Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

Periodic Extension in Optical Diffraction Analysis

1982 ◽  
Vol 40 ◽  
pp. 428-429
Author(s):  
R. Gronsky ◽  
C.S. Murty
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Considerable Increase ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Diffraction Spectrum ◽  
Optical Bench ◽  
Instrumental Performance ◽  
Resolution Electron ◽  
Diffraction Effects

Although the more traditional applications of optical diffractograms in high resolution electron microscopy are related to determining instrumental performance, a significant advantage can also be achieved with this technique in the analysis of fine microstructural detail. Optical microdiffraction utilizes a field-limiting aperture in the optical bench system to selectively obtain the diffraction spectrum of specific segments of high resolution negatives, with a considerable increase in spatial resolution. Unfortunately the diffraction effects from the sampling aperture itself often interfere with the interpretation of results

On the interpretation of electron diffraction patterns from materials containing planar boundaries: the intergrowth tungsten bronzes

1990 ◽  
Vol 429 (1876) ◽  
pp. 91-117 ◽  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
General Interest ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Diffraction Patterns

Materials containing planar boundaries are of general interest and complete understanding of their structures is important. When direct imaging of the boundaries by, for instance, high-resolution electron microscopy, is impracticable, details of their structure and arrangement may be obtained from electron diffraction patterns. Such patterns are discussed in terms of those from intergrowth tungsten bronzes as specific examples. Fourier-transform calculations for proposed structures have been made to establish, in conjunction with optical-diffraction analogues, the features of the far-field diffraction patterns. These results have been compared with diffraction patterns obtained experimentally by transmission electron microscopy. The aim of the study, to show that the arrangement of the boundaries in these complicated phases can be deduced from their diffraction patterns without the need for high-resolution imaging, has been achieved. The steps to be taken to make these deductions are set out.

High Resolution Electron Microscopy of a Novel Zeolite

1997 ◽  
Vol 3 (S2) ◽  
pp. 441-442
Author(s):  
P.A. Crozier ◽  
I.Y. Chan ◽  
C.Y. Chen ◽  
L.W. Finger ◽  
R.C. Medrud ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
High Adsorption ◽  
Structural Units ◽  
X Ray ◽  
Resolution Electron ◽  
Crystal Structural

Low-dose high resolution electron microscopy (HREM) is a useful technique for elucidating the structure of zeolites. In recent years a number of zeolite structures have been solved using combinations of different characterization techniques including adsorption measurements, powder x-ray diffraction and low-dose high resolution electron microscopy (for example see ref. 2). We have used these techniques to study the structure of a novel zeolite material. However, great care must be exercised when interpreting data from these techniques in terms of crystal structural units. In this particular case, the structure was recently determined using single crystal x-ray diffraction and showed some surprises.Details of the synthesis of this zeolite are given elsewhere. The high adsorption capacity suggested that this zeolite possessed two interpenetrating channels (either a 10 and a 12 ring or two 12 ring channels). X-ray powder diffraction showed the material to be monoclinic with a= 18.5Å, b= 13.4 Å, c= 7.6 Å β = 101.5°).

Molecular imaging of Organo-Calcium salts by High Resolution Electron Microscopy and Image Processing

1990 ◽  
Vol 48 (1) ◽  
pp. 590-591
Author(s):  
G. Miller ◽  
J.R. Fryer ◽  
W. Kunath ◽  
K. Weiss
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Unit Cell ◽  
Recording Device ◽  
Resolution Electron

Unfortunatly Wolfgang Kunath died January 1990High resolution electron microscopy and image processing are being used to determine the molecular packing within the crystal unit cell of the, organic-azo calcium salt. Due to the beam sensitive nature of the organic moiety which contains both aromatic and and aliphatic components, low dose techniques were used. This concisted of, searching the sample in the diffraction mode to find single crystals exibiting point like reflection to at least .2nm resolution, (fig. 1). Focusing and astigmatism correction was performed by moving the beam of the crystal (off axis). The beam was then moved on axis and a series of four, 10 e/A images taken, (fig. 2). Images were primarily recorded using an on line T.V. recording device. These images were then available for processing using the Semper image processing system. Two crystal orientations were found. Type 1 consisted of thin plate like crystals up to 5um diameter and generally 10nm to 20nm thick. Type 2 were thicker crystals with a 3.2nm lattice spacing. The power specrta of the first low dose images were calculated to asses the quality of the of the structural information present. For the type 1 crystal the power spectrum had to show at least second order reflections in two directions ( fig. 3 ). Type 2 crystals showed the 3.2nm reflection often down to the fith order. These crystals also showed parallel side bands corresponding to a d-spacing of about .8nm. With these results the unit cell was found to be tetragonal with a= .78nm b= 3.2nm c= .78nm. In accordance with the diffraction patterns exibited.

scholarly journals Low Dose High-Resolution Electron Microscopy (HREM) of Poly(3,4-ethylene dioxythiophene) (PEDOT) Films

2011 ◽  
Vol 17 (S2) ◽  
pp. 1452-1453
Author(s):  
J Wu ◽  
D Martin
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

High-resolution electron microscopy of disordered LiFeO2

1984 ◽  
Vol 42 ◽  
pp. 430-431
Author(s):  
Nobuo Tanaka ◽  
J.M. Cowley
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Diffuse Scattering ◽  
Fine Powder ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Lithium Ferrite ◽  
Clustering Model ◽  
Resolution Electron

The disordered structure of lithium ferrite (α-LiFeO2) has been investigated in X-ray and electron diffraction techniques. The characteristic short range order (SRO) diffuse scattering was commonly interpreted by the clustering model. The SRO state can be described by interconnecting two kinds of clusters (Fig. 1). Alternatively, it may be interpreted in terms of microdomains of some ordered structures.In the present study, the specimen was investigated with high resolution electron microscopy and optical diffraction technique. The techniquescould give the information about the SRO state in a direct way. The material investigated was α-LiFeO2 in the form of a fine powder dispersed on a holey carbon grid.Fig. 2 shows electron diffraction patterns of the specimen in the <001> and <110> observing directions. The locus of the diffuse scattering does not exactly fit with the formula, cosπh + cosπk + cosπℓ = 0, which was derived from SRO arrangement of Li and Fe ions inside the clusters. This fact suggests the existance of “inter-cluster” ordering.

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