scholarly journals Ion Exchange Fundamentals and New Challenges

Author(s):  
Maria Angélica Simões Dornellas de Barros ◽  
Marcelino Luiz Gimenes ◽  
Melissa Gurgel Adeodato Vieira ◽  
Meuris Gurgel Carlos da Silva
Keyword(s):  
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley

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.


Author(s):  
Joachim Frank

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.


2005 ◽  
Vol 38 (17) ◽  
pp. 80
Author(s):  
NELLIE BRISTOL

2012 ◽  
Author(s):  
Maggie Campbell ◽  
Katherine Lacasse ◽  
Lucas Mazur ◽  
Rashmi Nair

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