景，早已引起国内外学者的极大关注．例如，由于氧化物具有各种特殊的介电和光学性质，研究和开发基于氧化物薄膜的气敏材料非常热门．如何制备出有实用价值的各种薄膜材料，是科学家们一直关心和深入研究的课题．电子能谱技术在各种材料的基础研究和实际应用中起着重要的作用．本文以有序金属氧化物薄膜研制为例，简要评述了电子能谱技术（包括X射线光电子能谱（XPS），紫外光电子能谱（UPS），俄歇电子能谱（AES）和高分辨电子能量损失谱（HREELS）），以及低能电子衍射（LEED）等技术在氧化物薄膜材料制备和表征中的应用．