PubMed Health⌕ Search

Biomedical subjects

F Zemlin

Publications and source records attributed to F Zemlin.

22 records · Page 2Linked to original sources
PubMed1985

Molecular resolution electron micrographs of monolamellar paraffin crystals.

A liquid helium-cooled cryoelectron microscope, operated to expose the specimen to only a very low electron dose, was used to obtain structural images of monolamellar n-tetratetracontane (n-C44H90) crystals at 0.25-nanometer resolution. These results are in contrast to earlier predictions that such extremely beam-sensitive materials could not be studied directly at this level of detail. Analysis of the resultant lattice images gives direct evidence for crystal bending as well as direct visualization of edge dislocations in this material.

Crystallography↗
PubMed1984

Electron imaging of crotoxin complex thin crystal at 3.5 A.

Crotoxin complex forms thin crystals which are suitable for electron crystallographic analysis. We have used a 100 kV electron microscope equipped with a superconducting lens to image this crystal embedded in glucose. Optical diffraction analysis of the micrographs show unambiguously a structural resolution of 3.9 A which has not been obtained with the conventional microscope at room temperature. A density map with a nominal resolution of 3.5 A has been synthesized from these images by computer processing techniques.

Animals↗
PubMed1978

Radiation exposure and recognition of electron microscopic images of protamine at high resolution.

The effect of radiation exposure on visual recognition of individual macromolecules of the protein protamine was examined using high resolution electron microscopy in scanning transmission, fixed beam transmission, dark field and bright field, and recording of images on plates or via video imaging systems including image intensifiers and digital image storage. Loss of recognition of protamine, including its 5 A substructure, followed approximately three-hit kinetics with a Do on the exponential portion of the curve of about 470 e/A2. In spite of the inevitable chemical damage at high doses, virtually all molecules in orientations that exhibited the characteristic protamine structure could still be recognized in dark field scanning transmission or fixed beam bright field at 100-200 e/A2. Recognition fell from 30 to 6% when doses were increased from 1000 to 2000 e/A2 in fixed beam dark field. Exposure rates, varied over seven orders of magnitude from 0.15 e/A2-s to 3 X 10(6) e/A2-s, had no effect at all on the recognition of structures.

Animals↗