透射电子显微镜(Transmission Electron Microscope,TEM)提供了超高的空间分辨率和多样化的微区分析方法,是纳米地质学研究的重要表征手段之一。运用TEM技术研究矿物时,由于地质样品的高度复杂性和强烈非均质性,使得实验测试过程复杂而...透射电子显微镜(Transmission Electron Microscope,TEM)提供了超高的空间分辨率和多样化的微区分析方法,是纳米地质学研究的重要表征手段之一。运用TEM技术研究矿物时,由于地质样品的高度复杂性和强烈非均质性,使得实验测试过程复杂而困难。文章探索了一套适用于地质样品的TEM分析测试流程。首先根据样品特性,选择合适的样品制备方法,重点介绍了粉末制备法、离子减薄法及聚焦离子束法;然后进行目标矿物的定位,提出了一种扫描电镜(Scanning Electron Microscope,SEM)+TEM组合定位法;接着进行包括明场像、暗场像、高分辨像、电子衍射花样等不同类型图像的获取,着重说明了各种图像的成像原理、拍摄过程、注意事项和实验技巧;最后是选定关注的微区,测试元素组成及分布情况,并与常用的微区成分分析仪器进行对比,从而说明TEM成分分析的适用范围及优点。展开更多
Phenolic compounds and their derivatives have been found in industrial wastewater, which pose threats to the natural environment. Ordered mesoporous carbon(OMC) has been identified as an ideal adsorbent possessing hig...Phenolic compounds and their derivatives have been found in industrial wastewater, which pose threats to the natural environment. Ordered mesoporous carbon(OMC) has been identified as an ideal adsorbent possessing high specific surface area and large pore volume to alleviate these pollutants. A novel ordered mesoporous carbon was prepared using COK-19 template with the cubic Fm3 m structure for the first time. Ordered mesoporous silica COK-19 was synthesized and reported in 2015. Sucrose as the carbon precursor was impregnated into the mesopores of silica and converted to carbon through carbonization process using sulfuric acid as a catalyst. Ordered mesoporous carbon was obtained after the removal of silica framework using hydrofluoric acid. Boric acid was employed for the preparation of OMCs with tunable pore sizes in the range of 6.9–16.6 nm. Several characterization techniques such as nitrogen adsorption–desorption isotherms, transmission electron microscope(TEM), Fourier transform infrared spectroscopy, Boehm titration and elemental analysis were employed to characterize the OMCs. The pore size analysis and TEM images confirmed that OMC has replicated the mesostructure of the COK-19. Results obtained from adsorption kinetics and isotherms suggest that the Pseudo-second-order model and Langmuir isotherm well described the experimental data.展开更多
Despite the wide availability and usage of Gatan’s DigitalMicrograph software in the electron microscopy community for image recording and analysis, nonlinear least-squares fitting in DigitalMicrograph is less straig...Despite the wide availability and usage of Gatan’s DigitalMicrograph software in the electron microscopy community for image recording and analysis, nonlinear least-squares fitting in DigitalMicrograph is less straightforward. This work presents a ready-to-use tool, the DMPFIT software package, written in DigitalMicrograph script and C++ language, for nonlinear least-squares fitting of the intensity distribution of atomic columns in atomic-resolution transmission electron microscopy (TEM) images with a general two-dimensional (2D) Gaussian model. Applications of the DMPFIT software are demonstrated both in atomic-resolution conventional coherent TEM (CTEM) images recorded by the negative spherical aberration imaging technique and in high angle annular dark field (HAADF) scanning TEM (STEM) images. The implemented peak-finding algorithm based on the periodicity of 2D lattices enables reliable and convenient atomic-scale metrology as well as intuitive presentation of the resolved atomic structures.展开更多
New advances within the recently rediscovered field of Compressed Sensing (CS) have opened for a great variety of new possibilities in the field of image reconstruction and more specifically in medical image reconstru...New advances within the recently rediscovered field of Compressed Sensing (CS) have opened for a great variety of new possibilities in the field of image reconstruction and more specifically in medical image reconstruction. In this work, a new approach using a CS-based algorithm is proposed and used in order to solve limited-angle problems (LAPs), like the ones that typically occur in computed tomography or electron microscope. This approach is based on a variant of the Robbins-Monro stochastic approximation procedure, developed by Egaziarian, using regularization by a spatially adaptive filter. This proposal consists on filling the gaps of missing or unobserved data with random noise and enabling a spatially adaptive denoising filter to regularize the data and reveal the underlying topology. This method was tested on different 3D transmission electron microscope datasets that presented different missing data artifacts (e.g, wedge or cone shape). The test results show a great potential for solving LAPs using the proposed technique.展开更多
文摘透射电子显微镜(Transmission Electron Microscope,TEM)提供了超高的空间分辨率和多样化的微区分析方法,是纳米地质学研究的重要表征手段之一。运用TEM技术研究矿物时,由于地质样品的高度复杂性和强烈非均质性,使得实验测试过程复杂而困难。文章探索了一套适用于地质样品的TEM分析测试流程。首先根据样品特性,选择合适的样品制备方法,重点介绍了粉末制备法、离子减薄法及聚焦离子束法;然后进行目标矿物的定位,提出了一种扫描电镜(Scanning Electron Microscope,SEM)+TEM组合定位法;接着进行包括明场像、暗场像、高分辨像、电子衍射花样等不同类型图像的获取,着重说明了各种图像的成像原理、拍摄过程、注意事项和实验技巧;最后是选定关注的微区,测试元素组成及分布情况,并与常用的微区成分分析仪器进行对比,从而说明TEM成分分析的适用范围及优点。
基金supported by the University of Louisiana at Lafayette and Louisiana Board of Regents (Nos.LEQSFRD-C-15 and LEQSF-ENH-TR-32)
文摘Phenolic compounds and their derivatives have been found in industrial wastewater, which pose threats to the natural environment. Ordered mesoporous carbon(OMC) has been identified as an ideal adsorbent possessing high specific surface area and large pore volume to alleviate these pollutants. A novel ordered mesoporous carbon was prepared using COK-19 template with the cubic Fm3 m structure for the first time. Ordered mesoporous silica COK-19 was synthesized and reported in 2015. Sucrose as the carbon precursor was impregnated into the mesopores of silica and converted to carbon through carbonization process using sulfuric acid as a catalyst. Ordered mesoporous carbon was obtained after the removal of silica framework using hydrofluoric acid. Boric acid was employed for the preparation of OMCs with tunable pore sizes in the range of 6.9–16.6 nm. Several characterization techniques such as nitrogen adsorption–desorption isotherms, transmission electron microscope(TEM), Fourier transform infrared spectroscopy, Boehm titration and elemental analysis were employed to characterize the OMCs. The pore size analysis and TEM images confirmed that OMC has replicated the mesostructure of the COK-19. Results obtained from adsorption kinetics and isotherms suggest that the Pseudo-second-order model and Langmuir isotherm well described the experimental data.
基金Financial support from the German Research Foundation(SFB917)is acknowledgedOpen Access funding enabled and organized by Projekt DEAL.
文摘Despite the wide availability and usage of Gatan’s DigitalMicrograph software in the electron microscopy community for image recording and analysis, nonlinear least-squares fitting in DigitalMicrograph is less straightforward. This work presents a ready-to-use tool, the DMPFIT software package, written in DigitalMicrograph script and C++ language, for nonlinear least-squares fitting of the intensity distribution of atomic columns in atomic-resolution transmission electron microscopy (TEM) images with a general two-dimensional (2D) Gaussian model. Applications of the DMPFIT software are demonstrated both in atomic-resolution conventional coherent TEM (CTEM) images recorded by the negative spherical aberration imaging technique and in high angle annular dark field (HAADF) scanning TEM (STEM) images. The implemented peak-finding algorithm based on the periodicity of 2D lattices enables reliable and convenient atomic-scale metrology as well as intuitive presentation of the resolved atomic structures.
文摘New advances within the recently rediscovered field of Compressed Sensing (CS) have opened for a great variety of new possibilities in the field of image reconstruction and more specifically in medical image reconstruction. In this work, a new approach using a CS-based algorithm is proposed and used in order to solve limited-angle problems (LAPs), like the ones that typically occur in computed tomography or electron microscope. This approach is based on a variant of the Robbins-Monro stochastic approximation procedure, developed by Egaziarian, using regularization by a spatially adaptive filter. This proposal consists on filling the gaps of missing or unobserved data with random noise and enabling a spatially adaptive denoising filter to regularize the data and reveal the underlying topology. This method was tested on different 3D transmission electron microscope datasets that presented different missing data artifacts (e.g, wedge or cone shape). The test results show a great potential for solving LAPs using the proposed technique.
