The Influence of the Ionic Medium on the Behaviour of Sodium Glycocholate and Cholate Aqueous Solutions

The composition and stability of uranyl citrate complexes in aqueous solutions of the ionic medium of 1M-(H,Na,(UO2)0.5)A3 (where H3A represents citric acid) were studied based on the potentiometric and spectrophotometric data. The best fit to the experimental data was obtained with the set of complexes UO2A-, (UO2A)22-, HUO2A, (HUO2A)2, and H2UO2A+, the former three complexes being significant in the whole concentration region.

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Ultrathin frozen sections of yeast without aldehyde prefixation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100081152 ◽

1978 ◽

Vol 36 (2) ◽

pp. 58-59

Author(s):

K. J. Böhm ◽

a. E. Unger

Keyword(s):

Aqueous Solutions ◽

Biological Material ◽

Yeast Cells ◽

Frozen Sections ◽

Good Preservation ◽

Ultrathin Frozen Sections

During the last years it was shown that also by means of cryo-ultra-microtomy a good preservation of substructural details of biological material was possible. However the specimen generally was prefixed in these cases with aldehydes.Preparing ultrathin frozen sections of chemically non-prefixed material commonly was linked up to considerable technical and manual expense and the results were not always satisfying. Furthermore, it seems to be impossible to carry out cytochemical investigations by means of treating sections of unfixed biological material with aqueous solutions.We therefore tried to overcome these difficulties by preparing yeast cells (S. cerevisiae) in the following manner:

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Imaging polymers, proteins and dna in aqueous solutions with the atomic force microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152136 ◽

1989 ◽

Vol 47 ◽

pp. 32-33

Author(s):

S.A.C. Gould ◽

B. Drake ◽

C.B. Prater ◽

A.L. Weisenhorn ◽

S.M. Lindsay ◽

...

Keyword(s):

Amino Acids ◽

Dna Sequencing ◽

Aqueous Solutions ◽

Atomic Force Microscope ◽

Piezoelectric Crystal ◽

Atomic Force ◽

Structure Of Molecules ◽

Optical Lever

The atomic force microscope (AFM) is an instrument that can be used to image many samples of interest in biology and medicine. Images of polymerized amino acids, polyalanine and polyphenylalanine demonstrate the potential of the AFM for revealing the structure of molecules. Images of the protein fibrinogen which agree with TEM images demonstrate that the AFM can provide topographical data on larger molecules. Finally, images of DNA suggest the AFM may soon provide an easier and faster technique for DNA sequencing.The AFM consists of a microfabricated SiO2 triangular shaped cantilever with a diamond tip affixed at the elbow to act as a probe. The sample is mounted on a electronically driven piezoelectric crystal. It is then placed in contact with the tip and scanned. The topography of the surface causes minute deflections in the 100 μm long cantilever which are detected using an optical lever.

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