scholarly journals Quantifying Morphology and Diffusion Properties of Mesoporous Carbon From High-Fidelity 3D Reconstructions

2019 ◽  
Vol 25 (4) ◽  
pp. 891-902 ◽  
Author(s):  
Wu Wang ◽  
Artur Svidrytski ◽  
Di Wang ◽  
Alberto Villa ◽  
Horst Hahn ◽  
...  
Keyword(s):  
Mesoporous Carbon ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Morphological Description ◽  
Reconstruction Technique ◽  
Reconstruction Algorithms ◽  
Scanning Transmission ◽  
Dimensional Reconstruction ◽  
Iterative Reconstruction Technique ◽  
Diffusion Properties

AbstractA reliable quantitative analysis in electron tomography, which depends on the segmentation of the three-dimensional reconstruction, is challenging because of constraints during tilt-series acquisition (missing wedge) and reconstruction artifacts introduced by reconstruction algorithms such as the Simultaneous Iterative Reconstruction Technique (SIRT) and Discrete Algebraic Reconstruction Technique (DART). We have carefully evaluated the fidelity of segmented reconstructions analyzing a disordered mesoporous carbon used as support in catalysis. Using experimental scanning transmission electron microscopy (STEM) tomography data as well as realistic phantoms, we have quantitatively analyzed the effect on the morphological description as well as on diffusion properties (based on a random-walk particle-tracking simulation) to understand the role of porosity in catalysis. The morphological description of the pore structure can be obtained reliably both using SIRT and DART reconstructions even in the presence of a limited missing wedge. However, the measured pore volume is sensitive to the threshold settings, which are difficult to define globally for SIRT reconstructions. This leads to noticeable variations of the diffusion coefficients in the case of SIRT reconstructions, whereas DART reconstructions resulted in more reliable data. In addition, the anisotropy of the determined diffusion properties was evaluated, which was significant in the presence of a limited missing wedge for SIRT and strongly reduced for DART.

Three-Dimensional reconstruction of isolated centrosomes by automated electron tomography

1994 ◽  
Vol 52 ◽  
pp. 310-311
Author(s):  
M.B. Braunfeld ◽  
M. Moritz ◽  
B.M. Alberts ◽  
J.W. Sedat ◽  
D.A. Agard
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
Vital Role ◽  
Complex Nature ◽  
Animal Cells ◽  
Microtubule Organizing Center ◽  
Nucleation Sites ◽  
Dimensional Reconstruction ◽  
Organizing Center ◽  
Resolution Model

In animal cells, the centrosome functions as the primary microtubule organizing center (MTOC). As such the centrosome plays a vital role in determining a cell's shape, migration, and perhaps most importantly, its division. Despite the obvious importance of this organelle little is known about centrosomal regulation, duplication, or how it nucleates microtubules. Furthermore, no high resolution model for centrosomal structure exists.We have used automated electron tomography, and reconstruction techniques in an attempt to better understand the complex nature of the centrosome. Additionally we hope to identify nucleation sites for microtubule growth.Centrosomes were isolated from early Drosophila embryos. Briefly, after large organelles and debris from homogenized embryos were pelleted, the resulting supernatant was separated on a sucrose velocity gradient. Fractions were collected and assayed for centrosome-mediated microtubule -nucleating activity by incubating with fluorescently-labeled tubulin subunits. The resulting microtubule asters were then spun onto coverslips and viewed by fluorescence microscopy.

scholarly journals A Survey of the Use of Iterative Reconstruction Algorithms in Electron Microscopy

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
C. O. S. Sorzano ◽  
J. Vargas ◽  
J. Otón ◽  
J. M. de la Rosa-Trevín ◽  
J. L. Vilas ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
Iterative Algorithms ◽  
Projection Methods ◽  
Particle Analysis ◽  
Reconstruction Algorithms ◽  
Large Families ◽  
Key Steps

One of the key steps in Electron Microscopy is the tomographic reconstruction of a three-dimensional (3D) map of the specimen being studied from a set of two-dimensional (2D) projections acquired at the microscope. This tomographic reconstruction may be performed with different reconstruction algorithms that can be grouped into several large families: direct Fourier inversion methods, back-projection methods, Radon methods, or iterative algorithms. In this review, we focus on the latter family of algorithms, explaining the mathematical rationale behind the different algorithms in this family as they have been introduced in the field of Electron Microscopy. We cover their use in Single Particle Analysis (SPA) as well as in Electron Tomography (ET).

scholarly journals Novel nonlinear reconstruction method with grey-level quantisation units for electron tomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Norio Baba ◽  
Kenji Kaneko ◽  
Misuzu Baba
Keyword(s):  
Cross Section ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Back Projection ◽  
Grey Level ◽  
Discrete Processing ◽  
Structural Image ◽  
Tomography Reconstruction

AbstractWe report a new computed tomography reconstruction method, named quantisation units reconstruction technique (QURT), applicable to electron and other fields of tomography. Conventional electron tomography methods such as filtered back projection, weighted back projection, simultaneous iterative reconstructed technique, etc. suffer from the ‘missing wedge’ problem due to the limited tilt-angle range. QURT demonstrates improvements to solve this problem by recovering a structural image blurred due to the missing wedge and substantially reconstructs the structure even if the number of projection images is small. QURT reconstructs a cross-section image by arranging grey-level quantisation units (QU pieces) in three-dimensional image space via unique discrete processing. Its viability is confirmed by model simulations and experimental results. An important difference from recently developed methods such as discrete algebraic reconstruction technique (DART), total variation regularisation—DART, and compressed sensing is that prior knowledge of the conditions regarding the specimen or the expected cross-section image is not necessary.

Three-Dimensional Imaging of Shear Band Produced by ECAP Process in Al-Ag Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 603-608
Author(s):  
Koji Inoke ◽  
Kenji Kaneko ◽  
Z. Horita
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Tomography ◽  
Shear Bands ◽  
Three Dimensional ◽  
Angular Pressing ◽  
Ecap Process ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Matrix

A significant change in microstructure occurs during the application of severe plastic deformation (SPD) such as by equal-channel angular pressing (ECAP). In this study, intense plastic strain was imposed on an Al-10.8wt%Ag alloy by the ECAP process. The amount of strain was controlled by the numbers of passes. After 1 pass of ECAP, shear bands became visible within the matrix. With increasing numbers of ECAP passes, the fraction of shear bands was increased. In this study, the change in microstructures was examined by three-dimensional electron tomography (3D-ET) in transmission electron microscopy (TEM) or scanning transmission electron microscopy (STEM). With this 3D-ET method, it was possible to conduct a precise analysis of the sizes, widths and distributions of the shear bands produced by the ECAP process. It is demonstrated that the 3D-ET method is promising to understand mechanisms of microstructural refinement using the ECAP process.

A modified discrete tomography for improving the reconstruction of unknown multi-gray-level material in the `missing wedge' situation

2018 ◽  
Vol 25 (6) ◽  
pp. 1847-1859 ◽  
Author(s):  
Jianhong Liu ◽  
Zhiting Liang ◽  
Yong Guan ◽  
Wenbin Wei ◽  
Haobo Bai ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Iteration Process ◽  
Reconstruction Technique ◽  
Morphological Operations ◽  
Algebraic Reconstruction Technique ◽  
Discrete Tomography ◽  
Boundary Extraction ◽  
X Ray ◽  
Dimensional Reconstruction

Full angular rotational projections cannot always be acquired in tomographic reconstructions because of the limited space in the experimental setup, leading to the `missing wedge' situation. In this paper, a recovering `missing wedge' discrete algebraic reconstruction technique algorithm (rmwDART) has been proposed to solve the `missing wedge' problem and improve the quality of the three-dimensional reconstruction without prior knowledge of the material component's number or the material's values. By using oversegmentation, boundary extraction and mathematical morphological operations, `missing wedge' artifact areas can be located. Then, in the iteration process, by updating the located areas and regions, high-quality reconstructions can be obtained from the simulations, and the reconstructed images based on the rmwDART algorithm can be obtained from soft X-ray nano-computed tomography experiments. The results showed that there is the potential for discrete tomography.

Research on Key Techniques of Virtual Arthroscopic Knee Surgery Training System

2012 ◽  
Vol 220-223 ◽  
pp. 2338-2341
Author(s):  
Jin Fang Li ◽  
Han Wu He ◽  
Hao Huang ◽  
Jun Lei
Keyword(s):  
Medical Image ◽  
Three Dimensional ◽  
Training System ◽  
Virtual Surgery ◽  
Reconstruction Technique ◽  
Arthroscopic Knee Surgery ◽  
Surgery Training ◽  
Dimensional Reconstruction ◽  
Arthroscopic Knee ◽  
Key Techniques

This paper discussed the three-dimensional reconstruction technique from medical image, the interaction technology, and some other key techniques needed to be solved urgently of the virtual surgery training system. On the basis of research results, we built a surgery training system.

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