scholarly journals Модификация эмиссионной поверхности науглероженного иридиевого полевого эмиттера при адсорбции атомов бария

Author(s):  
Д.П. Бернацкий ◽  
В.Г. Павлов

Field electron microscopy was used to study the modification of the emission surface of a carbonized iridium field emitter when the concentration of barium atoms on the surface changes within the monolayer coating. When barium atoms are adsorbed at a temperature of T=300 K, no significant changes in the field electronic images of the emission surface are observed. The formation of barium islands on graphene in the region of the (100) iridium face at the annealing temperature T=1200 K was detected. At the annealing temperature T=1500 K, the barium island is dissolved and graphene is intercalated by barium atoms. The emission surface increases and becomes uniform in emission.

Author(s):  
Douglas C. Barker

A number of satisfactory methods are available for the electron microscopy of nicleic acids. These methods concentrated on fragments of nuclear, viral and mitochondrial DNA less than 50 megadaltons, on denaturation and heteroduplex mapping (Davies et al 1971) or on the interaction between proteins and DNA (Brack and Delain 1975). Less attention has been paid to the experimental criteria necessary for spreading and visualisation by dark field electron microscopy of large intact issociations of DNA. This communication will report on those criteria in relation to the ultrastructure of the (approx. 1 x 10-14g) DNA component of the kinetoplast from Trypanosomes. An extraction method has been developed to eliminate native endonucleases and nuclear contamination and to isolate the kinetoplast DNA (KDNA) as a compact network of high molecular weight. In collaboration with Dr. Ch. Brack (Basel [nstitute of Immunology), we studied the conditions necessary to prepare this KDNA Tor dark field electron microscopy using the microdrop spreading technique.


Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer

It has been shown for some time that it is possible to obtain images of small unstained proteins, with a resolution of approximately 5Å using dark field electron microscopy (1,2). Applying this technique, we have observed a uniformity in size and shape of the 2-dimensional images of pure specimens of fish protamines (salmon, herring (clupeine, Y-l) and rainbow trout (Salmo irideus)). On the basis of these images, a model for the 3-dimensional structure of the fish protamines has been proposed (2).The known amino acid sequences of fish protamines show stretches of positively charged arginines, separated by regions of neutral amino acids (3). The proposed model for protamine structure (2) consists of an irregular, right-handed helix with the segments of adjacent arginines forming the loops of the coil.


2015 ◽  
Vol 21 (S3) ◽  
pp. 963-964
Author(s):  
Peng Gao ◽  
Ryo Ishikawa ◽  
Eita Tochigi ◽  
Akihito Kumamoto ◽  
Naoya Shibata ◽  
...  

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