scholarly journals Eleven tungsten atom cluster labels: high-resolution, site-specific probes for electron microscopy.

1990 ◽  
Vol 38 (12) ◽  
pp. 1787-1793 ◽  
Author(s):  
J F Hainfeld ◽  
C J Foley ◽  
L E Maelia ◽  
J J Lipka
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Sulfonyl Chloride ◽  
Sulfhydryl Groups ◽  
Tungsten Atom ◽  
Site Specific ◽  
Atom Cluster ◽  
Derivatives Of

Two derivatives of a tungstate cluster containing 11 tungsten atoms (W11PO39SiR4-) have been synthesized which enable them to be covalently attached to biomolecules at specific sites. The tungstate cluster is 1.0 nm in diameter, electron dense, and visible in the electron microscope. One derivative is a W11-sulfonyl chloride, reactive with amines and sulfhydryls. The second compound is a W11-thiosulfonate which can be used to label sulfhydryl groups. These new labels are beam resistant and provide significantly higher resolution then most other electron microscopy (EM) markers. Labeling of the protein albumin is described as an example.

A Base Specific Single Heavy Atom Stain for Electron Microscopy

1972 ◽  
Vol 30 ◽  
pp. 184-185
Author(s):  
J. P. Langmore ◽  
N. R. Cozzarelli ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Elastic Scattering ◽  
Heavy Atom ◽  
High Vacuum ◽  
Heavy Atoms ◽  
Large Movement ◽  
Base Sequencing ◽  
Scanning Electron

A system has been developed to allow highly specific derivatization of the thymine bases of DNA with mercurial compounds wich should be visible in the high resolution scanning electron microscope. Three problems must be completely solved before this staining system will be useful for base sequencing by electron microscopy: 1) the staining must be shown to be highly specific for one base, 2) the stained DNA must remain intact in a high vacuum on a thin support film suitable for microscopy, 3) the arrangement of heavy atoms on the DNA must be determined by the elastic scattering of electrons in the microscope without loss or large movement of heavy atoms.

High Resolution Scanning Electron Microscopy

1991 ◽  
Vol 49 ◽  
pp. 478-479
Author(s):  
David Joy ◽  
James Pawley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Electron Probe ◽  
Impact Point ◽  
Interaction Volume ◽  
Scanning Electron

The scanning electron microscope (SEM) builds up an image by sampling contiguous sub-volumes near the surface of the specimen. A fine electron beam selectively excites each sub-volume and then the intensity of some resulting signal is measured. The spatial resolution of images made using such a process is limited by at least three factors. Two of these determine the size of the interaction volume: the size of the electron probe and the extent to which detectable signal is excited from locations remote from the beam impact point. A third limitation emerges from the fact that the probing beam is composed of a finite number of discrete particles and therefore that the accuracy with which any detectable signal can be measured is limited by Poisson statistics applied to this number (or to the number of events actually detected if this is smaller).

Comparative Studies of the Degradation of Several Zeolites Under Electron Irradiation

1987 ◽  
Vol 111 ◽  
Author(s):  
D. R. Acosta ◽  
O. Guzman ◽  
P. Del Angel ◽  
J. Dominguez
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Electron Irradiation ◽  
Comparative Studies ◽  
Structural Characteristics ◽  
High Resolution Electron Microscopy ◽  
Degradation Process ◽  
Optical Parameters ◽  
Resolution Electron

High resolution electron microscopy has proven to be a powerful technique to determine structural characteristics of zeolites (l–2),symmetry variations and identification of several kind of defects.Together with ideal projected potential images, the microscopist usually finds in electron micrographs the influence of electro-optical parameters and alterations of the crystallinity of the material under electron irradiation. One of the purposes of this workis to contributetothe understanding of the degradation process of zeolites under electron irradiation in the electron microscope and in this way, discriminate when it is possible, what is reliable information recorded in the images obtained in high resolution conditions.

scholarly journals Vitrification of Y zeolite and its effects on HREM images

1986 ◽  
Vol 44 ◽  
pp. 774-775
Author(s):  
R. Csencsits
Keyword(s):  
Electron Microscopy ◽  
Computer Simulation ◽  
Electron Microscope ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Systematic Investigation ◽  
Y Zeolite ◽  
Y Zeolites ◽  
Transmission Electron ◽  
Resolution Electron

High resolution electron microscopy (HREM) is a valuable technique for studying catalytic zeolite systems because it gives direct information about the structure and defects present in the structure. The difficulty with doing an HREM study on zeolites is that they become amorphous under electron irradiation. This work is a systematic investigation of the damage of Y zeolites in the transmission electron microscope (TEM); the goals of this study are to determine the mechanism for electron damage and to access the effects of damage in Y zeolites on their HREM images using computer simulation.

The Use of Phase and Amplitude Information of Reconstructed Exit Waves

1997 ◽  
Vol 3 (S2) ◽  
pp. 1029-1030
Author(s):  
H.W. Zandbergen
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Field Emission ◽  
Software Package ◽  
Dynamic Range ◽  
Ccd Camera ◽  
Phase Object ◽  
High Resolution Images

Exit waves can be reconstructed from through focus series of HREM images or by off-axis holography [1]. We have applied the through focus method to reconstruct exit waves, using algorithms developed by Van Dyck and Coene [2]. Electron microscopy was performed with a Philips CM30ST electron microscope with a field emission gun operated at 300 kV. The high resolution images were recorded using a Tietz software package and a 1024x1024 pixel Photometrix CCD camera having a dynamic range of 12 bits. The reconstructions were done using 15-20 images with focus increments of 5.2 nm. The resulting exit waves were corrected posteriorly for the three fold astigmatism.The exit wave is complex; consequently it contains phase and amplitude. Since in the very thin regions the specimen acts as a thin phase object, such a thin area will show little contrast, an example of which is shown in Figure 1.

Image analysis of 2-D Na,K-ATPase crystals maintained in vitreous ice

1988 ◽  
Vol 46 ◽  
pp. 396-397
Author(s):  
Manoj Misra ◽  
Harry C. Beall ◽  
Kenneth A. Taylor ◽  
H.P. Ting-Beall
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Electron Microscope ◽  
High Resolution ◽  
Optical Diffraction ◽  
Native State ◽  
Amorphous Ice ◽  
Ordered Arrays ◽  
Minimal Dose ◽  
Molecular Description

The molecular description of the Na,K-ATPase in the native state at high-resolution is required for the detailed description of the mechanism by which the active transport of Na and K ions occurs. Our efforts, therefore, are directed toward obtaining this molecular description by means of electron microscopy of ordered arrays of Na,K-ATPase molecules preserved in the frozen-hydrated state in amorphous ice.The procedure for crystallization of Na,K-ATPase was similar to that of Mohraz et al. Electron microscope grids for cryo-microscopy were prepared essentially as described by Dubochet et al. Frozen-hydrated specimens were examined in the Philips 420 electron microscope using a Gatan model 626 Cryotransfer system and cooling holder. Micrographs were recorded at 36000X under minimal dose conditions. Electron micrographs of frozen-hydrated membranes were screened initially by optical diffraction and examined for the presence of 4-6 rows of crystal lattice without any discernible visual disorder.

A HREM study of V/Al2O3 interface

1992 ◽  
Vol 50 (1) ◽  
pp. 146-147
Author(s):  
Y. Ikuhara ◽  
P. Pirouz ◽  
A. H. Heuer ◽  
S. Yadavalli ◽  
C. P. Flynn
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Substrate Temperature ◽  
Molecular Beam ◽  
High Resolution Electron Microscopy ◽  
Interface Structure ◽  
Cross Sectional ◽  
Plan View ◽  
Resolution Electron

The interface structure between vanadium and the R-plane of sapphire (α-Al2O3) was studied by conventional and cross-sectional high resolution electron microscopy (HREM) to clarify the atomic structure of the interface.A 57 nm thick vanadium film was deposited on the (1102) (R) plane of sapphire by molecular beam epitaxy (MBE) at a substrate temperature of 920 K in a vacuum of 10-10torr. The HREM observations of the interface were done from three directions: two cross-sectional views (parallel to [0221]Al2O3 and [1120]Al2O3) and a plan view (parallel to [2201]Al2O3) by a top-entry JEOL 4000EX electron microscope (400 kV).

High Resolution Cryo-Electron Microscopy Sheds A New Light Upon Biomembrane Architecture

1990 ◽  
Vol 48 (1) ◽  
pp. 494-495
Author(s):  
Kume P. Nahoaki ◽  
Yuba D. Akiko ◽  
Yoshizawa C. Akiyasu ◽  
Sato B. Satoshi ◽  
Fujiyoshi Yoshinori
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
Photosynthetic Bacterium ◽  
Chromatium Vinosum ◽  
Irradiation Damage ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
Cooling Mechanism ◽  
Chicken Erythrocytes

Cryo-electron microscopy, together with the rapid cryo-fixation technique, has made it possible to observe chemically unfixed unstained specimens under a transmission electron microscope. Aoki et al. constructed a new cryo-stage in order to reduce irradiation damage upon biological specimens further by cooling them with liquid helium. It was also designed to eliminate shaking of specimens as much as possible by the sophisticated mounting and the refined cooling mechanism of the stage. The stage has proved to achieve a higher contrast and higher resolution of images than a commonly-used cryo-stage cooled solely by liquid nitrogen does. This high resolution cryo-electron microscope (HiRCEM) was originally developed aiming at the improvement of resolution in structural analysis of proteins or nucleic acids, but it has turned out to be quite useful for detecting the architecture of biomembranes as well. This is due to the existence of phosphorus atoms of phospholipids which are heavier than C, H, O, N atoms abundant within biomembranes, and also due to the great optical depth of the membrane where it is aligned parallel to the electron beams.We have examined several kinds of biomembranes as well as the synthesized liposomes under HiRCEM. Among them were the plasma membrane of human erythrocytes (ghosts), the nuclear membrane of chicken erythrocytes, the endoplasmic reticular membrane of rat nerve cells, the chromatophore membrane of a photosynthetic bacterium Chromatium vinosum , the thylakoid membrane of spinach chloroplasts and the envelope of influenza type A virus (PR8 & X31). Liposomes we employed were synthesized from the 2:1 mixture of phosphatidylcholine and cholesterol.

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