Ion Exchange Fundamentals and New Challenges

Mass Transfer - Advancement in Process Modelling ◽

10.5772/60864 ◽

2015 ◽

Author(s):

Maria Angélica Simões Dornellas de Barros ◽

Marcelino Luiz Gimenes ◽

Melissa Gurgel Adeodato Vieira ◽

Meuris Gurgel Carlos da Silva

Keyword(s):

Ion Exchange ◽

New Challenges

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Embedding Procedure for Water Swollen Samples

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006951x ◽

1970 ◽

Vol 28 ◽

pp. 504-505

Author(s):

Ann M. Thomas ◽

Virginia Shemeley

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Ion Exchange ◽

Structural Changes ◽

Cross Linking ◽

Ion Exchange Resins ◽

Transmission Electron ◽

First Pass ◽

Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

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New challenges to image processing posed by cryo-Electron microscopy of single particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086416 ◽

1991 ◽

Vol 49 ◽

pp. 422-423

Author(s):

Joachim Frank

Keyword(s):

Electron Microscopy ◽

Phase Contrast ◽

Particle Orientation ◽

Single Particles ◽

Contrast Transfer Function ◽

Virtual Absence ◽

Cryo Electron Microscopy ◽

Spatial Frequencies ◽

New Challenges ◽

Particle Images

Compared with images of negatively stained single particle specimens, those obtained by cryo-electron microscopy have the following new features: (a) higher “signal” variability due to a higher variability of particle orientation; (b) reduced signal/noise ratio (S/N); (c) virtual absence of low-spatial-frequency information related to elastic scattering, due to the properties of the phase contrast transfer function (PCTF); and (d) reduced resolution due to the efforts of the microscopist to boost the PCTF at low spatial frequencies, in his attempt to obtain recognizable particle images.

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