Methylamine vanadate (nanovan) negative stain

1994 ◽  
Vol 52 ◽  
pp. 132-133
Author(s):  
James F. Hainfeld ◽  
Daniel Safer ◽  
Joseph S. Wall ◽  
Martha Simon ◽  
Beth Lin ◽  
...  
Keyword(s):  
Electron Beam ◽  
Low Dose ◽  
Biological Molecules ◽  
Positive Staining ◽  
Signal To Noise ◽  
Negative Stain ◽  
Beam Attenuation ◽  
Coarse Grains ◽  
Lower Contrast

Uranyl and tungstate compounds have found favor as negative stains because of their high scattering power relative to biological molecules. However, other properties, such as specimen preservation, resistance to alterations or crystallization in the electron beam, and signal to noise (S/N) ratio, are also important. It may be that lower density materials may have advantages in these areas. A new negative stain, methylamine vanadate, CH3 NH2.VO3 ("NanoVan"), offers a near physiological pH of 8, similar to phosphotungstate (pH 7) with much smoother background. It is also very stable in the electron beam with minimal granulation at a dose of l04 el / nm2 . The resolution obtainable with vanadate appears to be comparable to uranyl at low dose, but superior at higher dose where uranyl forms coarse grains (see Fig. 1). Problems with uranyl such as unwanted positive staining and need for pH below 4 can be avoided. The lower contrast permits use of thicker stain embedment for better preservation and less flattening without excessive beam attenuation.

Image reconstruction of low and high dose micrographs of negatively stained glutamine synthetase

1978 ◽  
Vol 36 (2) ◽  
pp. 8-9 ◽  
Author(s):  
J. Frank ◽  
W. Goldfarb ◽  
M. Kessel
Keyword(s):  
Glutamine Synthetase ◽  
Low Dose ◽  
Random Distribution ◽  
Biological Molecules ◽  
High Dose ◽  
Radiation Level ◽  
E Coli ◽  
Negative Stain ◽  
Unit Cells ◽  
Preliminary Communication

Recent studies of biological specimens with long range crystalline order have demonstrated a significant improvement in resolution when the radiation level is of the order of 0.5e/Å2 and care is taken to sustain the specimen in an inert medium such as glucose rather than negative stain. A large class of biological molecules exists, however, which do not form crystalline arrays and where the population exhibits a random distribution of projected views.In a preliminary communication we have demonstrated the possibility of applying a computer averaging procedure to such negatively stained individual molecules which produces the equivalent result to that of averaging over a number of unit cells in a crystal lattice. The present study extends these methods to assess the effect of electron dosage on negatively stained protein molecules by a comparison of averages of high and low dose micrographs of the same particles.The protein chosen for study is the enzyme glutamine synthetase isolated from E. coli and purified according to Valentine.

Removal of inelastically scattered electrons substantially increases phase contrast on frozen-hydrated molecules

1987 ◽  
Vol 45 ◽  
pp. 652-653
Author(s):  
John P. Langmore ◽  
Brian D. Athey
Keyword(s):  
Electron Diffraction ◽  
Phase Contrast ◽  
Low Dose ◽  
Dark Field ◽  
Biological Structure ◽  
Bright Field ◽  
Low Contrast ◽  
Negative Stain ◽  
The Difference ◽  
Better Than

Although electron diffraction indicates better than 0.3nm preservation of biological structure in vitreous ice, the imaging of molecules in ice is limited by low contrast. Thus, low-dose images of frozen-hydrated molecules have significantly more noise than images of air-dried or negatively-stained molecules. We have addressed the question of the origins of this loss of contrast. One unavoidable effect is the reduction in scattering contrast between a molecule and the background. In effect, the difference in scattering power between a molecule and its background is 2-5 times less in a layer of ice than in vacuum or negative stain. A second, previously unrecognized, effect is the large, incoherent background of inelastic scattering from the ice. This background reduces both scattering and phase contrast by an additional factor of about 3, as shown in this paper. We have used energy filtration on the Zeiss EM902 in order to eliminate this second effect, and also increase scattering contrast in bright-field and dark-field.

Correlation averaging of two-dimensional crystals: basic strategy and refinements

1986 ◽  
Vol 44 ◽  
pp. 136-139
Author(s):  
W. Baumeister ◽  
R. Rachel ◽  
R. Guckenberger ◽  
R. Hegerl
Keyword(s):  
Low Dose ◽  
Signal To Noise Ratio ◽  
Real Space ◽  
Fourier Domain ◽  
Two Dimensional ◽  
Signal To Noise ◽  
Unit Cells ◽  
Lateral Displacements ◽  
Established Technique ◽  
Crystalline Array

IntroductionCorrelation averaging (CAV) is meanwhile an established technique in image processing of two-dimensional crystals /1,2/. The basic idea is to detect the real positions of unit cells in a crystalline array by means of correlation functions and to average them by real space superposition of the aligned motifs. The signal-to-noise ratio improves in proportion to the number of motifs included in the average. Unlike filtering in the Fourier domain, CAV corrects for lateral displacements of the unit cells; thus it avoids the loss of resolution entailed by these distortions in the conventional approach. Here we report on some variants of the method, aimed at retrieving a maximum of information from images with very low signal-to-noise ratios (low dose microscopy of unstained or lightly stained specimens) while keeping the procedure economical.

A case of potential radiation recall dermatitis induced by chemotherapy, following low-dose total-skin electron beam therapy

2019 ◽  
Vol 29 (6) ◽  
pp. 671-672 ◽  
Author(s):  
Carl Lamoureux ◽  
Emilie Gerard ◽  
Nora Ouhabrache ◽  
Feyrouz Toukal ◽  
Anne Pham-Ledard ◽  
...  
Keyword(s):  
Electron Beam ◽  
Low Dose ◽  
Radiation Recall ◽  
Electron Beam Therapy ◽  
Radiation Recall Dermatitis ◽  
Recall Dermatitis

scholarly journals Low-dose, phase-contrast mammography with high signal-to-noise ratio

2016 ◽  
Vol 7 (2) ◽  
pp. 381 ◽  
Author(s):  
Lukas B. Gromann ◽  
Dirk Bequé ◽  
Kai Scherer ◽  
Konstantin Willer ◽  
Lorenz Birnbacher ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Low Dose ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Signal To Noise ◽  
Noise Ratio

scholarly journals Preserving quality of fresh cut watermelon cubes for vending distribution by low-dose electron beam processing

Food Control ◽  
2017 ◽  
Vol 72 ◽  
pp. 367-371 ◽  
Author(s):  
Bianca Smith ◽  
Adrienne Ortega ◽  
Shima Shayanfar ◽  
Suresh D. Pillai
Keyword(s):  
Electron Beam ◽  
Low Dose ◽  
Electron Beam Processing ◽  
Fresh Cut

scholarly journals DETERMINATION OF ELECTRON BEAM CHARGING CONDITIONS OF OXIDES AT LOW ENERGY IN THE LOW DOSE RANGE

1989 ◽  
Vol 50 (C6) ◽  
pp. C6-174-C6-174
Author(s):  
M. VALENZA ◽  
P. GIRARD ◽  
B. PISTOULET
Keyword(s):  
Electron Beam ◽  
Low Dose ◽  
Dose Range ◽  
Low Energy

Electron-beam radiation effects on the structure and properties of polypropylene at low dose rates

2018 ◽  
Vol 29 (6) ◽  
Author(s):  
Heng-Ti Wang ◽  
Hai-Qing Jiang ◽  
Rong-Fang Shen ◽  
Xiao-Jun Ding ◽  
Cong Zhang ◽  
...  
Keyword(s):  
Electron Beam ◽  
Radiation Effects ◽  
Low Dose ◽  
Structure And Properties ◽  
Beam Radiation ◽  
Dose Rates ◽  
Electron Beam Radiation
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