Cooling-induced wrinkling of thin crystals of biological macromolecules can be prevented by using molybdenum grids

1992 ◽  
Vol 50 (1) ◽  
pp. 520-521
Author(s):  
Robert M. Glaeser
Keyword(s):  
High Resolution ◽  
Signal To Noise Ratio ◽  
Data Retrieval ◽  
Biological Macromolecules ◽  
Tilt Axis ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Rate Of Success ◽  
High Degree

It is an important requirement of high resolution electron diffraction and electron microscopy of thin crystals of biological macromolecules that the specimen be flat (i.e. planar) to one degree or less over distances of one micrometer or more. This high degree of specimen flatness is required in order to collect diffraction patterns and images at high tilt angles and high resolution. Imperfect flatness causes the diffraction spots which are perpendicular to the tilt axis to become streaked or blurred, while the spots parallel to the tilt axis remain sharp. If the specimen wrinkling, or mosaic angular spread, is too severe, the diffraction spots overlap one another to make a continuum, and data retrieval becomes impossible (see Figure 3, for an example). Even before that point is reached, the broadening of the diffraction spots makes it increasingly difficult to obtain accurate background-subtracted diffraction intensities, and the signal-to-noise ratio in the computed Fourier transform of high resolution images is severely decreased. In some preparations of thin protein crystals the stringent requirements for specimen flatness can be met with a reasonable rate of success. In the case of bacteriorhodopsin, prepared as large singlecrystal sheets by detergent-induced fusion of the native purple membrane of Halobacterium halobium, the frequency of success is normally very low.

Atomic structure of YB56 studied by digital high-resolution electron microscopy and electron diffraction

2001 ◽  
Vol 16 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Takeo Oku ◽  
Jan-Olov Bovin ◽  
Iwami Higashi ◽  
Takaho Tanaka ◽  
Yoshio Ishizawa
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Charge Coupled Device ◽  
X Ray ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Simulated Images

Atomic positions for Y atoms were determined by using high-resolution electron microscopy and electron diffraction. A slow-scan charge-coupled device camera which had high linearity and electron sensitivity was used to record high-resolution images and electron diffraction patterns digitally. Crystallographic image processing was applied for image analysis, which provided more accurate, averaged Y atom positions. In addition, atomic disordering positions in YB56 were detected from the differential images between observed and simulated images based on x-ray data, which were B24 clusters around the Y-holes. The present work indicates that the structure analysis combined with digital high-resolution electron microscopy, electron diffraction, and differential images is useful for the evaluation of atomic positions and disordering in the boron-based crystals.

Quantitative analysis of low-dose high-resolution images and diffraction patterns from zeolites using a slow-scan CCD camera

1993 ◽  
Vol 51 ◽  
pp. 670-671
Author(s):  
M. Pan ◽  
P.A. Crozier
Keyword(s):  
High Resolution ◽  
Molecular Sieves ◽  
Structural Damage ◽  
Low Dose ◽  
Signal To Noise Ratio ◽  
Ccd Camera ◽  
Real Space ◽  
High Signal ◽  
Resolution Electron ◽  
Diffraction Patterns

Zeolites are an important class of low-density aluminosilicates framework structures with applications to the field of catalysis and molecular sieves. In order to understand die origin of die unique properties of these materials and hence optimize their performance, it is essential to have a detailed description of their structures. Zeolite structure is often described in terms of the secondary building unit (SBU) which is a specific configuration of the SiO4 tetrahedrons. Structure determination of zeolites is then reduced to determine the types of SB Us and their connectivities when forming the 3-D framework structure.It has been recognized that zeolites undergo rapid structural damage under electron beam irradiation. The use of a slow-scan CCD camera to record low-dose high resolution electron microscope (HREM) images from zeolites with the combination with real-space averaging techniques has been shown to be successful in obtaining the averaged unit cell with high signal-to-noise ratio (SNR).

Modulated Structure of Bi1.8Sr2.0Rh1.6Ox

2007 ◽  
Vol 336-338 ◽  
pp. 818-821
Author(s):  
Kunio Yubuta ◽  
Satoshi Okada ◽  
Yuzuru Miyazaki ◽  
Ichiro Terasaki ◽  
Tsuyoshi Kajitani
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Layered Crystal ◽  
Structural Analogue ◽  
Modulated Structure ◽  
Incident Electron Beam ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns

We have investigated the modulated structure of the misfit-layered crystal Bi1.8Sr2.0Rh1.6Ox by means of electron diffraction and high-resolution electron microscopy. This compound consists of two interpenetrating subsystems of a hexagonal RhO2 sheet and a distorted four-layered rock-salt-type (Bi,Sr)O block. Both subsystems have common a-, c-axes and β-angles with a = 5.28 Å, c = 29.77 Å and β = 93.7º. On the other hand, the crystal structure is incommensurated parallel to the b-axes, among which b1 = 3.07 Å for the RhO2 sheet and b2 = 4.88 Å for the (Bi,Sr)O block. The misfit ratio, b1/b2 ~ 0.63, characterizes the structural analogue as [Bi1.79Sr1.98Oy]0.63[RhO2]. This compound has two modulation vectors, i.e., q1 = – a* + 0.63b1* and q2 = 0.17b1* + c*, and the superspace group is assigned as the Cc(1β0, 0μ1)-type from the electron diffraction patterns. High-resolution images taken with the incident electron beam parallel to the a- and c-axes clearly show displacive as well as compositional modulations.

Modulated structure of Ag2SnO3 studied by high-resolution electron microscopy

2000 ◽  
Vol 56 (3) ◽  
pp. 363-368 ◽  
Author(s):  
Takeo Oku ◽  
Anna Carlsson ◽  
Jan-Olov Bovin ◽  
Christer Svensson ◽  
L. Reine Wallenberg ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Modulated Structure ◽  
Resolution Electron ◽  
Orthorhombic Cell ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Linear Coordination

The modulated structure of Ag2SnO3, disilver tin trioxide, was investigated by high-resolution electron microscopy and electron diffraction along four different directions. Electron diffraction showed an incommensurate one-dimensional modulated structure with a modulation wavevector of 1/6.4a*. High-resolution images showed a large number of superstructure domains with the size range 10–100 nm and orientations related by hexagonal rotation. The modulation was determined to be displacements along the c axis of the Ag atoms both in octahedral and linear coordination. An approximate structure model with a commensurate sixfold superstructure, with an orthorhombic cell (P212121, a = 2.922, b = 1.267, c = 0.562 nm), is proposed. Calculated images and electron diffraction patterns, based on this model, agree well with experimental observations.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution

1991 ◽  
Vol 49 ◽  
pp. 540-541
Author(s):  
Kenneth H. Downing ◽  
Hu Meisheng ◽  
Hans-Rudolf Went ◽  
Michael A. O'Keefe
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Atomic Resolution ◽  
Dimensional Structure ◽  
Structure Information ◽  
Resolution Electron ◽  
Scattering Effects ◽  
High Resolution Images ◽  
Effects Of Radiation

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.

The Contribution of Phonon-Scattered Electrons to High-Resolution Electron Micrographs of Crystals

1990 ◽  
Vol 48 (1) ◽  
pp. 62-63
Author(s):  
H. Kohl
Keyword(s):  
High Resolution ◽  
Spherical Aberration ◽  
High Resolution Electron Microscopy ◽  
Static Potential ◽  
Qualitative Comparison ◽  
The Past ◽  
Resolution Electron ◽  
High Resolution Images ◽  
High Resolution Electron Micrographs ◽  
Extract Information

High-Resolution Electron Microscopy is able to determine structures of crystals and interfaces with a spatial resolution of somewhat less than 2 Å. As the image is strongly dependent on instrumental parameters, notably the defocus and the spherical aberration, the interpretation of micrographs necessitates a comparison with calculated images. Whereas one has often been content with a qualitative comparison of theory with experiment in the past, one is currently striving for quantitative procedures to extract information from the images [1,2]. For the calculations one starts by assuming a static potential, thus neglecting inelastic scattering processes.We shall confine the discussion to periodic specimens. All electrons, which have only been elastically scattered, are confined to very few directions, the Bragg spots. In-elastically scattered electrons, however, can be found in any direction. Therefore the influence of inelastic processes on the elastically (= Bragg) scattered electrons can be described as an attenuation [3]. For the calculation of high-resolution images this procedure would be correct only if we had an imaging energy filter capable of removing all phonon-scattered electrons. This is not realizable in practice. We are therefore forced to include the contribution of the phonon-scattered electrons.

Combined Experimentaland Theoretical Determination of the Atomic Structure of the (310) Twin in NB

1991 ◽  
Vol 238 ◽  
Author(s):  
Geoffrey H. Campbells ◽  
Wayne E. King ◽  
Stephen M. Foiles ◽  
Peter Gumbsch ◽  
Manfred Rühle
Keyword(s):  
High Resolution ◽  
Theoretical Models ◽  
High Resolution Electron Microscopy ◽  
Interatomic Potentials ◽  
Image Simulation ◽  
Theoretical Determination ◽  
Atomic Structures ◽  
Resolution Electron ◽  
High Resolution Images

ABSTRACTA (310) twin boundary in Nb has been fabricated by diffusion bonding oriented single crystals and characterized using high resolution electron microscopy. Atomic structures for the boundary have been predicted using different interatomic potentials. Comparison of the theoretical models to the high resolution images has been performed through image simulation. On the basis of this comparison, one of the low energy structures predicted by theory can be ruled out.

The ultrastructure of coccoliths from the marine alga Emiliania huxleyi (Lohmann) Hay and Mohler: an ultra-high resolution electron microscope study

1983 ◽  
Vol 219 (1215) ◽  
pp. 111-117 ◽  
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Emiliania Huxleyi ◽  
Growth Patterns ◽  
Lattice Image ◽  
Nucleation Sites ◽  
Resolution Electron ◽  
Lattice Images ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns

The calcite coccoliths from the alga Emiliania huxleyi (Lohmann) Hay and Mohler have been studied by ultra-high resolution electron microscopy. This paper describes the two different types of structure observed, one in the upper elements, the other in the basal plate, or lower element. The former consisted of small, microdomain structures of 300-500 Å (1 Å = 10 -10 m) in length with no strong orientation. At places along these elements, and particularly in the junction between stem and head pieces, triangular patterns of lattice fringes were observed indicating multiple nucleation sites in the structure. In contrast, the lower element consisted of a very thin single crystalline sheet of calcite which could be resolved into a two dimensional lattice image, shown by a computer program that is capable of simulating electron diffraction patterns and lattice images to be a [421] zone of calcite. A possible mechanism for these growth patterns in the formation of coccoliths is discussed, together with the relevance of such mechanisms to biomineralization generally.

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