Automated Electron Tomography Using a Variety of Imaging Techniques and Detectors

CO2 methanation is often performed on Ni/Al2O3 catalysts, which can suffer from mass transport limitations and, therefore, decreased efficiency. Here we show the application of a hierarchically porous Ni/Al2O3 catalyst for methanation of CO2. The material has a well-defined and connected meso- and macropore structure with a total porosity of 78%. The pore structure was thoroughly studied with conventional methods, i.e., N2 sorption, Hg porosimetry, and He pycnometry, and advanced imaging techniques, i.e., electron tomography and ptychographic X-ray computed tomography. Tomography can quantify the pore system in a manner that is not possible using conventional porosimetry. Macrokinetic simulations were performed based on the measures obtained by porosity analysis. These show the potential benefit of enhanced mass-transfer properties of the hierarchical pore system compared to a pure mesoporous catalyst at industrially relevant conditions. Besides the investigation of the pore system, the catalyst was studied by Rietveld refinement, diffuse reflectance ultraviolet-visible (DRUV/vis) spectroscopy, and H2-temperature programmed reduction (TPR), showing a high reduction temperature required for activation due to structural incorporation of Ni into the transition alumina. The reduced hierarchically porous Ni/Al2O3 catalyst is highly active in CO2 methanation, showing comparable conversion and selectivity for CH4 to an industrial reference catalyst.

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Multimodal x-ray and electron microscopy of the Allende meteorite

Science Advances ◽

10.1126/sciadv.aax3009 ◽

2019 ◽

Vol 5 (9) ◽

pp. eaax3009 ◽

Cited By ~ 4

Author(s):

Yuan Hung Lo ◽

Chen-Ting Liao ◽

Jihan Zhou ◽

Arjun Rana ◽

Charles S. Bevis ◽

...

Keyword(s):

Electron Microscopy ◽

Spatial Resolution ◽

Electron Tomography ◽

Imaging Techniques ◽

Three Dimensional ◽

Functional Materials ◽

Atomic Scale ◽

Chemical Mapping ◽

X Ray ◽

Orientation Contrast

Multimodal microscopy that combines complementary nanoscale imaging techniques is critical for extracting comprehensive chemical, structural, and functional information, particularly for heterogeneous samples. X-ray microscopy can achieve high-resolution imaging of bulk materials with chemical, magnetic, electronic, and bond orientation contrast, while electron microscopy provides atomic-scale spatial resolution with quantitative elemental composition. Here, we combine x-ray ptychography and scanning transmission x-ray spectromicroscopy with three-dimensional energy-dispersive spectroscopy and electron tomography to perform structural and chemical mapping of an Allende meteorite particle with 15-nm spatial resolution. We use textural and quantitative elemental information to infer the mineral composition and discuss potential processes that occurred before or after accretion. We anticipate that correlative x-ray and electron microscopy overcome the limitations of individual imaging modalities and open up a route to future multiscale nondestructive microscopies of complex functional materials and biological systems.

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EM-stellar: benchmarking deep learning for electron microscopy image segmentation

10.1101/2020.07.15.203836 ◽

2020 ◽

Author(s):

Afshin Khadangi ◽

Thomas Boudier ◽

Vijay Rajagopal

Keyword(s):

Electron Microscopy ◽

Deep Learning ◽

Electron Tomography ◽

Imaging Techniques ◽

Small Sample ◽

Low Contrast ◽

Benchmark Analysis ◽

Exciting Opportunity ◽

Microscopy Image ◽

Block Face

AbstractThe inherent low contrast of electron microscopy (EM) datasets presents a significant challenge for rapid segmentation of cellular ultrastructures from EM data. This challenge is particularly prominent when working with high resolution big-datasets that are now acquired using electron tomography and serial block-face imaging techniques. Deep learning (DL) methods offer an exciting opportunity to automate the segmentation process by learning from manual annotations of a small sample of EM data. While many DL methods are being rapidly adopted to segment EM data no benchmark analysis has been conducted on these methods to date. We present EM-stellar, a Jupyter Notebook platform that is hosted on google Colab that can be used to benchmark the performance of a range of state-of-the-art DL methods on user-provided datasets. Using EM-Stellar we show that the performance of any DL method is dependent on the properties of the images being segmented. It also follows that no single DL method performs consistently across all performance evaluation metrics.

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Contribution of Electron Tomography to Development of Innovative Materials for Clean Energy Systems and Aeronautics

Archives of Metallurgy and Materials ◽

10.2478/amm-2013-0005 ◽

2013 ◽

Vol 58 (2) ◽

pp. 387-392 ◽

Cited By ~ 4

Author(s):

A. Kruk ◽

A. Czyrska-Filemonowicz

Keyword(s):

Quantitative Data ◽

Quantitative Measurement ◽

Electron Tomography ◽

Imaging Techniques ◽

Three Dimensional ◽

Energy Systems ◽

Clean Energy ◽

Qualitative And Quantitative ◽

Innovative Materials ◽

Electron Microscopes

The development of innovative materials for clean energy systems and aeronautics requires use of modern research methods to characterize the structure on the level from micro- to nanoscale. Modern two-dimensional imaging techniques recently available in electron microscopes allow use of tomographic methods to characterize the structure of materials. Application of modern three dimensional imaging techniques such as electron tomography allows accurate qualitative and quantitative measurement of the structure elements in the micro- and nanoscale. The electron tomography studies have been carried out for three-dimensional visualization and metrology of different materials for clean energy systems and aeronautics. Electron tomography results provided quantitative data about shape, size and distribution of the particles, complementary to those obtained by means of quantitative TEM metallography.

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Tetrahymena RIB72A and RIB72B are Microtubule Inner Proteins in the ciliary doublet microtubules

10.1101/356428 ◽

2018 ◽

Author(s):

Daniel Stoddard ◽

Ying Zhao ◽

Brian A. Bayless ◽

Long Gui ◽

Panagiota Louka ◽

...

Keyword(s):

Cell Biology ◽

High Speed ◽

Electron Tomography ◽

Imaging Techniques ◽

Structural Defects ◽

Power Stroke ◽

Basal Bodies ◽

Luminal Surface ◽

Ciliary Motility ◽

Cryo Electron Tomography

ABSTRACTDoublet and triplet microtubules are essential and highly stable core structures of centrioles, basal bodies, cilia and flagella. In contrast to dynamic cytoplasmic microtubules, their luminal surface is coated with regularly arranged Microtubule Inner Proteins (MIPs). However, the protein composition and biological function(s) of MIPs remain poorly understood. Using genetic, biochemical and imaging techniques we identified Tetrahymena RIB72A and RIB72B proteins as ciliary MIPs. Fluorescence imaging of tagged RIB72A and RIB72B showed that both proteins co-localize to Tetrahymena cilia and basal bodies, but assemble independently. Cryo-electron tomography of RIB72A and/or RIB72B knockout strains revealed major structural defects in the ciliary A-tubule involving MIP1, MIP4 and MIP6 structures. The defects of individual mutants were complementary in the double mutant. All mutants had reduced swimming speed and ciliary beat frequencies, and high-speed video imaging revealed abnormal highly curved cilia during power stroke. Our results show that RIB72A and RIB72B are crucial for the structural assembly of ciliary A-tubule MIPs and are important for proper ciliary motility.SUMMARYMicrotubule Inner Proteins (MIPs) bind to the luminal surface of highly stable microtubules. Combining cell biology and cryo-electron tomography, Stoddard et al. show that RIB72A and RIB72B are conserved MIPs in ciliary doublet microtubules and that they are important for proper ciliary motility.

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Minicells, Back in Fashion

Journal of Bacteriology ◽

10.1128/jb.00901-15 ◽

2016 ◽

Vol 198 (8) ◽

pp. 1186-1195 ◽

Cited By ~ 36

Author(s):

Madeline M. Farley ◽

Bo Hu ◽

William Margolin ◽

Jun Liu

Keyword(s):

Conformational Changes ◽

Electron Tomography ◽

Imaging Techniques ◽

Three Dimensional ◽

Model Systems ◽

Specimen Thickness ◽

Macromolecular Complexes ◽

Content Type ◽

Cellular Environment

Cryo-electron tomography (cryo-ET) has emerged as a leading technique for three-dimensional visualization of large macromolecular complexes and their conformational changes in their native cellular environment. However, the resolution and potential applications of cryo-ET are fundamentally limited by specimen thickness, preventing high-resolutionin situvisualization of macromolecular structures in many bacteria (such asEscherichia coliandSalmonella enterica). Minicells, which were discovered nearly 50 years ago, have recently been exploited as model systems to visualize molecular machinesin situ, due to their smaller size and other unique properties. In this review, we discuss strategies for producing minicells and highlight their use in the study of chemotactic signaling, protein secretion, and DNA translocation. In combination with powerful genetic tools and advanced imaging techniques, minicells provide a springboard for in-depth structural studies of bacterial macromolecular complexesin situand therefore offer a unique approach for gaining novel structural insights into many important processes in microbiology.

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Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100115055 ◽

1975 ◽

Vol 33 ◽

pp. 286-287

Author(s):

Jerome J. Paulin

Keyword(s):

Imaging Techniques ◽

Three Dimensional ◽

Posterior Pole ◽

Dimensional Structure ◽

Stereo Imaging ◽

Thin Sections ◽

Anatomical Features ◽

The Past ◽

Cellular Components ◽

Mitochondrial Reticulum

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).

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Application of Lattice Imaging Techniques to Amorphous Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113664 ◽

1975 ◽

Vol 33 ◽

pp. 8-9

Author(s):

S. R. Herd ◽

P. Chaudhari

Keyword(s):

Nearest Neighbor ◽

Random Network ◽

Imaging Techniques ◽

Network Models ◽

Accurate Method ◽

Direct Transmission ◽

Lattice Imaging ◽

Transmission Electron ◽

Lattice Planes ◽

Nearest Neighbor Distances

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.

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Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129826 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1038-1039

Author(s):

Shawn Williams ◽

Xiaodong Zhang ◽

Susan Lamm ◽

Jack Van’t Hof

Keyword(s):

Visible Light ◽

Radiation Damage ◽

Cross Section ◽

Imaging Techniques ◽

Dose Range ◽

Specimen Preparation ◽

X Rays ◽

Metaphase Chromosomes ◽

X Ray ◽

Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

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An x-ray microprobe based upon a close-coupled focal-spot / glass capillary arrangement

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133424 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1758-1759

Author(s):

D. A. Carpenter ◽

M. A. Taylor

Keyword(s):

Imaging Techniques ◽

Fluorescence Analysis ◽

High Sensitivity ◽

Specimen Preparation ◽

X Rays ◽

Glass Capillary ◽

Close Coupling ◽

X Ray ◽

Point To Point ◽

Beam Damage

The development of intense sources of x rays has led to renewed interest in the use of microbeams of x rays in x-ray fluorescence analysis. Sparks pointed out that the use of x rays as a probe offered the advantages of high sensitivity, low detection limits, low beam damage, and large penetration depths with minimal specimen preparation or perturbation. In addition, the option of air operation provided special advantages for examination of hydrated systems or for nondestructive microanalysis of large specimens.The disadvantages of synchrotron sources prompted the development of laboratory-based instrumentation with various schemes to maximize the beam flux while maintaining small point-to-point resolution. Nichols and Ryon developed a microprobe using a rotating anode source and a modified microdiffractometer. Cross and Wherry showed that by close-coupling the x-ray source, specimen, and detector, good intensities could be obtained for beam sizes between 30 and 100μm. More importantly, both groups combined specimen scanning with modern imaging techniques for rapid element mapping.

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