scholarly journals Cryo-EM with sub–1 Å specimen movement

Science ◽  
2020 ◽  
Vol 370 (6513) ◽  
pp. 223-226 ◽  
Author(s):  
Katerina Naydenova ◽  
Peipei Jia ◽  
Christopher J. Russo
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Speed ◽  
Three Dimensional ◽  
Water Layer ◽  
Information Loss ◽  
Particle Movement ◽  
Support Design ◽  
Quality Movement ◽  
Subsequent Deformation

Most information loss in cryogenic electron microscopy (cryo-EM) stems from particle movement during imaging, which remains poorly understood. We show that this movement is caused by buckling and subsequent deformation of the suspended ice, with a threshold that depends directly on the shape of the frozen water layer set by the support foil. We describe a specimen support design that eliminates buckling and reduces electron beam–induced particle movement to less than 1 angstrom. The design allows precise foil tracking during imaging with high-speed detectors, thereby lessening demands on cryostage precision and stability. It includes a maximal density of holes, which increases throughput in automated cryo-EM without degrading data quality. Movement-free imaging allows extrapolation to a three-dimensional map of the specimen at zero electron exposure, before the onset of radiation damage.

Image quality vs data obtainment in biological electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 42-43
Author(s):  
J. E. Johnson
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Image Quality ◽  
High Speed ◽  
Early Period ◽  
Early Years ◽  
Fluorescent Screen ◽  
Embedding Medium

In the early years of biological electron microscopy, scientists had their hands full attempting to describe the cellular microcosm that was suddenly before them on the fluorescent screen. Mitochondria, Golgi, endoplasmic reticulum, and other myriad organelles were being examined, micrographed, and documented in the literature. A major problem of that early period was the development of methods to cut sections thin enough to study under the electron beam. A microtome designed in 1943 moved the specimen toward a rotary “Cyclone” knife revolving at 12,500 RPM, or 1000 times as fast as an ordinary microtome. It was claimed that no embedding medium was necessary or that soft embedding media could be used. Collecting the sections thus cut sounded a little precarious: “The 0.1 micron sections cut with the high speed knife fly out at a tangent and are dispersed in the air. They may be collected... on... screens held near the knife“.

Unusual Rapidity of Electron Beam Transient Tempering

1986 ◽  
Vol 80 ◽  
Author(s):  
Anjum Tauqir ◽  
Peter R. Strutt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Thermal Treatment ◽  
Rapid Solidification ◽  
High Speed ◽  
Defect Cluster ◽  
High Concentration ◽  
Transmission Electron ◽  
Nucleation Sites

AbstractElectron beam rapid solidification of molybdenum-base high speed steels results in quenched-in metastable phases containing a high concentration of alloying elements. Thermal reprocessing of such material by momentary interaction with the electron beam results in decomposition of martensite at a rate ≈ 100 times faster than that occurring during conventional thermal treatment. It is postulated that this arises from a high concentration of 'defect cluster nucleation sites' during the rapid up-quenching. The product of short thermal treatment is a dispersion of 2–5 nm very fine precipitates identified using transmission electron microscopy as MC type carbides.

SEM of polymer materials

1987 ◽  
Vol 45 ◽  
pp. 426-429
Author(s):  
Linda C. Sawyer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Essential Feature ◽  
Three Dimensional ◽  
Image Formation ◽  
Sem Analysis ◽  
Polymer Materials ◽  
Specimen Preparation ◽  
Scanning Electron

Scanning electron microscopy (SEM) has become an analytical tool widely used in universities, industrial laboratories and modern plants in applications ranging from fundamental research and applied research to quality control. The SEM provides important and insightful observations, in the form of three dimensional images of bulk materials and surfaces, which provide input to conduct process-structure-properties studies of polymer materials. SEM analysis requires knowledge of the instruments, image formation and specimen preparation methods.Consideration must be given to the interaction of the electron beam with the specimen, image formation and the effect of the electron beam on the specimen, e.g. beam damage. Scanning electron microscopy has been described and SEM of polymers has been reviewed. The essential feature of a scanning microscope is that the image is formed point by point, by scanning a probe across the specimen. The probe of an SEM is a focused electron beam and a detected signal is displayed as a TV type image.

Nanoseconds Double-Frame and Streak Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 180-181 ◽  
Author(s):  
Oleg Bostanjoglo ◽  
Jochen Kornitzky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Laser Radiation ◽  
High Speed ◽  
Ccd Camera ◽  
Transmission Electron ◽  
Film Specimen ◽  
532 Nm ◽  
Modern Tool

Material processing and synthesis is increasingly done by lasers. In order to apply this modern tool effectively, the laser-induced physical processes must be well known. As transmission electron microscopy is a powerful method to study the structure of the treated material, it seemed worthwhile to extend this technique for fast phase transitions, as are triggered by laser radiation. High-speed TEM may be realized either by pulsing the detector /l/ or the illuminating electron beam. The latter technique is more convenient and is described here.Fig. 1 shows a high-speed TEM designed for taking either double frame images (exposure/ repetition times ≿ 10 ns/≿ 50 ns) or streak images of transitions induced by a laser in the thin film specimen. It consists of a modified commercial TEM, an attached Q-switched (FWHM 50 ns), frequency-doubled (532 nm) Nd:YAG laser for treating the specimen, and electronics for electron beam pulsing and image storage. The TEM is equipped with focusing/deflecting optics for the laser radiation, an electron beam pulser generating either the exposure times for double frame pictures or the streak, and an image shifter. The image detector is a proximity focusing double stage MicroChannel Plate (MCP)/scintillator assembly. A CCD camera transfers the image to a PC-backed digitizing and frame grabbing card. The components are synchronized by a specially designed logic unit /2/.

Thermal- and acoustic-wave techniques in scanning electron microscopy

1986 ◽  
Vol 64 (9) ◽  
pp. 1238-1246 ◽  
Author(s):  
Ludwig Josef Balk
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Acoustic Wave ◽  
Three Dimensional ◽  
Acoustic Microscopy ◽  
Wave Form ◽  
Time Resolved ◽  
In Situ Experiments ◽  
Scanning Electron

Since their introduction in 1980, thermal- and acoustic-wave techniques utilizing electron-beam excitation, denoted in the following as scanning electron acoustic microscopy (SEAM), have developed to include methods in the realm of scanning electron microscopy (SEM), giving additional and important information on material parameters compared with other SEM techniques. However, the SEAM method still has shortcomings, both theoretically and experimentally. New theories have to consider various principal sound-generation mechanisms, especially for semiconductors, ceramics, and ferromagnets. Furthermore, they must include three-dimensional and time-resolved calculations. From experimental evidence there is obviously the need for additional consideration of nonlinear signal generation. The theoretical discussion has to be supported by experiments; both phase analysis of the SEAM signal with respect to the electron-beam wave form and evaluation of the temporal SEAM behaviour are important for revealing information about the specimen. With special detectors, in situ experiments can be carried out for varying process parameters, as shown for the investigation of steel sheets. The SEAM performance has to be compared to other SEM modes by simultaneous experiments, especially for applications to semiconductors. Finally, extension to gigahertz frequencies and use of tomographic methods should increase the importance of SEAM in future.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

1977 ◽  
Vol 35 ◽  
pp. 570-571 ◽  
Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Biological Tissues ◽  
High Voltage Electron Microscopy ◽  
Transverse Tubular System ◽  
Peroxidase Reaction ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

Electron Microscopy of Cytoplasmic Contractile Proteins

1978 ◽  
Vol 36 (3) ◽  
pp. 606-614 ◽  
Author(s):  
T.D. Pollard ◽  
P. Maupin
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Three Dimensional ◽  
Uranyl Acetate ◽  
Contractile Proteins ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Cytoplasmic Matrix ◽  
Computer Image Processing ◽  
Nonmuscle Cells

In this paper we review some of the contributions that electron microscopy has made to the analysis of actin and myosin from nonmuscle cells. We place particular emphasis upon the limitations of the ultrastructural techniques used to study these cytoplasmic contractile proteins, because it is not widely recognized how difficult it is to preserve these elements of the cytoplasmic matrix for electron microscopy. The structure of actin filaments is well preserved for electron microscope observation by negative staining with uranyl acetate (Figure 1). In fact, to a resolution of about 3nm the three-dimensional structure of actin filaments determined by computer image processing of electron micrographs of negatively stained specimens (Moore et al., 1970) is indistinguishable from the structure revealed by X-ray diffraction of living muscle.

Sign in / Sign up

Export Citation Format

Share Document