scholarly journals Hydrogen properties and charges in a sub-1.2 Å resolution cryo-EM structure revealed by a cold field emission beam

2021 ◽  
Author(s):  
Saori Maki-Yonekura ◽  
Keisuke Kawakami ◽  
Tasuku Hamaguchi ◽  
Kiyofumi Takaba ◽  
Koji Yonekura
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Image Data ◽  
Hydrogen Atoms ◽  
Atom Type ◽  
Contrast Transfer Function ◽  
Emission Beam ◽  
Resolution Single ◽  
Standard Protein ◽  
Resolution Structure

The cold field emission (CFE) beam produces the less-attenuated contrast transfer function of electron microscopy, thereby enhancing high-resolution signals and this particularly benefits higher-resolution single particle cryogenic electron microscopy. Here, we present a sub-1.2 Å resolution structure of a standard protein sample, apoferritin. Image data were collected with the CFE beam in a high-throughput scheme while minimizing beam tilt deviations from the coma-free axis. A difference map reveals positive densities for most hydrogen atoms in the core region of the protein complex including those in water molecules, while negative densities around acidic amino-acid side chains likely represent negative charges. The position of the hydrogen densities depends on parent bonded-atom type, which is validated by an estimated level of coordinate errors.

scholarly journals Visualization of biological macromolecules at near-atomic resolution: cryo-electron microscopy comes of age

2019 ◽  
Vol 75 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Alok K. Mitra
Keyword(s):  
Electron Microscopy ◽  
Structural Biology ◽  
Atomic Resolution ◽  
Particle Analysis ◽  
Biological Macromolecules ◽  
Single Particles ◽  
Cryo Electron Microscopy ◽  
Electron Microscopes ◽  
Resolution Single ◽  
Resolution Structure

Structural biology is going through a revolution as a result of transformational advances in the field of cryo-electron microscopy (cryo-EM) driven by the development of direct electron detectors and ultrastable electron microscopes. High-resolution cryo-EM images of isolated biomolecules (single particles) suspended in a thin layer of vitrified buffer are subjected to powerful image-processing algorithms, enabling near-atomic resolution structures to be determined in unprecedented numbers. Prior to these advances, electron crystallography of two-dimensional crystals and helical assemblies of proteins had established the feasibility of atomic resolution structure determination using cryo-EM. Atomic resolution single-particle analysis, without the need for crystals, now promises to resolve problems in structural biology that were intractable just a few years ago.

A New Image Processing Technique for STEM

1974 ◽  
Vol 32 ◽  
pp. 432-433
Author(s):  
Yasushi Kokubo ◽  
Hirotami Koike ◽  
Teruo Someya
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Scanning Electron Microscopy ◽  
Elastic Scattering ◽  
Field Emission ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Energy Analyzer ◽  
Scanning Microscope ◽  
Scanning Electron

One of the advantages of scanning electron microscopy is the capability for processing the image contrast, i.e., the image processing technique. Crewe et al were the first to apply this technique to a field emission scanning microscope and show images of individual atoms. They obtained a contrast which depended exclusively on the atomic numbers of specimen elements (Zcontrast), by displaying the images treated with the intensity ratio of elastically scattered to inelastically scattered electrons. The elastic scattering electrons were extracted by a solid detector and inelastic scattering electrons by an energy analyzer. We noted, however, that there is a possibility of the same contrast being obtained only by using an annular-type solid detector consisting of multiple concentric detector elements.

Dynamical Scattering in Crystalline Biological Specimens. I. Criteria of Validity for Scattering Approximations

1975 ◽  
Vol 33 ◽  
pp. 192-193
Author(s):  
Robert M. Glaeser ◽  
Bing K. Jap
Keyword(s):  
Biological Sciences ◽  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Born Approximation ◽  
Materials Science ◽  
Image Data ◽  
Dynamical Effect ◽  
Crystallographic Structure ◽  
Electron Microscope Image

The dynamical scattering effect, which can be described as the failure of the first Born approximation, is perhaps the most important factor that has prevented the widespread use of electron diffraction intensities for crystallographic structure determination. It would seem to be quite certain that dynamical effects will also interfere with structure analysis based upon electron microscope image data, whenever the dynamical effect seriously perturbs the diffracted wave. While it is normally taken for granted that the dynamical effect must be taken into consideration in materials science applications of electron microscopy, very little attention has been given to this problem in the biological sciences.

New challenges to image processing posed by cryo-Electron microscopy of single particles

1991 ◽  
Vol 49 ◽  
pp. 422-423
Author(s):  
Joachim Frank
Keyword(s):  
Electron Microscopy ◽  
Phase Contrast ◽  
Particle Orientation ◽  
Single Particles ◽  
Contrast Transfer Function ◽  
Virtual Absence ◽  
Cryo Electron Microscopy ◽  
Spatial Frequencies ◽  
New Challenges ◽  
Particle Images

Compared with images of negatively stained single particle specimens, those obtained by cryo-electron microscopy have the following new features: (a) higher “signal” variability due to a higher variability of particle orientation; (b) reduced signal/noise ratio (S/N); (c) virtual absence of low-spatial-frequency information related to elastic scattering, due to the properties of the phase contrast transfer function (PCTF); and (d) reduced resolution due to the efforts of the microscopist to boost the PCTF at low spatial frequencies, in his attempt to obtain recognizable particle images.

Limits for high-resolution electron microscopy of inorganic materials?

1987 ◽  
Vol 45 ◽  
pp. 4-5
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
Spherical Aberration ◽  
High Resolution Electron Microscopy ◽  
Inorganic Materials ◽  
Atomic Scale ◽  
Resolution Limit ◽  
Contrast Transfer Function ◽  
Existing Problems ◽  
Resolution Electron ◽  
Electron Microscopes

The era of atomic-resolution electron microscopy has finally arrived. In virtually all inorganic materials, including oxides, metals, semiconductors and ceramics, it is possible to image individual atomic columns in low-index zone-axis projections. A whole host of important materials’ problems involving defects and departures from nonstoichiometry on the atomic scale are waiting to be tackled by the new generation of intermediate voltage (300-400keV) electron microscopes. In this review, some existing problems and limitations associated with imaging inorganic materials are briefly discussed. The more immediate problems encountered with organic and biological materials are considered elsewhere.Microscope resolution. It is less than a decade since the state-of-the-art, commercially available TEM was a 200kV instrument with a spherical aberration coefficient of 1.2mm, and an interpretable resolution limit (ie. first zero crossover of the contrast transfer function) of 2.5A.

Recent Progress and Plans in Computer-Controlled High Resolution Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 154-155
Author(s):  
W.J. de Ruijter ◽  
Peter Rez ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
Digital Processing ◽  
High Resolution Electron Microscopy ◽  
Objective Lens ◽  
Linear Filter ◽  
Contrast Transfer Function ◽  
Image Displacement ◽  
Spatially Resolved ◽  
Wide Range ◽  
On Line

Digital computers are becoming widely recognized as standard accessories for electron microscopy. Due to instrumental innovations the emphasis in digital processing is shifting from off-line manipulation of electron micrographs to on-line image acquisition, analysis and microscope control. An on-line computer leads to better utilization of the instrument and, moreover, the flexibility of software control creates the possibility of a wide range of novel experiments, for example, based on temporal and spatially resolved acquisition of images or microdiffraction patterns. The instrumental resolution in electron microscopy is often restricted by a combination of specimen movement, radiation damage and improper microscope adjustment (where the settings of focus, objective lens stigmatism and especially beam alignment are most critical). We are investigating the possibility of proper microscope alignment based on computer induced tilt of the electron beam. Image details corresponding to specimen spacings larger than ∼20Å are produced mainly through amplitude contrast; an analysis based on geometric optics indicates that beam tilt causes a simple image displacement. Higher resolution detail is characterized by wave propagation through the optical system of the microscope and we find that beam tilt results in a dispersive image displacement, i.e. the displacement varies with spacing. This approach is valid for weak phase objects (such as amorphous thin films), where transfer is simply described by a linear filter (phase contrast transfer function) and for crystalline materials, where imaging is described in terms of dynamical scattering and non-linear imaging theory. In both cases beam tilt introduces image artefacts.

Blue Emitting BaAl2O4:Ce3+ Nanophosphors with High Color Purity and Brightness for White LEDs

2019 ◽  
Vol 25 (6) ◽  
pp. 1466-1470 ◽  
Author(s):  
Rituparna Chatterjee ◽  
Subhajit Saha ◽  
Karamjyoti Panigrahi ◽  
Uttam Kumar Ghorai ◽  
Gopes Chandra Das ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Sol Gel ◽  
Blue Emission ◽  
Diffraction Field ◽  
White Leds ◽  
Display Devices ◽  
Transmission Electron ◽  
Structure Morphology ◽  
The Impact

AbstractIn this work, strongly blue emitting Ce3+-activated BaAl2O4 nanophosphors were successfully synthesized by a sol–gel technique. The crystal structure, morphology, and microstructure of the nanophosphors have been studied by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The photoluminescence spectra show the impact of concentration variation of Ce3+ on the photoluminescence emission of the phosphor. These nanophosphors display intense blue emission peaking at 422 nm generated by the Ce3+ 5d → 4f transition under 350 nm excitation. Our results reveal that this nanophosphor has the capability to take part in the emergent domain of solid-state lighting and field-emission display devices.

Sign in / Sign up

Export Citation Format

Share Document