Aqueous solutions of AOT as a dispersion medium for stabilization of SiO2 nanoparticles

The changes in pH and electrical conductivity of ferric tellurate, chromium tellurate and aluminium tellurate sols during their slow coagulation in the presence of KCl, K2SO4 and K3Fe(CN)6 have been studied in comparison with that of the aqueous solutions of ferric chloride, chromium chloride and aluminium chloride acting as the dispersion medium (the socalled intermicellar liquid), being of the same conductance as that of the respective sol. On adding the electrolyte, the maximum changes in conductance and pH have been observed to occur immediately indicating that the phenomena like ion-exchange, adsorption or surface neutralisation during the slow coagulation are instantaneous processes.

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A Study of Structural Organization of Water and Aqueous Solutions by Means of Optical Microscopy

10.20944/preprints201901.0044.v1 ◽

2019 ◽

Author(s):

Tatiana Yakhno ◽

Vladimir Yakhno

Keyword(s):

Ionic Strength ◽

Aqueous Solutions ◽

Dispersion Medium ◽

Structural Organization ◽

Intrinsic Property ◽

Average Diameter ◽

Dispersed Phase ◽

Liquid Part ◽

Water Salt ◽

New Phase

It is shown that structuring at the microlevel is the intrinsic property of water and aqueous solutions. At room conditions water (including "ultrapure" one) and aqueous solutions are dispersed systems in which microcrystals of NaCl, surrounded by a layer of hydrated water (average diameter - 10-15 microns), are "elementary microparticles", which form the basis of the dispersed phase. Possible ways of formation of these microparticles and their evolution in the process of evaporation of unstructured part of water - dispersion medium - are considered. It is shown, in particular, that they are present in the air as aerosol contaminants. When the ionic strength of the solution increases, the water-salt particles coagulate, forming a new phase - coacervates, remaining on the substrate after evaporation of the liquid part of the water. The aggregates of coacervate structures, formed in a liquid medium, are disordered during heating, which can cause a change in a number of physicochemical properties of water at the temperatures of 50°-60°C range that have not been correctly explained in the framework of atomic-molecular concepts.

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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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