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词条 Electron tomography
释义

  1. BF-TEM and ADF-STEM tomography

     Different tilting methods 

  2. See also

  3. References

Electron tomography (ET) is a tomography technique for obtaining detailed 3D structures of sub-cellular macro-molecular objects. Electron tomography is an extension of traditional transmission electron microscopy and uses a transmission electron microscope to collect the data. In the process, a beam of electrons is passed through the sample at incremental degrees of rotation around the center of the target sample. This information is collected and used to assemble a three-dimensional image of the target. For biological applications, the typical resolution of ET systems[1] are in the 5–20 nm range, suitable for examining supra-molecular multi-protein structures, although not the secondary and tertiary structure of an individual protein or polypeptide.[2][3]

BF-TEM and ADF-STEM tomography

In the field of biology, bright-field transmission electron microscopy (BF-TEM) and high-resolution TEM (HRTEM) are the primary imaging methods for tomography tilt series acquisition. However, there are two issues associated with BF-TEM and HRTEM. First, acquiring an interpretable 3-D tomogram requires that the projected image intensities vary monotonically with material thickness. This condition is difficult to guarantee in BF/HRTEM, where image intensities are dominated by phase-contrast with the potential for multiple contrast reversals with thickness, making it difficult to distinguish voids from high-density inclusions.[4] Second, the contrast transfer function of BF-TEM is essentially a high-pass filter – information at low spatial frequencies is significantly suppressed – resulting in an exaggeration of sharp features. However, the technique of annular dark-field scanning transmission electron microscopy (ADF-STEM), which is typically used on material specimens,[5] more effectively suppresses phase and diffraction contrast, providing image intensities that vary with the projected mass-thickness of samples up to micrometres thick for materials with low atomic number. ADF-STEM also acts as a low-pass filter, eliminating the edge-enhancing artifacts common in BF/HRTEM. Thus, provided that the features can be resolved, ADF-STEM tomography can yield a reliable reconstruction of the underlying specimen which is extremely important for its application in material science.[6] For 3D imaging, the resolution is traditionally described by the Crowther criterion. In 2010, a 3D resolution of 0.5±0.1×0.5±0.1×0.7±0.2 nm was achieved with a single-axis ADF-STEM tomography.[7] Recently, atomic resolution in 3D electron tomography reconstructions has been demonstrated.[8][9] ADF-STEM tomography has recently been used to directly visualize the atomic structure of screw dislocations in nanoparticles.[10][11][12][13]

Different tilting methods

The most popular tilting methods are the single-axis and the dual-axis tilting methods. The geometry of most specimen holders and electron microscopes normally precludes tilting the specimen through a full 180° range, which can lead to artifacts in the 3D reconstruction of the target.[14] By using dual-axis tilting, the reconstruction artifacts are reduced by a factor of compared to single-axis tilting. However, twice as many images need to be taken. Another method of obtaining a tilt-series is the so-called conical tomography method, in which the sample is tilted, and then rotated a complete turn.[15]

See also

  • Tomography
  • Tomographic reconstruction
  • Cryo-electron tomography
  • Positron emission tomography
  • Crowther criterion
  • X-ray computed tomography
  • tomviz tomography software
  • imod tomography software

References

1. ^{{cite journal|title=The Reconstruction of a Three-Dimensional Structure from Projections and its Application to Electron Microscopy|year=1970|author1=R. A. Crowther |author2=D. J. DeRosier |author3=A. Klug |journal=Proc. R. Soc. Lond. A|volume=317|issue=1530|pages=319–340|doi=10.1098/rspa.1970.0119}}
2. ^{{Cite book | doi = 10.1007/978-0-387-69008-7| title = Electron Tomography| year = 2006| isbn = 978-0-387-31234-7| last1 = Frank| first1 = Joachim}}
3. ^{{Cite journal | doi = 10.1006/jsbi.1997.3919| pmid = 9441937| title = Dual-Axis Tomography: An Approach with Alignment Methods That Preserve Resolution| journal = Journal of Structural Biology| volume = 120| issue = 3| pages = 343–352| year = 1997| last1 = Mastronarde | first1 = D. N. }}
4. ^{{Cite journal | doi = 10.1017/S143192760550117X| title = Annular Dark Field Tomography in TEM| journal = Microscopy and Microanalysis| volume = 11| year = 2005| last1 = Bals | first1 = S. | last2 = Kisielowski | first2 = C. F. | last3 = Croitoru | first3 = M. | last4 = Tendeloo | first4 = G. V. }}
5. ^{{cite journal|author=B.D.A. Levin|display-authors=etal|title=Nanomaterial datasets to advance tomography in scanning transmission electron microscopy|journal=Scientific Data |year=2016|volume=3|issue=160041|page=160041 |doi=10.1038/sdata.2016.41|pmid=27272459|pmc=4896123|url=http://www.nature.com/articles/sdata201641|arxiv=1606.02938|bibcode=2016NatSD...360041L}}
6. ^{{Cite journal | doi = 10.1016/S0304-3991(03)00105-0| title = 3D electron microscopy in the physical sciences: The development of Z-contrast and EFTEM tomography| journal = Ultramicroscopy| volume = 96| issue = 3–4| pages = 413–431| year = 2003| last1 = Midgley | first1 = P. A. | authorlink = Paul Midgley| last2 = Weyland | first2 = M. | pmid=12871805}}
7. ^{{Cite journal | doi = 10.1063/1.3442496| title = Three-dimensional imaging of pore structures inside low-κ dielectrics| journal = Applied Physics Letters| volume = 96| issue = 22| pages = 223108| year = 2010| last1 = Xin | first1 = H. L. | last2 = Ercius | first2 = P. | last3 = Hughes | first3 = K. J. | last4 = Engstrom | first4 = J. R. | last5 = Muller | first5 = D. A. |bibcode = 2010ApPhL..96v3108X }}
8. ^{{cite journal|author=Y. Yang|display-authors=etal|title=Deciphering chemical order/disorder and material properties at the single-atom level|journal=Nature |year=2017|volume=542|issue=7639|pages=75–79 |doi=10.1038/nature21042|pmid=28150758|url=http://www.nature.com/nature/journal/v542/n7639/full/nature21042.html|arxiv=1607.02051|bibcode=2017Natur.542...75Y}}
9. ^{{Cite journal | doi = 10.1038/nature10934| title = Electron tomography at 2.4-ångström resolution| journal = Nature| volume = 483| issue = 7390| pages = 444–7| year = 2012| last1 = Scott | first1 = M. C.| last2 = Chen | first2 = C. C. | last3 = Mecklenburg | first3 = M. | last4 = Zhu | first4 = C. | last5 = Xu | first5 = R. | last6 = Ercius | first6 = P. | last7 = Dahmen | first7 = U. | last8 = Regan | first8 = B. C.| last9 = Miao | first9 = J. | pmid=22437612|bibcode = 2012Natur.483..444S }}
10. ^{{Cite journal | doi = 10.1038/nature12009| title = Three-dimensional imaging of dislocations in a nanoparticle at atomic resolution| journal = Nature| volume = 496| issue = 7443| pages = 74–77| year = 2013| last1 = Chen | first1 = C. C. | last2 = Zhu | first2 = C. | last3 = White | first3 = E. R. | last4 = Chiu | first4 = C. Y. | last5 = Scott | first5 = M. C.| last6 = Regan | first6 = B. C.| last7 = Marks | first7 = L. D. | last8 = Huang | first8 = Y. | last9 = Miao | first9 = J. |bibcode = 2013Natur.496...74C | pmid=23535594}}
11. ^{{Cite journal | doi = 10.1038/nmat2406| title = Electron tomography and holography in materials science| journal = Nature Materials| volume = 8| issue = 4| pages = 271–280| year = 2009| last1 = Midgley | first1 = P. A. | authorlink1 = Paul Midgley| last2 = Dunin-Borkowski | first2 = R. E. | authorlink2 = Rafal E. Dunin-Borkowski | pmid=19308086|bibcode = 2009NatMa...8..271M | url = http://orbit.dtu.dk/en/publications/electron-tomography-and-holography-in-materials-science(d225e463-a16b-4084-9a8e-ed62acb64bbc).html}}
12. ^{{Cite journal | doi = 10.1063/1.2213185| title = Three-dimensional imaging of nanovoids in copper interconnects using incoherent bright field tomography| journal = Applied Physics Letters| volume = 88| issue = 24| pages = 243116| year = 2006| last1 = Ercius | first1 = P. | last2 = Weyland | first2 = M. | last3 = Muller | first3 = D. A. | last4 = Gignac | first4 = L. M. |bibcode = 2006ApPhL..88x3116E }}
13. ^{{Cite journal | doi = 10.1126/science.1178583| title = Visualizing the 3D Internal Structure of Calcite Single Crystals Grown in Agarose Hydrogels| journal = Science| volume = 326| issue = 5957| pages = 1244–1247| year = 2009| last1 = Li | first1 = H.| last2 = Xin | first2 = H. L.| last3 = Muller | first3 = D. A.| last4 = Estroff | first4 = L. A. | pmid=19965470|bibcode = 2009Sci...326.1244L }}
14. ^{{cite journal|author=B.D.A. Levin|display-authors=etal|title=Nanomaterial datasets to advance tomography in scanning transmission electron microscopy|journal=Scientific Data |year=2016|volume=3|issue=160041|page=160041 |doi=10.1038/sdata.2016.41|pmid=27272459|pmc=4896123|url=http://www.nature.com/articles/sdata201641|arxiv=1606.02938|bibcode=2016NatSD...360041L}}
15. ^{{Cite journal | pmid = 18417694| pmc = 3844767| year = 2008| author1 = Zampighi| first1 = G. A.| title = Conical electron tomography of a chemical synapse: Polyhedral cages dock vesicles to the active zone| journal = Journal of Neuroscience| volume = 28| issue = 16| pages = 4151–60| last2 = Fain| first2 = N| last3 = Zampighi| first3 = L. M.| last4 = Cantele| first4 = F| last5 = Lanzavecchia| first5 = S| last6 = Wright| first6 = E. M.| doi = 10.1523/JNEUROSCI.4639-07.2008}}

3 : Electron microscopy|Multidimensional signal processing|Condensed matter physics
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